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H12. u . a1. 12111.1. 1a a 11222121222 ‘12» II 21221 2 ‘ 2211221221‘ _. .2 2": 21111 :I Mm“ 1}} }s5 1 .21 ; 2g ,. “II“}} 1}“} W H} u. 21, MM 22 1}“ I [52117 2 .11. 2...; 21; 21211;. 1 3.11 1:; 122.2 1 ‘1 11s1‘11I121122211:1111111 22; ‘2 112 I11, I" 221112222 2211 2 21 222121222212 I 1.1 s .22 ,* . . 1..."... m I ““ “ “ '“I III“ II.“.“}I“}III1I “““I ““““ “I “ ' ““ “I“ “““I IIIIIII "111.21 III“ , :I III} IIII“I““'I“III1I III“ 111'}! “III “I“1IIII“ —.~' 11 Mil“ :1. 111“ “\III 1211 12““III“““ “““1},““““1“. “L ' M ‘ 3.. .p, , . nu--- n--..|_‘ \ .‘ a . . -' ‘.g’ THESKJ " '4 ‘0 an." , " 4.... 4 I); Pay :tw'fibbe C - w P - , 6 t, m...” wauaéy This is to certify that the thesis entitled Influence of Meloidogyne hapla on the ontogeny of Michigan crops grown in organic soil presented by Robert G. Van Arkel has been accepted towards fulfillment of the requirements for Masters degreein Entomology Major professor Date February 23, 1982 0-7639 MSU LIBRARIES 4.3—. RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. OCT 2 5 2004 'gb 04. " 5t 1-. u v‘ INFLUENCE OF MELOIDOGYNE HAPLA ON THE ONTOGENY OF MICHIGAN CROPS GROWN IN ORGANIC SOIL by Robert G. Van Arkel A THESIS Submitted to Michigm State University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE Department of Entomology I982 ABSTRACT INFLUENCE OF MELOIDOGYNE HAPLA ON THE ONTOGENY OF MICHIGAN CROPS GROWN IN ORGANIC SOIL by Robert G. Van Arkel Meloid_ogzne M (northern root-knot nematode) has a detrimental influence on the growth md development of _Qau_£_u_s CM, Solanum tuberosum, Apium graveolens, and to a lesser extent m gag. M. h_a£lg influenced the early ontogeny of Q. gafltg (especially cv Gold Pac). Shoot growth of Q. ca_rot_<_1_ was stimulated by nematode invasion between days 7 md 2|. M. M damage to Q. <_:g_g_3t_a was reduced by planting at a cooler terrperature. Tuber weight md quality of S. tuberosum was retarded by M. h_agl£. M. I'M was found to reproduce on S. tuberosum roots md tubers. Fresh weights of A. graveolens md A. 9522 exhibited no significmt differences, whereas dry weights were reduced from increasing population densities of M. Lam during the first 35 days of growth. M. M's inpact was less on transplanted than on seeded A. graveolens. The results are discussed in relation to integrated nematode management programs. DEDICATION Because of two, I became one. Because of one, We become two. Thanks for the gift of life, And our life, Mom, Dad and Sarah. ii ACKNOWLEDGMENT Words will never truly express my sincere gratitude to Dr. George W. Bird for the opportunity to achieve one of my personal goals. I appreciate his patient understanding md continual encouragement throughout the extended duration of this mmuscript preparation. I also thank Dr. Dean Haynes, Dr. Melvyn Lacy, md Dr. Alan Putnam for their assistance on my graduate committee and in this mmuscript preparation. A very special thanks goes out to Natalie md John for their friendship, technical knowledge, field assistance, encouragement and willingness to share their experiences aid time. Special thanks to my whole family and friends, who have always been there when I needed them. You will never know how much your understanding, encouragement and confidence in me was needed and used to attain this important personal goal. TABLE OF CONTENTS LIST OF TABLES ............. . ......... LIST OF FIGURES ...................... LIST OF PHOTOGRAPHIC PLATES .............. INTRODUCTION .................... LITERATURE REVIEW ................. I. 2. 2. I 2.2 Meloidqune hggla ................ Organic soil crop production ............ 2.2.I M 99931 ............... 2.2.2 Solanum tuberosum ............. 2.2.3 AM raveolens .............. 22-4 M 9322 . ............... MATERIALS AND METHODS .......... I ..... 3.I 3.2 3.3 Daucus carota .................. 3.I.I Early-season ontogeny of Q. carota in- fected with M. M ........... . . 3.I.2 Influence of‘ the date of M. hapla inocu- lation on the ontogeny of two cultivars of Q. carota ........ . . . ..... 3.I.3 Effect of M. hapla on Q. carota ontogeny under two temperature progressions ...... Solanum tuberosum ................ 3.2.I Pathogenicity of M. hapla to §_. tubero- gmrootsandtubers . . . . . . ...... Agium graveolens md AIIium capo ......... 3.3.I Early-season ontogeny of A. graveolens md _A_. c_ea infected with M. hggla ...... iv \INWM 11 14 15 19 19 19 20 24 26 26 29 29 TABLE (X'- CONTENTS, continued 3.3.2 Influence of four population densities of M. hapla on the ontogeny of A. grave- 3Iens and A. cepa ............. 4. RESULTS ....................... 4.| Daucus carota ..... . . . . ......... 4.I.I Early-season ontogeny of Q. carota in- fected with M. hgpla ............ 4.I.2 Influence of the date of M. M inocu- , lotion on the ontogeny of two cultivars of Q. carota ................ 4. I .3 Effect of M. hapla on Q. carota ontogeny under two temperature progressions ...... 4.2 Solanum tuberosum ................ 4.2.l Pathogenicity of M. hapla to S. tubero- _sgr_n roots and tubers ............ 4.3 Apium graveolens md AIIium cgga ......... 4.3.I Early-season ontogeny of A. raveolens and A. c_epg infected with M. M ...... 4.3.2 Influence of four population densities of M. la on the ontogeny of A. grave- 9'le_n_§ A. gm ............. 5. DISCUSSION ..................... 5.I Mm .................. 5.2 Solanum tuberosum ................ 5.3 Apiu_m graveolens md AM 3992 ......... 5.4 Integrated nematode management for selected muck vegetables ................. 6. LITERATURE CITED .................. 7. APPENDIX: CARROT-NEMATODE MODEL ........ LIST (1" TABLES Table Page I Influence of Meloidogyne hapla at three initial ’ population densities on the taproot quality of Daucus carota (cv Spartan Premium md Gold Pac), recorda for seven harvest dates ................. 48 2 Influences expressed, due to the inoculation day of Meloidogyne hapla, on taproot marketability and root galling index of Daucus carota (cv Spartan Premium and Gold Pac) . . . . ................. 59 3 Influence of Meloidogyne hapla did two soil temperature regimes on the taproot quality of Daucus carota (cv Gold pac), recorded for two harvest dates . . . . 76 4 Influence of Meloid ne Ia on the tuber quality and degree a root galling of Ianum tuberosum (cv Norchip), recorded for four harvest dates ......... 86 5 Influence of Meloidogyne h_apla at four population densities on the dry weight of entire plmts of Apium araveolens and AIIium 92% recorded for five harvest tes . . ...................... 89 6 Influence of Meloidggyne Law at four population densities on the number of root galls on Apium graveolens md AIIium 93mg, recorded for five harvest dates ........................ 90 7 Influence of Meloidggzne hapla at four population densities on the soil population of second-stage larvae related to Apium graveolens and Allium cepa, recorded for five harvest dates ............. 91 8 Influence of Meloidogyne hapla at four population densities on the fresh nght measurements of ium graveolens and AIIium cepa, recorded after IO days of growth ...................... 92 9 Influence of Meloidogyne hapla at four population densities on the dry weight measurements of ium raveolens and Allium cepa, recorded after IO ys of growth ...................... 93 vi LIST (1" TABLES, continued Table ' Page IO Influence of Meloid ne hapla at four population densities on the served nematode population densities. in %ium graveolens and Allium cepa, recorded after days of growth - ............ 95 II Influence of Meloidogyne hapla at four population densities on quality characteristics of Apium graveolens and AIIium cepa, recorded after I0 do of growth ....................... 96 I2 Data summary of various characteristics which can be used to determine whether Daucus carota, Solanum tuberosum, Apium graveolens, or AIIium cepa fit into a crop rotation program designed to reduce Meloidggzne M populations . . . ........... 104 A-I Fresh weight of carrots md yield predicti%n at various initial nematode levels for a plmting at 50 F ....... I33 A-Z Fresh weight of carrots md yield prediction at various initial nematode levels for a plmting at 60° F ....... 135 A-3 Fresh weight of carrots md yield prediction at various initial nematode levels for a planting at 80° F ....... 136 A-4 Fresh weight of carrots md yield predicti%n at various initial nematode levels for a planting at 70 F ....... 137 vii PLEASE NOTE: Page number viii is missing in number only. Filmed as received. UNIVERSITY MICROFILMS INTERNATIONAL LIST (I: FIGURES Figure Influence of Meloid_ogzne Ia at three initial population densIties on t t weight of Daucus carota (cv Gold Pac) ................. . Influence of Meloi% Ia at three initial population densIties on t t weight of Daucus carota (cv Spatan Premium) .............. Influence of Meloigggzne m at three initial population densities on t shoot surface area of Dweuscarota(choIdPoc)............... Influence of Meloid_ogzne ha la at three initial population densIties on t t surface area of Daucuscarota(cv Spatan Premium) . . . . . . . . . . Influence of Meloi ne Ia at three initial population densities on t t height of Daucus carota (cv Gold Pac) ................. Influence of 4.42% h_apl_a at three initial population densities on the shoot height of Daucus carota (cv Spartm Premium) ........... . . . . Influence of Emmi} M at three initial population densities on t root weight of Daucus carota(choldPac) . . . . . . . .......... Influence of Meloid_ogzne hgla at three initial population densities on the root weight of Daucus carota (cv Spartan Premium) .............. Influence of Meloi ne PEPE at three initial population densities on t root surface area of Daucus carota (cv Gold Pac) .............. Influence of Meloid_o_gyne hapla at three initial population densities on the root surface area of Daucus carota (cv Spatm Premium) .......... Influence of Meloid_ogzne QgpLa at three initial population densities on the taproot length of Daucus carota (cv Gold Pac) ................. ix 36 37 38 39 40 41 42 43 44 46 LIST (I: F IGURES, continued Figure . Page I2 Influence of Meloid_ogyne hapla at three initial population densities on the tmroot length of Daucu___s_ c___arota (cv Spartan Premium) ............... 47 l3 Influence of Meloidggyne hapla at three initial population densities on galls per taproot on Dau—cus c__arota (cv Gold Pac) .................. 49 I4 Influence of Meloidogyne hapla at three initial population densities on galls per taproot on Daucu____s c_a_r_ota (cv Spartan Premium) ....... . . . . . . . . 50 I5 Influence of Meloidgyne hapla on shoot system height of Daucus carota W Spartm Premium) due to inoculation date .................... 51 I6 Influence of Meloid ne Ia on shoot system height of Daucus carota Icv %5Id ac due to inoculation date . . . 52 I7 Influence of Meloidogyne Sgpjg on shoot weight of Daucus c_<_I__rota (cv Spartan remium) and Gold Pac) 35¢ to inoculation date ...... . . . ........ 54 I8 Influence of Meloid ne ha la on shoot surface area of Daucus carota Icv Spartan emium md Gold Pac) due to inoculation date ................. 55 I9 Influence of Meloidogyne hapla on taproot length of Daucus carota (cv Spartan Premium and Gold Pac) due to Inoculation date ..... . ............. 56 20 Influence of Meloidogyne la on taproot weight of Da__ucus carota (cv Spartan remium and Gold Pac) due to inoculation date ................... 57 2I Influence of Meloi ne la on lateral root weight of Daucus carota Icv gartm emium and Gold Pac) dueto inoculation date ..... . ....... . . . . 58 22 Influence of Meloi ne hapla on galls per lateral root on Daucus carota cv Spartan Premium and Gold Pac) due to inoculation date . . . . . . . . ....... 60 23 Influence of Meloid on soil population levels from Daucus carota Icv ISpartm Premium and Gold Pac) due to inoculation date ............. 62 LIST (I: FIGURES, continued Figure . Page 24 Influence of Meloid_ogyne ha la on nematodes per lateral root on Daucus carota Icv Spartm Premium md Gold Pac) due to inoculation date ........... 63 25 Influence of Meloidggyne ha Ia on nematodes per gram of root on Daucus carota cv Spartm Premium and Gold Pac) due to inoculation date ............. 54 26 Influence of Meloid ne la on eggs per gram of root on Daucus carota Icv artm Premium and Gold Pac) due to inoculation date ............... 55 27 Influence of Meloidggyne h_aLla_ and two soil temperature regimes on the shoot weight of Daucus carota (cv Gold Pac) .................. 59 28 Influence of Meloi ne ha Ia md two soil temperature regImes on t t height of Daucus carota (cv Gold Pac) .................. 70 29 Influence of Meloidggyne hapla did two soil temperature regimes on the shoot system surface area of Daucus carota (cv Gold Pac) ......... ‘ ..... 71 30 Influence of Meloid_ogyne hapla did two soil temperature regimes on the root system weight of Daucus carota (cv Gold Pac) ............... 72 3| Influence of Meloid_ogyne h_apl£ did two soil terrperature regimes on the taproot length of Daucus carota (cv Gold Pac) .................. 73 32 Influence of Meloidggyne @Ia and two soil temperature regimes on the root system surface area ofDaucuscarota(choldPac) ...... . . . . 74 33 Influence of Meloidggyne ‘hapla and two soil temperature regimes on the number of galls on the taproot of Daucus carota (cv Gold Pac) ---------- 77 34 Influence of Meloidgqyne hapla and two soil temperature regimes on the number of galls per lateral root of Daucus carota (cv Gold Pac) ........ 78 35 Influence of Meloidggyne hapla and two soil terrpergture regimes on the number of M. h Ia per I00 cm of soil on Daucus carota (cv Gold—Pac ....... 79 xi LIST (I: F IGLRES, continued Figure 36 37 38 39 A-Z A-3 A-4 Influence of Meloidflyne Lap? and two soil temperature regimes on NE nu er of M. hgpla per root system of Daucus carota (cv Gold PacT ....... Influence of Meloidogyne hapla on the number of tubers per plant of Solanum tuberosum (cv Norchip) . . . . Influence of Meloid ne ha la on the tuber fresh weight of Solanum t erosum cv Norchip) ........ Influence of MGIOMM hafila on the number of second-stage juveniles per cm3 of soil md per gram of root, md eggs per gram of root on Solanum tuberosum (cv Norchip) . . . ......... . . . . . Life cycle of Meloidggzne hapla ............ Effect of temperature on development of 2nd stage larvae to 3rd stage larvae of Meloidogyne Lam ..... Rate of oviposition of Meloid_ogyne _hgglg ........ Effect of terrperature on egg hatching of Meloidggz ne ELI ........................ xii Page 84 85 87 118 124 125 127 LIST (F PHOTOGRAPHIC PLATES Plate Page I Symptoms caused by the influence of Meloidgyne M on the ontogeny of Daucus carota under field conditions ....................... 10 2 Influence of Meloid_ogyne hapla and two soil temperature regimes on the ontogeny of Daucu__s c__arota (cv Gold Pac) .................. 67 3 Influence of Meloid ne hapla on the ontogeny of Solanum t____uberosum cv Norchip) ............. 82 xiii I. INTRODUCTION Michigan vegetable production was four percent greater in I976 thm in I975, producing fresh and processed vegetables valued at nearly $85 million. Increased production was attributed to favorable weather conditions, and to increases in acreage md yields (56). Production has continued to increase since I976 to a production level of SI l4.3 million in I979 (57). Michigan was fourth nationally in acreage of fresh market vegetables harvested in I976. Production value was estimated at $70 million for the I4 major vegetable crops, with carrots (M car—ota L.) accounting for l7.5 percent of this production (56). The combined value of summer and fall carrot production in I976 was $I2.2 million, 30.4 percent cbove the I975 value (56, 94). The value of Q. cLotg production in I979 was $l3.4 million (57). Michigm ranked fifth in I979 among the states in the nation in fresh market md processing _D_. c_grflg production (56, 57, 94). This was down from third place in I976, and second place in I975. Michigm‘s production accounts for 8.2 percent of the total United States mnual production of Q. (115912 (57). In Michigan, potatoes (Solanum tuberosum) are usually considered m agronomic crop. The combined value of summer and fall S. tuberosum production in I976 was $35.4 million, 2|.2 percent below the I975 value. This reduction resulted from 0 I9 percent increase in the I976 crop over I975 production which forced the price per cwt. to drop from $5.56 to $3.68 (56). Producers earned $67 million from the sale of the I978 crop (57). Michigan ranks eleventh in the nation in S. tuberosum production, supplying 2.7 percent of the total annual United States crop (56, 57). In I970 the estimated annual crop loss attributed to damage caused by plmt-parasitic nematodes was 20 percent (8|). The northern root-knot nematode (Meloidggzne M Chitwood, I949) is widely distributed throughout the world, md of economic importance where it occurs (23, 72). M. Mg is the major nematode pathogen in Q. (£919 production in the Uiited States did other parts of the world (I3, I5, 34, 82, 94). Although M. M is not the major nematode pathogen in S. tuberosum production, it causes significant economic losses when present at high population levels (20, 32, 33, 42, 43, 48, 54, 6|, l06). Both Q. c_<_1r_gt9_ aid S. tuberosum are good hosts for M. h_aLIa_ reproduction. In Michigm, Q. m is grown in orgmic soils (muck) in rotation with celery (AM graveolens , onions (AIM gm), md S. tuberosum. Major S. tuberosum production in Michigm is on mineral soils, but muck soils are particularly well adapted to S. tuberosum production if well drained, fertilized adequately, aid frost free during the growing season (l8). When grown on muck, S. tuberosum is often rotated with Q. $919: A. ggaveolens or A. c_efl. Because of the interrelated nature of these crops md their importance to Michigan‘s economic stability in crop production, they have become the center of this study. The objective of this research was to evaluate the influence of M. Ia on the initial growth md development of Q. M, S. tuberosum, A. graveolens did A. ggpg. Nematode population dynamics, symptomatology, md nematode control were also studied in relation to the research objective. Special attention was given to Q. c_aro_tg. The research was designed to provide information necessary for the design of predictive pest management models for the northern root-knot nematode in muck soil crop production systems, and to improve the understanding of the host-parasite relationships. 2. LITERATURE REVIEW . 2.I Meloidogyne hapla Meloidogyne was described by Goeldi in I887 (47). The first reported observation of this nematode in the United States was made by May in I888 (55). Prior to I949, both root-knot md cyst nematodes were classified as members of genus Anguillulina by Goodey md reassigned six times by others before being placed in the genus Meloidogyne by Chitwood (2|, 30). Because of the discrepancies prior to I949, interpretation of early studies is difficult. M. hapla is a member of the following taxa: Order: Tylenchido Superfamily: Heteroderoidea Family: Heteroderidae Subfamily: Meloidogyninae (47). Trimtaphyllou reported the existence of two races of M. h_a_pl_a, Type A md Type B. They differ in chromosome number md method of reproduction (90, 9|). Others reported the existence of physiological races based on an ability to feed and reproduce on specific hosts (7 I). The detailed morphological characteristics of M. M were compiled by Whitehead in I968 (23). The life cycle of M. _thlq consists of an egg, four larval or juvenile stages, female and male. Sexual dimorphism is present. The adult female is didelphic and spherical, swollen or pear-shape in appearance. Males are monorchic aid vermiform in shape (6, 23, 47, 92). The duration of the life cycle is dependent UPC" temperature, 02, C02, food source, soil moisture, and other factors (35, I08, l09, IIO). Twenty-five days is the minimum time reported for completion of the life cycle (larva to larva) of Meloidogyne spp. .in tomato roots at 27.0 C (92). The process took 87 days at l6.5 C (92). The second-stage vermiform juvenile is the infective stage. After hatching, the second-stage juvenile migrates through the soil to a root and penetrates immediately basipetal to the subapical meristematic region of the root of a potential host (23, 47). Both primary and secondary host symptoms are caused by M. “.2219 infection. The primary symptom consists of hyperplastic galling. Secondary symptoms consist of reduced yields, wilting, stunting of plant growth, yellowing of plmt foliage, early senescence, delayed maturity, and poor bloom (I3, 70, 80). Internal symptoms include production of syncytia or multinucleate transfer cells, known as giant cells. They are initiated by Second-stage juveniles and result in both hypertrophy and hyperplasia (8, 27, 40, 47, 99). Giant cells are the source of nutrition for developing M. M. Although root invasion occurs, individuals of M. _hgprill not mature without the development of giant cells (23, 47, 88). Host penetration by second-stage juveniles in M. h_apM is quite variable. A I933 study by Tyler (92) showed that root penetration and gall formation in cultures required 96 hours or more at I5.0 C, with it decreasing to 2| hours at 35.0 C. Bird and Wallace (9) found that only 2.9 percent of 60,000 nematodes entered tomato seedling roots after 48 hours when temperature was not controlled (I4-45 C). Many larva may enter the root at a single infection court (80). The time for root penetration of Q. ggr_otg_ and A. c_efl was reported as 24 hours (I3, 80). Nematode life cycles are dependent on environmental conditions, including the host. Several workers reported the influence of temperature on the duration of development did the life cycle of M. h_qp£ (9, I3, 25, 26, 92, 96, 97, l07, l09, I ID). The shortest reported life cycle was I9 days on tomato (92). The longest was on A. 92% under Michigm field conditions at 72 days (I3). Under Michigm greenhouse conditions the following durations were recorded; 45 days for Q. 9291.0: 72 days for A. c_efl, aid 56 days for A. graveolens (I3). The developmental threshold for growth and development was reported by Tyler (92) at 9-I0 C for Meloidggyne spp., and Vrain 91 a_l. (97, 98) reported a minimal developmental temperature of 8.8 C for M. h_apl_g larvae, md 6.74 C for M. M eggs. M. M has a high reproductive potential that depends on the host plcnt md environmental conditions (9, I09). One female was observed to deposit 2,882 eggs "without becoming exhausted" (92). Hendricks _el a_l. reported 01 average of 467 eggs per mass, with a range of 25-l,337 (36). Optimum temperature for egg laying is between 23-24 C, with no egg deposition above 3|.5 C (92). Juveniles hatch or emerge from the egg masses when moisture, temperature, 02 md C02 are favorable (5, l09). In some cases, hatching is a response to root exudates (95). Optimum temperature for the hatching of M. Lam eggs is 25 C (9). Terrperature is m important factor in the worldwide distribution of Meloid_ggzne spp. M. M is extremely tolerant of cold temperatures but has a lower tolerance to high temperatures than most Meloidgyne spp. (5, 9, 24, 74, 96, 97). Daulton and Nusbaum (24) found that M. h_aLIg eggs were more tolerant to 2 C md less tolerant to 33 C than those of M. iavanica. The daility of M. M eggs to overwinter was demonstrated by their viability after 250 days exposure to temperatures from 3| C to 0 C (24). Sayer (74) reported M. h_opl£ survived freezing temperatures better thm M. incgmita. Formation of internal ice, however, was lethal to both species. He also reported that at Harrow, Ontario, Cmada, a field population was reduced by 75 percent during the winter months (73). In cool, temperate climates like Michigan, the overwintering stage is the egg (I3, 73). Second-stage juveniles overwinter in many geographical locations (I6, 23). Wieser (I04) reported that the apical 2 mm of excised tomato roots were repellent to nematodes, whereas the next basipetal 6 mm were attractive. Bird (7) found that the attraction of Meloidggzne spp. to plant roots was probably dependent on factors such as root exudates. The optimum terrperature for mobility of Meloidgyne spp. is 20 C and the optimum temperature for invasion is I5-20 C (9). In muck soil, night and day temperatures of 2|.I and 26.7 C were optimum for mobility and invasion (l09). The optimum soil moistures were 80 cm suction for mobility and I00 cm suction for invasion (l09). Spread of M. M under field conditions is a function of the rate of population increase on a specific hostplant. Migration of M. h__ang was slower when associated with Q. 99.93! ad more rapid on lettuce (Lactuco M), where it spread at least 50 cm per year from its inoculation point (85). An integrated qaproach to mmagement of M. M problems is important in crop production. Programs should incorporate exclusion, population reduction, use of resistant varieties md plant protection practices. The most successful control programs are those that integrate several methods to keep nematode populations below the economic threshold (I I, 28, 52). Some chemicals previously used for nematode control are no longer available, and others may be withdrawn from the market in the near future. Chemical availability depends on the crop and the way the chemical is applied. Current registered chemicals for these muck-grown crops are dibromomethane (Methyl, bromide), nitrochloroform (Chloropicrin), I,3-dichloropropene (I,3-D), I,3-D plus chloropicrin, I,3-D plus methylisothiocymate (MIC), ethylene dibromide (EDB), EDB plus chloropicrin, methyl ‘N,N-diethyI-N,methyl carbamoyl-oxy.-I-thiooxamimidate (Oxamyl), and 2-methyl-2-(methylthio) propionaldehyde 0-(methylcarbamozl) oxime (Aldicarb). No known chemical pesticide is suitable for eradication of a nematode population under field conditions. Carbofuran has been shown to give 75 to 90 per cent control of nematodes for I0 to I2 weeks but does not have a label for use on Q. gum (37). Potentials for biological control include nematode trapping fungi, parasitic bacteria, protozoans, aid predaceous nematodes (SI, 53, 62, 75, 76, 86, 87, 88). 2.2 Orgmic soil Crop Production 2.2.I Daucus carota A I97I survey of 500 Michigcn consumers showed than 60 percent were frequent purchasers of carrots (at least twice per month) (60). Ninety-four percent preferred fresh carrots. Cmned Cl‘ld frozen Q. ggrgtg were purchased in lower quantities. The common characteristics used by a consumer in the purchase of fresh carrots fall into eight categories: I) size md shape, 2) color, 3) firmness md appearance, 4) no decay or spoilage in the package, 5) clean, 6) smooth with no hairs, 7) no green ends, did 8) miscellaneous including no broken carrots, tops on, tops off, etc. (60). Q. m usage ranged from snacks, relish trays, salads, cooked in stews or casseroles, canning or freezing, md eating whole out-of-hand (60). Q. M are rich in Vitamin A, and contain appreciable qumtities of thiamine, riboflavin aid sugar (89). Q. <_:_ar_ot_g, a cool-season vegetable, is a biennial of the Umbelliferae (parsley family). Q. m is native to Europe, Asia, and Northern Africa, and possibly North and South America (89), and is grown throughout the world with major production and use in Europe. When planted from seed, the first year produces a thickened storage taproot md a whorl of leaves. Second-year crowns produce a flower stalk which grows to the height of 2 to 3 feet (89). The majority of Michigan Q. m are produced in muck soils, with major areas of production located in Newaygo, Muskegon, Ottawa, Lapeer and Allegan counties. Muck-grown Q. c_arglg generally have smoother roots than Q. _ca_r_glg grown on mineral soil (l02). Summer Q. 9223'. production in Michigan yields 230-260 cwt per acre, md fall production of Q. gg_r_9_tg yields 250-290 cwt per acre (58). The general range for Q. m seed germination is 5.2-29.5 C. The minimum temperature for Q. Ego—ta seed germination is 4.44 C (49). Direct field seeding of Q. gLota requires 2-I/2 to 3 pounds of high quality seed per acre (49). Field spacing varies depending on the operation md equipment. Spacing between rows ranges from I6-36 inches and l-3 inches between the plants in the row (49). M. [Law is a highly significant pathogen of Q. ggrgtg in Michigm (Plate I). An excellent review of M. M and its interactions with Q. c_a_r_gtg was written by Slinger (77, 79). Symptoms of M. M infection include galls, taproot distortion, yield losses, and plant mortality (4, l4, I5, I05). Significant differences of growth in the shoot system of nematode infected plants could be seen as early as l2 days after seeding (78, 79). Q. 20.5% roots infested with M. M showed a 50 percent reduction in the activity of phenylalanine ammonia- lyase and ribonuclease, a doubling of RNA synthesis, about 70 percent higher protein content, and a decrease in indolylacetic acid oxidase activity (22, 44, 50). Plate I. Symptoms caused by the influence of Meloidogyne hapla on the ontogeny of Daucus carota under field conditions. Starting at the top right, follow the arrows: I. common expression of hairy root; 2. close-up showing enlarged lenticels, galling md hairy-root symptoms; 3. large root gall causing branching of feeder root; 4. degree of symptom variation caused by M. hapla under field conditions. 10 NORTHERN ROOT-KNOT HAI RY-ROOT 11 2.2.2 Solanum tuberosum The S. tuberosum is m important food crop, especially in temperate zones. S. tuberosum was cultivated by early pioneers who settled in Michigan, md in I780, 2,885 bushels of S. tuberosum were planted in the Detroit area (59)., In terms of total production of energy for human consumption, S. tuberosum ranks fifth behind the cereal and grain crops of wheat, maize, rice md barley (93). The composition of an average S. tuberosum tuber is about 80 percent water, 2 percent protein, and I8 percent starch (89). As a food source, it is one of the chemest methods of acquiring carbohydrates md furnishes appreciable amounts of Vitamin Bl md C as well as some minerals (89, 93). Selection of the proper cultivar is essential for production of quality commercial or home garden potatoes. Cultivars should be adapted to the soil and cultural conditions under which they will be produced and marketed. S. tuberosum is used for fresh market, chip processing, baking, french fries, dry md frozen processing, salads, certified seed, alcohol and stockfeed (I7, 59, 93). United States per capita consumption of S. tuberosum was I l5.0 pounds in I976 (56). Approximately 50% of the total Europem S. tuberosum production is used as stockfeed, and about 40% is grown specially for that purpose. In the USA, 80% of the total production is used for humm consumption. The other 20% is seed, waste, loss, etc. The waste and loss in the USA are extremely low in comparison with that of Europe (93). S. tuberosum is a cool-season vegetable md a member of the Solanaceae or Nightshade family (49, 89). Peru is thought to be the place of origin of S. tuberosum; cultivated by the Incas high in the Andes (I9, 89). S. tuberosum cultivars include a wide range of plant characteristics with the vines ranging 12 from prostrate to erect types bearing compound leaves with opposite leaflets. Flowering may be sparse or abundant with the cultivar flower color ranging from pure white to deep purple. The true seed fruit is spherical, l/2 to | inch in diameter, and not used for propagation except in the development of new varieties (89). The stolons are slender, underground lateral stems produced from buds an the underground portion of the stem. S. tuberosum tubers are modified stem tissue originating as a stolon from an axillary bud of the underground stem (3). The most desirable Michigan soils for high yielding quality S. tuberosum are smdy, gravelly, (I'ld shale looms, or muck soils. Sites should be well drained, aerated, and supplied with orgcnic matter md available plant food. Peat md muck soils are particularly adapted to S. tuberosum production if well drained, adequately fertilized md frost free throughout the growing season (I8, 89). Montcalm County is Michigan's leading county in S. tuberosum preduction. Montcalm md Bay counties account for about one-third of the state's acreage md production. Other counties with major S. tuberosum production are Monroe, Presque Isle, Dickinson, Iron, Allegm md Van Buren (59). Tubers produced on muck soils generally have a more desirable shape and brighter color than those grown on mineral soils. Michigm is the eleventh state in production of S. tuberosum with a yield of 48|,l00 tons for I976. The summer crop yields I70 cwt per acre with 7,900 acres in production. Fall S. tuberosum yield is 245 cwt per acre with 35,000 acres harvested (56). S. tuberosum grows best where the temperature does not exceed 2|.II C. The ideal temperature for photosynthesis is 20.0 C, md the formation of tubers at |5.56 to l8.3 C (I8). Cool night temperatures are more essential than cool 13 day temperatures for tubers to accumulate carbohydrates. The length of day is irrportmt in the formation of tubers. Long days increase the vegetative top growth whereas short days induce tuber set md hasten plant maturity. Highest yields are produced where relatively long days occur early in the growing season followed by short days for tuberization (I8, 89). S. tuberosum planting in Michigm is usually done from April 25 to May 25. Plant spacings vary depending upon the type of planting equipment. Spacing between rows ranges from 30 to 42 inches and 7 to l0 inches between seed pieces in the row. The number of pounds of seed potatoes needed to plant 01 acre is dependent upon spacing md variety (l8, 49, 89). M. M is a pathogen of S. tuberosum throughout the world (20, 32, 33, 6|). Much of the literature is of little value because it is not species specific. Successive cropping of S. tuberosum without control results in a gradual increase in root galling did a decrease in yield of large tubers of more than I20 9 each (3|, 42, |03). Commercial losses to S. tuberosum cm reach 46% when the initial soil population is at I8,000 larvae per kg of soil. Marketable yields of S. tuberosum were severely reduced at initial populations as low as 666 nematodes/kg of soil (66). There has been considercble searching for resistmt varieties of S. tuberosum to M. h_a‘p_l_q md M. incggnita (I2, 38, 39, 45). Of I,473 clones of Solanum tuberosum spp. mdigena tested by Brodie and Plaisted (I2), fifteen exhibited resistance to M. M: M. 'ncggnita, M. arenaria md M. iavcnica. By crossing five of the clones showing resistance to two or more species of Meloigggyne, three families were found that contained progeny resistant to M. Qgglg (I2). Hoyman (38, 39) also noted resistance of S. microdentum md S. tuberosum spp. andigena to M. h_aglg. These varieties have 14 extensive galI-free root systems when grown in soil infested with M. M. M. _thlg larvae appear to enter tubers through the lenticels (32, l06). Common scab md bacterial pathogens of S. tuberosum enter the tuber through developing lenticels. Proliferation of the lenticels on mature tubers increased the susceptibility to pathogens (I). Parris (67) reported that higher soil moisture causes swelling of the lenticels md root-knot larvae penetrate through the tuber at these points. M. M larvae have been found near the cambium, below swollen lenticels and near the center of the S. tuberosum tuber (32). Symptoms of M. @913 infection include root galling, galled tubers, internal infestation of the tubers, blemished tubers by parenchymatous tissue growth, decreased top growth, md decreased yields both in total weight and numbers of No. I grade tubers (32, 38, 39, 42, 54, 66). Nematode control in S. tuberosum production is achieved through the use of chemicals. Fall fumigation gives good control but the present trend seems to be the use of at-plant systemic insecticide- nematicides (3|, IOI). Aldicarb md carbofuran have consistently improved tuber quality in experiments (68, |00). 2.2.3 Ap_ium graveolens The category of "Salad Crops" includes celery, lettuce, endive, chicory, parsley, chervil, cress and water cress. A. graveolens ranks second in importance among salad crops in value md popularity. It is exceeded only by lettuce (89). A. graveolens was once considered a luxury but is now common and available year round (89). Most A. graveolens is consumed raw. Other uses include canning, juice, soup, stew, salad, and as a cooked vegetable (89). A. graveolens is a biennial plant grown as an annual crop. It is a cool- 15 season vegetable belonging to the Umbelliferae, or, parsley family (34). A. graveolens thrives best where the weather is relatively cool with moderate rains and has been found growing wild throughout the world. Wild A. graveolens was probably used for medicinal purposes long before its cultivation as a food plant in France in I623 (89). A. gloveolens can flower as an mnual when small plants are subjected to temperatures of 4.44 to |0.0 C for several days, causing premature seeding (bolting). The flowers are small, white, md borne in conpound umbels among the leaves of the flower stalk, which grows 2 to 3 feet in height (89). The best soil for A. graveolens production is a fertile muck; however, it can be grown on fertile medium-textured mineral soils with irrigation (63). The major counties in Michigm with muck soil in A. graveolens production are Ottawa, Muskegon, Kent and Allegan. Michigan's summer A. graveolens production yields 445 cwt per acre with |,900 acres being harvested in I977 (58). Fall production of A. graveolens yields 430 to 450 cwt per acre with only 500 acres being harvested (58). The,optimum temperature range for A. raveolens seed germination is |5.56 -2l.l I C. The minimum temperature for A. graveolens seed germination is 4.44 C (49). Eight to fourteen weeks is required to raise transplants from seeds in open beds (49). About 8 oz of A. graveolens seed will produce enough transplants to set one acre. A. graveolens is one of the few vegetable seeds needing a soil-moisture content close to the field capacity for seed germination to occur (49). Transplanting in Michigm begins gg April I5 and continues through July I5. Michigan A. graveolens is harvested 85 to I30 days after trmsplanting. The rows are spaced 24 to 30 inches apart md a spacing of 4 to 6 inches between the plants in the rows (34). There is little literature on M. hgpla and its interactions with A. 16 graveolens. From personal field observations md the work of Brady (I3), A. graveolens is an excellent host for M. Qgglg reproduction. In Michigan, the plant-parasitic nematodes most frequently associated with A. graveolens are Paratylenchus hamatus, M. h_aglg, and Pratylenchus Enetrans. A I976 nematicide study in Michigm showed A. graveolens yields were higher where m at-planting nematicide was used compared with non-treated checks (65). M. h_ap_lg_ cm serve as a predisposition agent for numerous fungi and bacteria. This has created a concern in A. graveolens production (23, 88). Starr md Mai (83, 84) reported shoot dry weight of M. mpg-infected plants was 50% of nematode free controls 4 weeks after inoculation, with fungi and bacteria being isolated from necrotic galls. Nematode free A. graveolens transplants may produce 25% to I00% larger stalks thm root-knot infected trmsplants, even when transplanted into root-knot infected fields (34). Symptoms of M. Lapjg infection on A. graveolens include galls on the root system, wilted and stunted plants, reduced yields md root necrosis (83, 84). Nematode control in Michigan A. graveolens production is achieved through crop rotation md the use of nematicides. In Florida, a combination of summer flooding md soil fumigation is used for control (34). 2.2.4 Allium cepa The category of "Bulb Crops" includes onion, leek, garlic, shallot md chive. A. m is the most important bulb crop, and one of the most important vegetable crops (89). A. (339 is grown for consumption in the green state md as mature bulbs. A. 93m is commonly used in soup, stew, salad, cooking with meats, relish, md deep-fried onion rings. 17 A. c_em is a biennial plant grown as a mnual.crop. It is a cool-season vegetable belonging to the Amaryllidaceae, or Amaryllis family (49). A. c_eg is probably a native of Asia, perhaps from Palestine to India (89). It has been cultivated as a food for many years, and the Bible mentions it as a food for the Israelites. It is recorded as being cultivated in America as early as I629 (89). At relatively low terrperatures (I0.0 to |5.56 C) under short days (9 to I2 hours) A. c_eg plmts will seed readily. Under high temperatures (2|.II to 26.67 C), however, no seedstalks form under either short or long (l5 hour) days (89). A. c_em thrives on a wide range of soil conditions when provided with adequate moisture and fertility (64). Muck soils are ideal for A. m production. The major production areas in Michigm are Newaygo, Ottawa, Allegm, Jackson, and Calhoun counties. Each A. (m cultivar has a specific day-length requirement for bulb initiation. Varieties with a day-length of I3 to I5 hours for bulb initiation are used in Michigan. Dry onion production in Michigm is between I06,500 md l08,300 tons. The average yield per acre is 300 cwt with 7, l00 acres of A. Egg harvested annually (58). The general temperature range for A. c_egqseed germination is l0.0 to 35.0 C. The minimum temperature for A. c_eg seed germination is |.66 C (49). A. c_em requires moderately cool temperatures during the early stages of growth to permit extensive foliage and root development before bulbing starts. Day temperatures of |5.56 to l8.3 C and night temperatures of l2.74 to |5.56 C are good for early growth. High temperatures during the early growth period cause premature bulbing. During bulbing, harvesting md curing, relatively high temperatures md low humidity are needed (64). Direct field seeding of A. c_efl uses 3-4 pounds of high quality seed per acre (49). A. 9529 will reach market 18 maturity from 85 to l20 days after seeding. Row spacing in Michigm is often I6 inches with 8 to I2 plants per foot of row. The area desired per plant is about 25 square inches. Precision-seeding is needed for production of jumbo onions, where plants must be no closer than 2 inches in the row (49, 64). M. M does not (ppear to cause significant economic losses in A. 22% production in Michigan. Brody (I3) found A. c_egg to be effective in decreasing field populations of M. h_ag|g to levels where damage to subsequent Q. ggro_tg crops was decreased. Though A. 21*! cm reduce field populations of M. h_aglg, this nematode reproduces on A. gm (I3, 80). M. nglg is associated with A. m throughout the world (2, I3, 48, 66). lzatullaeva (43) reported that A. cm were resistant to infection with 500 larvae per I00 cm3 of soil. Olthof md Potter (66) report a commercial loss of 64% when A. Egg were grown in soil infested with l8,000 nematodes per kg. A pre-plant population density of 2,000 M. M per kg of soil was enough to cause greater than 5% loss of the marketable yield. Symptoms of M. [Laplg infection on A. 93m include reduction in the number of No. I onion bulbs, reduced yields, galls on the root system and reduced top weight (66). 3. MATERIALS AN) METHODS 3.l Daucus carota 3.I.l Early-season ontogeny of Q. c_a£0_t_q (cv Spartan Premium md Gold Pak) infected with M. h_apl_a_ hitial Procecbre (Dd Growth Conditions—Muck soil (coarse aggregate of organic material) already infested with viable M. M was obtained from the Michigm State University (MSU) Nematology Greenhouse. The soil came from pots in which M. gig-infested Q. M were growing. Two hundred sixteen clay pots (7.62 cm diameter) did one hundred forty-four clay pots (20.32 cm diameter) were washed md sterilized (3h at I2l C) prior to use. Two container sizes were used because the seeds were planted md inoculated in the 7.62 cm diameter pots then trmsplanted to the 20.32 cm diameter pots after I4 days of growth. Enough infested muck soil to fill all 2l6 of the smaller containers was mechmically mixed to distribute Q. £95912 roots, eggs, and second-stage juveniles everin throughout the entire soil mass. Then rmdom soil samples of I00 cm3 were taken and washed by the centrifuge flotation tecl'nique (46) to determine the initial soil population density of M. M- An average of the soil samples showed the second-stage juvenile population to be approximately 240/ I00 cm3 of soil. One-third of the muck was steamed (4 h at 88 C) md used to fill one-third of the smaller pots. One-third of the pots were filled with a soil mix containing 3 parts steamed muck did I part of the infested muck, while the final third of the pots were filled with infested muck only. This pot-filling scheme allowed an experiment where three initial population densities of M. hapla (0, 60, 19 20 240 second-stage juveniles/IOO cm3) were examined. All 2l6 of the smaller 3 of the appropriate soil mix. One hole was containers were filled with 500 cm made l.27 cm deep in the soil in each of the 2I6 pots for planting. Two seeds of Q. gm (cv Spartan Premium) were placed in the holes in each of I08 containers. Two seeds of Q. 9M (cv Gold Pak) were then placed in the holes in each of the remaining l08 containers. Each M. M initial population density for each cultivar was replicated 36 times. The plants were maintained in the MSU Nematology Greenhouse (November 23, I976, to Jmuary 4, I977) under I6 hours of light and watered daily. Monitored greenhouse temperatures showed 01 average accumulation of l5.9 degree-days per day at a base temperature of 45 C. No fertilizer or pest control chemicals were cpplied prior to planting or during the 42-day experiment. Plants were thinned daily to one per pot as the second plants emerged. Nematode loss due to thinning was assumed to be negligible. Six replicate plants from each of the three initial nematode density treatments of each cultivar were randomly selected for harvest every 7 days. After the second harvest was completed, the remaining Q. m plants were transplanted into the I44 larger pots filled with steam-sterilized (4 h at 88 C) muck soil. The Q. £912 seedlings were gently removed from the original containers and rinsed with water before transplanting. Transplanting into sterilized muck allowed a way to confine inoculation to 0 I4 day period. l'iorvesting md Evaluation Procedrres—The soil and roots of the plants harvested every seven days were removed from the pots intact, and placed on pqser for separating. Each germinating seedling, or plant root system, was removed from the soil using forceps, washed in a container of cool tap water md 21 placed in a petri dish. Soil (I00 cm3) was randomly collected and used for evaluation of M. [12919 population densities. Each plant was evaluated for shoot height, shoot surface area, fresh weight, taproot length, number of galls on the taproot, number of galls on lateral roots, taproot quality md number of nematodes observed in the root system. Shoot height was measured before harvesting the plants. The surface area of each plant was measured on a Li-Cor Model Li—3000 Portable area meter. Fresh weight of the plants (shoot and root intact for first 3 harvests) were obtained by direct weighing on a four place Mettler balance. Taproot length was measured directly after washing. Root systems were evaluated for galling by floating roots in a shallow tray of water. Taproot quality was determined through m index which ranged from I to 3, with l representing marketable, 2 representing processing quality md 3 was non-marketable. Root systems were stained to observe nematodes. The Baermann Pan technique was uSed for soil analysis. All M. h__aplg second-stage larvae were collected on a 400-mesh‘sieve. Samples were stored at 5—7 C until microscopic quantitative population estimates were made. 3 of soil Final nematode population densities are reported as number per |00 cm or number per |.0 g of root tissue. Absolute densities can be calculated from these data and the final root growth measurements. This data reporting procedure was used for all experiments. 3.I.2 Influence of the date of M. hapla inoculation on the ontogeny of two cultivars of Q. carota Initial Procemre md Growth Conditions—Muck soil (coarse aggregate of organic material) was obtained from the MSU Muck Research Farm in Bath, 22 Michigm, and steam sterilized (4h at 88 C). Seventy-two clay pots (22.86 cm diameter) were washed and steamed (3h at I2l C) prior to use. All the 3 of steamed muck soil. One hole was made containers were filled with 4000 cm l.27 cm deep in the soil for planting in the center of each pot. Two seeds of Q. gm (cv Spartan Premium) were placed in the holes in each of 36 containers of sterilized muck. Two seeds of Q. 9% (cv Gold Pak) were then placed in the holes in each of the remaining 36 containers of sterilized muck. Each M. M inoculation date for both cultivars was replicated 6 times. M. M eggs were obtained from Q. gar—013 maintained in the MSU Nematology Greenhouse using sodium hypochlorite (NoCL) extraction (4|). M. 99m eggs were added at the rate of 4,800 eggs/pot to six pots of each cultivar at plmting md to six pots each week for 4 weeks. Each week a fresh supply of M. Mom was obtained to assure nematode viability. To introduce M. M into the root zone, a hole was made 2.5 to 3.5 cm deep, l.27 Cm from the plmt. The six additional pots of each cultivar were left as non-treated control plmts. The plants were maintained in the MSU Nematology Greenhouse (January 6, I977, to March l7, I977) under l6 hours of light and watered daily. Greenhouse air temperatures ranged from I3.9 C to 34.4 C with an estimated mem of 22.7 C. Relative humidity ranged from 4 to 70 percent with m estimated mean of 20 percent. The plants were fertilized 28 days after seeding with Rapid Gro Greenhouse Fertilizer' (2 tablespoons/gal). Insects were controlled by a spray of Malathion (I tablespoon/gal) at 2|, 42, and 63 days after plmting. When the second seed germinated, it was not roughed. l-la’vesting aid Evaluation ProcechresuAll plants were harvested 70 days. after seeding. Six replicates from each of the five inoCUIation dates plus the 23 controls were harvested for each cultivar. Soil and roots were removed from the pots intact and placed on paper for separating. Loose soil was shaken from the taproot did the root system. The remaining soil was washed from the roots using a gentle stream of cool tq) water. The plants were placed in plastic bags for later observations. Soil (I00 cm3) was randomly collected for evaluation of M. Lam population densities. Each plant was evaluated for shoot height, taproot length, fresh weight of the shoot, fresh weight of the tqaroot, fresh weight of the lateral roots, leaf surface area, marketability index, root gall index, number of M. ERIE/gram of lateral root, number of M. 10% eggs/gram of lateral root, number of galls per one randomly selected lateral root md number of M. M per one randomly selected lateral root. Soil samples were used to evaluate soil population densities of second-stage larvae of M. Lam. Shoot height was measured before harvesting the plants. Taproot length was measured after washing the root system. The tqaroot was considered to be the enlarged storage area of the main root. Fresh weight of the shoots, taproot md lateral roots were obtained by direct weighing on a one-place Mettler balance. Shoot surface area was measured on a Li-Cor Model Li-3000 Portable area meter. Marketability index was determined by placing freshly washed plants in categories based on growth md appearance. The index ranges from I to 3, with I representing marketable, 2 representing processing quality and 3 was non-marketable. The second—stage larvae md eggs of M. M were extracted from one gram of Q. c_arm roots using the gyratory shaker technique described by Bird (IQ) for 72 hours at I25 rpm. A 500 mesh sieve was used to collect both larvae and eggs. The centrifuge flotation technique (46) was used for soil 24 analysis using a 400 mesh sieve to collect M. Msecond-stage larvae. Samples were stored at 5-7 C until microscopic quantitative population estimates were made. One lateral root was selected at random for staining (77) for microscopic examination and quantification of galls and M. h_aglg_ associated with the root. All root systems were evaluated for galling by floating the roots in a shallow tray of water. The root-gall index ranged from I to 6 (I = root system free of galls, 2 = 0-l0% roots galled, 3 = l l-30% roots galled, 4 = 3I-70% roots galled, 5 = 7I-90% roots galled, 6 = 9l-l00% roots galled). 3.I.3 Effect of M. hapla on Q. carota ontogeny under two temperature progressions hitial Procechre aid Growth Conditions—Growth of Q. £219 (cv Gold Pak) was studied under two soil temperature progressions with md without M. M. The regimes were designed to simulate temperature conditions associated with early and late planting in Michigan. Muck soil (coarse aggregate of orgmic material) was obtained from the MSU Muck Research Farm in Bath, Michigm, and steam sterilized (4 h at 88 C). Forty-eight clay pots (I5.24 cm diameter) were washed md steamed (3h at |2I C) prior to use. All the containers were filled with l500 cm3 of steamed muck soil. Q. M seeds were pre-germinated for 5 days at room temperature (c_a 20.0 C). Germinated seeds with root radicles of 5 mm were selected for planting. One pre-germinated Gold Pak seed was planted l.27 cm deep in the center of each of the 48 pots filled with steamed muck soil. Each temperature treatment was replicated 6 times. M. M eggs were obtained from Q. ggr_o_t_g maintained in the MSU Nematology Greenhouse using the sodium hypochlorite (NaCI) extraction (4|). M. M eggs were added to half of the 48 pots at the rate of 7,500 per pot. 25 The inoculum was added to the same hole the.seed was placed in. This inoculation rate supplied on initial population of 500 eggs/l00 cm3 of soil. Half of the pots for each treatment were placed in each of two Esco temperature tanks in the MSU Nematology Greenhouse (November 2|, I977, to January 3, I978) under I6 hours of light md watered daily. The early growing season simulation started at 9 C and the late growing season simulation at l8 C. Both regimes were increased l-2 C every 7 days: Date Cold Regime Warm Regime Neverrber 2|, I977 9°C l8°C Noven'ber 28, I977 Io°C l9°C December 5, I977 I2°C 20°C December I2, I977 |4°C 22°C December l9, I977 I6°C 24°C December 26, I977 I8°C 25°C Jmuary 2, I978 Final Harvest Final Harvest No fertilizer was applied prior to planting or during the 42 day experiment. Insects were controlled by a spray of Malathion (I tbsp/gal) at I4 md 28 days after planting. Harvest'ng md Evaluation Procedures—Six replicate plants of each treat- ment from both regimes were randomly selected for harvest at 2| and 42 days after planting. The soil md roots were removed from the pots intact md placed on paper for separating. The shoot and root system was removed from the soil using forceps, washed in a container of cool tap water did placed in a petri-dish. 26 Soil (I00 cm3) was randomly collected md set aside for evaluation of M. hapla population densities. Each plant was evaluated for shoot height, taproot length, taproot quality (marketability index), fresh weight of the shoot, fresh weight of the root system, shoot surface area, root surface-area, number of galls on the taproot, number of galls on the lateral roots, and the number of M. M in the stained root system. Soil samples were used to evaluate soil population densities of second-stage larvae of M. h_ang. Shoot height was measured before harvesting the plants. Taproot length was measured after washing the root system. The taproot quality was deter- mined through a marketability index by placing freshly washed plants in categories based on growth and appearance. The index ranges from I to 3, with | representing marketable, 2 representing processing quality md 3 was non- marketable. Fresh weight of the shoot and root system were obtained by direct weighing on a four-place Mettler balance. Surface creas were measured on a Li- Cor model Li-3000 portable area meter. The number of galls on the taproot and lateral roots were microscopically observed by floating the roots in a shallow tray of water. The root system was then stained (77) to observe M. M within the roots. The centrifuge flotation technique was used for soil analysis using a 400 mesh sieve to collect M. M second-stage larvae. Samples were stored at 5-7 C until microscopic quantitative population estimates were made. 3.2 Solanum tuberosum 3.2.I Pathogenicity of M. hapla to S. tuberosum roots and tubers hitial Procedure and Growth Conditions—One seed piece of Norchip, the second leading commercial S. tuberosum cultivar in Michigm (l5.2% of acreage), 27 was planted in each of'48 tile containers of sterilized muck soil. Weight of the seed pieces ranged from 69.5 to 92.7 g with an estimated mean of 83 g. The containers were clay drainage tiles, 20.3 cm inside diameter by 32.4 cm tall. Nylon screening was taped to the tiles to provide a bottom. All tiles were steam sterilized for 2 hours prior to use. The muck soil used was obtained from the MSU Muck Farm near Bath, Michigan. All 48 of the tile containers were filled 3 of unsterilized muck soil. The filled containers with approximately I x IO“ cm were steam sterilized for 4 hours. Holes were made 3 to 4 inches deep with a hand trowel for planting. Two initial population densities of M. Lam were used: a nematode-free control md 500 eggs per I00 cm3 of soil (50,000 eggs/tile). Half of the water suspension of M. Lam eggs was added before putting in the seed piece. The rest of the inoculum was added on top of the seed before covering it with soil. The inoculum was obtained by using the sodium hypochlorite (NaCI) method (4|) to extract eggs from tomatoes maintained in the MSU Nematology Greenhouse. Each treatment consisted of 24 tile containers. The plants were maintained under I4 hours of light and watered daily. Greenhouse air temperatures ranged from 8.3 C to 34.4 C with m estimated mem of 2l.8 C. Humidity ranged from I0 to 75% with an estimated mean of 23%. Container soil temperatures ranged from I0.6 C to 2|.I C with m estimated mem of I4.6 C. No fertilizer was applied prior to plmting or during the I I9 days of growth. Harvesting md Evaluation Procerbres—Five replicates from each treat- ment were randomly selected for each of 4 harvest dates: 77, 9|, |05 and I|9 days after planting. Prior to harvesting, 2 sets of plastic bags, flasks, md test tubes were labeled for processing soil samples, storage of S. tuberosum tubers, 28 root processing, and soil samples, respectively. Plastic containers were labeled for weighing shoot and root systems. First, all shoot systems were removed and weighed. Shoot systems were discarded after weighing. Soil and root systems were then separated from the tile using a large knife. All of the soil and root systems were removed from the pots intact and placed in a wire-mesh basket for separating. With a sifting motion, the soil was removed from the roots and tubers. Then roots md tubers were removed from the basket. Remaining soil was then washed from the roots and tubers using a gentle stream of cool water. Washed tubers were placed in pre-labeled plastic bags. Washed root systems were placed in pre-ldaeled plastic containers. Soil samples containing I00 cm3 of randomly collected soil were placed in plastic bags for evaluation of M. Lam population densities. Each S. tuberosum plant was evaluated for shoot, root md tuber fresh weight, total number of tubers, root galling index, tuber surface quality index, identification of nematodes in the tubers, average fresh tuber weight, number of nematodes and eggs per LO 9 of roots md number of nematodes per l00 cm3 of soil. Fresh weight of shoots, roots md tubers was made by direct weighing. A one-place Mettler balance was used. Root gall index ranged from I to 6. One designated a gall-free root system. Six designated that 90-l00 percent of the root system expressed galling. A tuber quality index was used to determine appearance. The index ranged from I to 6. One designated a perfect tuber skin quality. Six designated that 40-50 percent, or more, of the tuber surface area contained raised lenticels or cracked lesions. Positive identification was made using thin cross-sections under lesioned areas. Cross-sections were stained; then microscopic verification was made. One gram of root was processed for 29 nematodes md eggs by the shaker technique. The centrifuge flotation technique was used for soil analysis. All second-stage M. hapla larvae were collected on a 400 mesh sieve. Samples were stored at 5-7 C until microscopic qumtitative population estimates were made. 3.3 Apium graveolens md Allium cepa 3.3.I Early-season ontogeny of A. graveolens and A. cgpa infected with M. hgla Initial Procechre md Growth Conditions--Muck soil was obtained from the MSU Muck Research Farm in Bath, Michigan, and steam sterilized (4 h at 88 C). Two hundred clay pots (I5.2 cm diameter) were washed md steamed (3 h at l2l 3 of steamed muck C) prior to use. All the containers were filled with l500 cm soil. Holes were made l.27 cm deep in the soil for planting md inoculating. Four to six seeds of A. graveolens were placed in the holes in each of the remaining I 00 containers of sterilized muck soil. M. M eggs were obtained from Q. m maintained in the MSU Nematology Greenhouse using sodium hypochlorite (NoCl) extraction (4|). M. hgglg eggs were added to the seed in the hole before covering with soil. Four initial population densities of M. M (0, 50, 500, md 5000 eggs/pot) were each replicated 25 times. The plants were maintained in the MSU Nematology Greenhouse (March 24, I977, to April 28, I977) under l4 hours of light and watered daily. Greenhouse air temperatures ranged from II to 36.6 C with an estimated meén of 23.6 C. Relative humidity ranged from 4 to 99% with an estimated mean of 43.5%. No 3O fertilizer or pest control chemicals were applied prior to planting or during the 35-day experiment. Plants were thinned daily to one per pot as extra plants emerged. Nematode loss due to thinning was assumed to be negligible. I-h'veeting aid Evaluation ProcedJres—Five replicate plants from each of the four initial nematode density treatments were randomly selected for harvest every 7 days. The soil and roots were removed from the pots intact and placed on paper for separating. Each germinated seed, or plant md root system, was removed from the soil using forceps, washed in a container of cool tq) water and placed in a 50 ml beaker. Soil (|00 cm3) was randomly collected md set aside for evaluation of M. M population densities. Each shoot was evaluated for number of true leaves, fresh weight, dry weight, number of root galls, number of lateral roots (A. graveolens) and number of rootlets (A. c_egg). Soil samples were used to quantify soil population densities of second-stage larvae of M. M. The number of true leaves, fresh weight and root obServations were made prior to drying. Root systems were evaluated by floating roots in a shallow tray of water. Fresh weights of the plants (shoot md root intact) were obtained by direct weighing on a balance. Dry weights of the plants were obtained by drying (48 hours) in an oven at I00 C. All measurements were +0.I mg. The centrifuge flotation technique (46) was used for soil analysis. All M. M second-stage larvae were collected on a 400 mesh sieve. Samples were stored at 5-7 C until microscopic qumtitative population estimates were made. 3.3.2 Influence of four population densities of M. hapla on the ontogeny of A. graveolens and A. cgpa Initial Procedure md Growth Conditions—Muck soil (coarse aggregate of orgmic material) was obtained from the MSU Muck Research firm in Bath, 31 Michigm, and steamed (4 h at 88 C). Eighty-four clay pots (20.3 cm diameter) were washed and steam sterilized (3 h at I2I C) prior to use, and filled with 4000 cm3 of steamed muck soil. Holes were made 2.5 cm deep (seeds) or deeper (transplants) in the soil for planting md inoculating. Four to six seeds of A. graveolens were placed in the holes in each of 20 containers of sterilized muck soil. One A. graveolens transplant was placed in the hole in each of 32 containers of sterilized muck soil. The weight of the transplants ranged from L6 to 3.6 g G = c_g 2.4 g). The height of the transplants ranged from I2.9 to I6.2 cm (E = c_a I4.6 cm). Two seeds of A. c_em (cv Downing Yellow Globe) were placed in the holes in each of the remaining 32 containers of sterilized muck soil. M. h_aEI£ eggs for inoculum were obtained by the sodium hypochlorite (NaCl) method from Q. gm maintained in the MSU Nematology Greenhouse. M. M eggs were added to the seed (or transplant roots) in the hole before covering with soil. Four initial population densities of M. Law (0, 50, 500, and 4000 eggs/pot) were used. Each treatment was replicated 8 times (A. Egg did A. graveolens transplants) and 5 times for A. g aveolens grown from seed. The plants were maintained in the MSU Nematology Greenhouse (March 24, I977, to July 7, I977) under l4 hours of light and watered daily. Greenhouse air temperatures ranged from II to 37.2 C with an estimated mem of 25.9 C. Relative humidity ranged from 4 to 99% with an estimated mean of 43%. No pest control chemicals were applied prior to planting or during the l05-day experiment. The plants were fertilized on day 6 with chid Gro Greenhouse Fertilizer. Plants were thinned daily to one plant per pot as extra plmts emerged. Nematode loss due to thinning was assumed to be negligible. 32 Harvesting md Evaluation Procecbres—AII plants were harvested |05 days after seeding. Eight replicates from each of the four initial nematode density treatments (for the A. graveolens transplants did A. c_epg) were harvested. Five replicates from each of the four initial nematode density treatments, grown from A. graveolens seed, were harvested. Soil and roots were removed from the pots intact md placed on paper for separating. Loose soil was shaken from the root system. The remaining soil was washed from the roots using a gentle stream of cool tap water. The plants were placed in |000 ml beakers. Soil (I00 cm3) was randomly collected for evaluation of M. M population densities. Each plmt was evaluated for shoot height, fresh weight of the shoots, fresh weight of the roots, dry weight of the shoots, dry weight of the roots, root gall index, marketability index, number of nematodes per one stained lateral root, md number of nematodes per gram of root. A. (5% included the evaluation for fresh md dry weight of the bulb md bulb diameter. Soil samples were used to evaluate soil population densities of second-stage larvae of M. h_aflc_I. All root systems were evaluated for galling by floating the roots in a shallow tray of water. The gall index ranged from I to 6 (I = root system free of galls, 2 = 0-I0% roots galled, 3 = l l-30% roots galled, 4 = 3l-70% roots galled, 5 = 7l-90% roots galled md 6 = 9l-I00% roots galled). Fresh weights of the shoots, roots and bulbs were obtained by direct weighing on a one-place Mettler balance. . Plant height was measured before harvesting the plants. The marketability index was determined by placing freshly washed plants in categor- ies based on growth md appearance. The index ranged from I to 3, with I representing a marketable condition, 2 representing processing quality and 3 being considered non-marketable. Dry weights of the shoots, roots, and bulbs 33 were obtained by drying (48 hours) in an oven at I00 C. All dry weights were made on a balance (+0.l mg). One randomly chosen lateral root was selected for staining (77) for microscopic observation. Nematodes were extracted from either 5.0 g (A. graveolens) or I.0 g (A. c_em) of roots using the gyratory shaker tectnique described by Bird (l0) for 72 hours at l25 rpm. The centrifuge flotation technique was used for soil malysis. For both the shaker md centrifuge flotation technique, M. M larvae were collected on a 400 mesh sieve. Samples were stored at 5-7 C until microscopic qumtitative population esti- mates were made. 4. RESULTS 4.I Daucus carota 4.I.l Early-season ontogeny of Q. carota infected with M. hapla The shoot system of cv Spartan Premium was significmtly (P = 0.05) larger that that of cv Gold Pac (Fig. I). Plant emergence occurred between degree-day I l I and 223. M. M had a greater detrimental influence on the ontogeny of Q. Mg, cv Gold Pac, than on cv Spartan Premium. Infection by M. M resulted in 01 inhibition of cv Gold Pac shoot weight (Fig. I). The shoot weight of cv Spartan Premium was not influenced by M. M (Fig. 2). Cv Gold Pac exhibited shoot weight differences at degree-day 556 between the nematode-free plants did the lower level of M. h_ogl_g_ infection. By degree-day 556, all cv Gold Poc plants in the higher M. h_ap|_a level never emerged or had died. Cvs Gold Pac and Spartan Premium expressed the some differences in shoot surface area as for shoot weight (Figs. 3 6r 4). The shoot height of cvs Gold Pac and Spartan Premium both were detrimentally influenced by M. M at degree-day 223 (Figs. 5 8r 6). This phenomenon continued with cv Gold Pac throughout the harvest period. By the second harvest date, however, cv Spartan Premium was not influenced by M. M. M. h_ng0 had no significmt influence on the weight or surface area of the roots of either cultivar (Figs. 7-l0). Root weights at all three M. h_ap_lg levels followed the some growth patterns. Root system development md accumulation of weight was initiated at about 445 degree-days in the presence or absence of M. h_a£lg. The surface area of the root systems followed the patterns of the root wieghts. M. h_apl_a damaged the taproot of cv Gold Pac. The reduction in taproot 34 35 E! O.- 0 Daucus carota, O a“ cv Gold Pac 9’3 g; ‘ «>4xisnluquq/uxienrlum g $_ .440 1r. lupin/100 orn’ soil ,_ o m—Nunatodofras o o I m z 8 6d 2 ./’ 6‘1 5 I o 111 22:. 33. 4'45 2% DEGREE DAYS AT HARVEST Figure 1. Influence of Meloidogyne hapla at three initial population densities on the shoot weight of Daucus carota (cv Gold Pac). MEAN SHOOT WEIGHT (0) Figure 2. 1 l 1.0 0.5 l 36 Daucus carota cv Spartan Premium 0-60 1!. haplo/ 100 cm' soil A-24O I. hapla/100 cm’ soil El-Nemotode free c30-0 ' Tr F I r 1 1 1 1 223 334 445 556 558 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three initial population densities on the shoot weight of Daucus carota (cv Spartan Premium). 37 -l p Daucus carota 2 .. 9, m cv Gold Pac U) B O I (1') LI. 0 0-60 It. hapla/100 em' soil I5 .—2«31LIMquq/ux>em'emI % N m—Nematodefreo 8 If. D: D (I) 2 d D l T I l o 111 223 334 445 556 DEGREE DAYS AT HARVEST Figure 3. Influence of Meloidogyne hapla at three initial population densities on the shoot surface area of Daucus carota (cv Gold Pac). MEAN SURFACE AREA or SHOOTS (cv”) Figure 38 Daucus carota cv Spartan Premium GPSOIULhaphuHOOINN'mfil' a-24O ll. hapla/ 100 cm’ soil lD-NenKNDde‘flee I ' r r I r 111 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three ini- tial population dénsities on the shoot sur- face area of Daucus carota (cv Spartan Premium). 39 '3- Daucus carota m cv Gold P00 0‘) 0-60 1!. hapla/100 crn' soil s—24O 1!. hapla/100 cm’ soil ’2‘ 5 g- El-Nematodefree $2 DJ 3: j— <3. <3 I roe 0) II. :2 m_. o I I ' I I fl 0 111 223 334 445 556 DEGREE DAYS AT HARVEST Figure 5. Influence of Meloidogyne hapla at three initial population densities on the shoot height of Daucus carota (cv Gold Pac). MEAN SHOOT HEIGHT (MM) 40 Daucus carota. cv Spartan Premium 0-60 1!. hapla/100 cm’ soil A—24O 1!. hapla/100 cm' soil III-Nematode free Figure 6. T I l I l l I 111 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three ini- tial population densities on the shoot height of Daucus carota (cv Spartan Premium). 0.05 0006 I 0-04 I 0.03 MEAN ROOT WEIGHT (6) 0-02 0.01 41 Daucus carota cv Gold Pac cr4x>1c hopkyWHXIon? «Ml .m—240.flllkqflo/100 cnflmfil ErJWNndmac'flae op.00 Figure 7. I I I I . I 111 223 334 445 556 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three ini- tial population densities on the root weight of Daucus carota (cv Gold Pac). 42 HEHN ROOT HEIGHT (G) 0: o- .I Daucus carota. cv Spartan Premium “2 D- . o—60.U2hnpkyHOD an’ecn 5-240 1. hold/100 cm’ soil EI-Nematode free *2 OH .I D 5" I r I I 0 1 1 ‘l 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Figure 8. Influence of Meloido ne hapla at three initial population densities on the root weight of Daucus carota (cv Spartan Premium). 43 ‘9- 1 Daucus carota. "5 4 cv Gold Pac r2 :2, c: c: a: . ES 0P60.UlhapkuHOOImn'sdl fi A~24O ll. hapla/100 cm’ soil % m-Nematodofraa ‘6‘ E a: 8 "a 2 «I -I 4 /7 '9 'o I I I I 1 o 111 223 334 445 556 DEGREE DAYS AT HARVEST Figure 9. Influence of Meloidogyne hapla at three ini- tial population densities on the root sur- face area of Daucus carota (cv Gold Pac). S'I '2‘ c, 53% V m d j— C) CD a: u. (D E e- B E I: :1 a) 3 :2 *d .1 °o Figure I0. 44 Daucus carota. cv Spartan Premium ID-BO.M2)Hnfla/IOO cwfaum 5-24O.Hlluqflo/1OO on? udl arJNNnathIflae . _r 1 I I I 111 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three initial population densities on the root surface area of Daucus carota (cv Spartan Premium). 45 length was greater as the initial population density of M. _hgglg increased (Fig. ll). Spartan Premium showed M. Lam induced taproot length reductions early in the growth period at ill and 223 degree-days (Fig. l2). At the next three harvest dates there was a slight increase in taproot length in the presence of M. M. This increased growth response in cv Spartan Premium reversed after 556 degree days, and M. M reduced taproot length. Taproot quality of both cvs Spartan Premium and Gold Pac was poor in the presence of M. M (Table I). Cv Spartan Premium had a higher percent of non-marketable taproots at the higher M. M level. Root galls caused by the low population density of M. h_ap_lg_ began to be visible on the tcproots of both cultivars between lll md 223 degree-days (Figs. l3 & l4). At the high pop- ulation density of M. h_aglg, galls were not observed on cvs Gold Pac and Spartan Premium roots until after 223 degree-days. No galls mpeared on the lateral roots of either cultivar until 334 degree days. Called lateral roots occurred mainly at the higher level of M. M. No M. h_agl_a_ were observed in stained root systems of cv Spartm Premium until degree-day 334, and degree-day 445 for cv Gold Pac. Juveniles of M. M were recovered from soil until the plants were transplanted into sterilized soil (degree-day 223). No nematodes were found in the soil during the remainder of the experimental period. 4.I.2 Influence of the date of M. hapla inoculation on the ontogeny of two cultivars of Q. carota M. hapla had a detrimental influence on the ontogeny of the shoot systems in both cultivars of Q. carota (Figs. l5 8. l6). The shoot system of cv Spartan Premium was heavier than that of cv Gold Pac throughout the experimental 80 ‘4 MEAN TAPROOT LENGTH (MM) o~60.u;hapuynoo un'sdl A-24-0 1!. hapla/100 cm’ soil ‘9‘ [El-Nematode free 46 Daucus carota cv Gold Pac Figure ll. I I I I a 111 223 334 445 555 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three initial population densities on the taproot length of Daucus carota (cv Gold Pac). 47 Daucus carota. cv Spartan Premium I arJMJJL haphyWHKDCHElflm a-240.llluquq/HX)cnf:ufl ‘3‘ m—Nundbdofnu A :5 :5 V Ea: E |— OJ 23 g. E 53- .l I34 N °o Figure l2. I ’n’ I I I I I 111 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three initial population densities on the taproot length of Daucus carota (cv Spartan Premium). 48 Table 1. Influence of Meloidogyne hapla at three initial population densities on the tap root quality of Daucus carota (cV'Spar- tan Premium and Gold Pac), recorded for seven harvest dates (measured in degree-days, DD). Cultivar Taproot Quality Indexl Initial Population DD DD DD DD DD DD DD Density 111 223 334 445 556 668 779 Spartan Premium 0 1.00a2 1.00a 1.0a 1.0a 1.0a 1.0a 1.0a 60 2.00b 1.70a 1.7a 1.0a 2.0b 3.0b 3.0b 240 1.00a 1.33a 1.5b 1.5b 2.7b 3.0b 3.0b Gold Pac 0 1.00a 1.00a 1.0a. 1.0a 1.0a 60 1.33a 1.33a 1.0a 1.3a 2.0b 240 1.50a 1.703 2.2b 2.0a 3.0a lTaproot quality: 1 represents marketable, 2 represents processing quality and 3 represents nondmarketable. 2 Column means followed by the same letter are not significantly different (P = 0.05) according to the Student-Newman-Keuls Multiple Range Test. 2.0 I MEAN NUMBER OF CALLS PER TAPROOT 0.6 110 49 Daucus carota. cv Gold Pac 0-60 1!. hapla/ 100 cm’ soil A-24O H. hapla/ 100 cm’ soil ln-Nenuflbdo'fieo ‘30.0 Figure l3. 111 223 334 445 556 DEGREE DAYS AT HARVEST Influence of Meloidogyne hapla at three ini- tial population densities on galls per tap- root on Daucus carota (cv Gold Pac). m.. w— ,— c3 c: I: E a: 'v‘ uJ a. 3 (9 E3 ”d a: u; a: :5 :3 2: a “‘ :2 ch Figure l4. 50 Daucus carota. cv Spartan Premium 0-60 1!. hapla/100 cm’ soil a-240 I. hapla/100 cm’ soil III-Nematode free 111 223 334 445 556 668 779 DEGREE DAYS AT HARVEST Influence of Meloidogyne ha la at three initial population densities.on ga 5 per taproot on Daucus carota (cv Spartan Premium). MEAN SHOOT HEIGHT (MM) Figure l5. 250 a 4 200 l 51 Daucus carota. ? . / cv Spartan Premium I, Inoculation date ,9] Day 0 Day 7 / Day 14 / / Day 21 / Day 28 / Nematode free / / / E] 0 A 0 4 X :1 2i 25 3% 4% 45 5% all 75 DRY HT HEHSUREHENT Influence of Meloidogxne hapla on shoot system height of Daucus carota (cv Spar- tan Premium) due to inoculation date. 52 200 I ., Daucus carota. / cv Gold Pac ,",’ Inoculation date Day 0 Day 7 Day 14 Day 21 Day 28 Nematode free N+0>OB MEAN SHOOT HEIGHT (MM) 5’ T l l WT F l . 7 14 21 28 35 42 49 56 B3 70 DRY RT MERSUREMENT Figure l6. Influence of Meloidogxne hapla on shoot system height of Daucus carota (cv Gold Pac) due to inoculation date. 53 period (Fig. l7). Only M. _thlg inoculated at day 0.resulted in a reduction in shoot weight of cv Spartan Premium, whereas M. M inoculated up to day l4 after seeding resulted in a reduction of shoot weight in cv Gold Pac. The leaf area of the shoot systems of both cultivars followed the same pattern as shoot weights (Fig. l8). M. M had a detrimental influence on the marketable quality of both cultivars. The length of the taproot was greater for cv Spartan Premium than for cv Gold Pac throughout the experiment (Fig. l9). M. EELO appeared to affect cv Spartan Premium only when the nematode was added at day 0. lnoculations from day 7 to day 28 did not influence the taproot length of cv Spartan Premium. M. h_apM, however, inhibited the length of cv Gold Pac taproots when added up to 28 days after planting. Taproot weight increased greatly from day 0 to day 7 for cv Spartcn Premium with a slight tapering off of weights after day l4 (Fig. 20). Cv Gold Pac expressed a gradual increase in taproot weight from day 0 to day 2 l. M. M had a greater negative impact on the taproot of cv Gold Pac than on cv Spartan Premium. Lateral root weight of Q. m cv Gold Pac was influenced by M. Lam through day 7 (Fig. 2|). After day l4, no significant differences could be detected between the weights of average lateral roots for either cultivar. Both cultivars exhibited the same pattern of taproot marketability (Table 2). The further away from planting that infection occurs, the less M. M is able to reduce taproot quality. The number of galls per lateral root (Fig. 22), and the percent of roots galled (Table 2) decreased when infection occurs further from planting. The pattern was the same for both cultivars. As the day of inoculation moved 54 NERN SHOOT HEIGHT (Gil) // .Danumus carota k 3* Spartan premium ‘ In Gold pac O I l l l fl 0 7 14 21 26 control DRY OF INOCULRT ION Figure l7. Influence of Meloidogyne hapla on shoot weight of Daucus carota (cv Spartan Pre- mium and GOTd”Pac)'dUe to inoculation date. 55 4?!) MEAN SHOOT SURFACE AREA (CM!) .Damunas carota “ 3* Spartan premium In Gold pac o I I I I fl 0 7 14 21 28 control DRY OF INOCULRTION Figure l8.' Influence of Meloidogyne hapla on shoot surface area of Daucus carota (cv Spartan Premium and Gold Pac), due to inoculation date. 56 L MEAN TAPROOT LENGTH (MM) 5 l fl/ IhrucnusIGarota. In-I . N 3" Spartan premium q II] Gold pac Q I I I I I 0 7 14 21 28 control DRY OF INDCULRTIDN Figure 19. Influence of Meloido Ine hapla on taproot length of Daucus carotg_(cv Spartan Premium and Gold Pac), due to inoculation date. 57 Oq N .Ig-I ’\ .. 2 o d V 33 . Ihrucnuslcarota; 3 o x Spartan premium F— ..‘ ((C2) El Gold pac a: I 2 . )1 w- / p / /A\ / . J!,,/' \\. // 'i / / ,r”!/ it” o I I I I T —I o 7 14 21 28 annual DRY 0F INOCULRTIDN Figure 20. Influence of Meloidogxne ha la on taproot weight of Daucus carota (cv partan Premium and Gold Pac), due to inoculation date. 58 mi ’5 8 ’5 S2 uJ 3: '5 O c: If S 2 CV. llaaumus cnmrota; 3* Spartan premium “ El Gold pac . o I I I I I o 7 14 21 28 control DRY 0F INOCULRTIDN Figure 21. Influence of Meloidogyne hapla on lateral root weight of Daucus carota‘ch Spartan Premium and Gold Pac), due to inoculation date. Table 2. Influences expressed, due to the inoculation day of. Meloidogygeghapla, on taproot quality and root galling t 59 index of Daucus carota (cv Spartan Premium and Gold Pac). Day of inoculation with M. hapla l Taproot Quality Root Galling? Spartan Gold Spartan Gold Premium Pac Premium Pac 0 2.83213 3.0a 4.0a 4.73. 7 1.83a 2.7ab 3.8a 3.5b 14 1.50a 2.3ab 3.8a 3.7b 21 1.00a 2.0bc 3.68 3.0b 28 1.67a 1.3c 2.8b 3.5b Control 1.30b 1.3c 1.0b l.0c 1Taproot quality: 1 represents marketable, 2 represents processing quality and 3 represents non-marketable. 2Root gall index: galled. 3 Column means followed by the same letter are not significantly 1 = free of galls, 2 - 0-102 roots galled, 3 = ll-3OZ roots galled, 5 = 71-90% roots galled, 6 = 91-1002 roots different (P = 0.05) according to the Student-Newman-Keuls Multiple Range Test. MEAN NUMBER OF CALLS/LATERAL ROOT 60 19amunus'cxrrota; x Spartan premium In Gold pac Figure 22. 7 1 4 2I 2D control DRY 0F INOCULRTION Influence of Meloidogyne hapla on galls per lateral root on Daucus carota (cv Spartan Premium and Gold Pac), due to inoculation date. 61 further away from day 0, fewer galls were produced. ‘This decrease in symptom expression may have been due to the lack of time for the plant to develop these symptoms. Both cultivars were good hosts for reproduction of M. Mafia; however, cv Gold Pac appeared to be a slightly better host than cv Spartan Premium, allowing M. _thlg to reach higher soil population levels at inoculations of day 0 and day 7 (Fig. 23). The decreasing trend of soil populations is believed to be due to lack of degree-days to complete the life cycle prior to the end of the experimental period. The number of nematodes in on average lateral root was greater for cv Spartan Premium at day 0 and day 7 thm for cv Gold Pac (Fig. 24). lnoculations at day l4 to day 28 resulted in cv Gold Pac having greater M. h_agl_g population densities in the roots. The number of nematodes extracted from one gram of roots was slightly higher at day 0 for cv Spartan Premium than for cv Gold Pac, but then nematode levels dropped rapidly in cv Spartan Premium to bring it below cv Gold Pac levels until harvest (Fig. 25). When M. Lam eggs were extracted from one gram of root tissue, cv Gold Pac had greater population densities of M. _h_ap_lg from day 0 to harvest than cv Spartan Premium (Fig. 26). Again, more eggs are present from inoculation day 0 because of the accumulation of more degree-days. The higher production of eggs associated with cv Gold Pac than cv Spartan Premium was expected because it appears to be a better reproductive host for M. M- 4.l.3 Effect of M. hapla on Q. carota ontogeny under two temperature progressions M. hapla under the warm temperature regime had detrimental influences on the growth of Q. carota cv Gold Pac (Plate 2) during the first 2| days. At l 2 I MEAN NUMBER OF NEMATODES/IOO CC SOIL 4 1 62 \ Daucus carota \ x Spartan premium \ E] kad pac Figure 23. 7 1 4 21 2 control DRY or INOCULRTION Influence of Meloidogyne hapla on soil popu- lation levels from Daucus carota (cv Spar- tan Premium and Gold Pac), due to inoculation date. MEAN NUMBER OF NEMATODES/LATERAL ROOT me 63 Ikruxnuslcarota. 111 Spartan premium / \ In Gold pac Figure 24. I I I 7 14 21 28 mm, DRY 0F INDCULRTIDN Influence of Meloidogyne hapla on nematodes per lateral root on Daucus carota (cv Spar- tan Premium and Gold Pac), due to inocula- tion date. 180 MEAN NUMBER OF NEMATODES/GM OF ROOTS 64 \ Lhruxnws cnzrota; \ as Spartan premium 1:] Gold pac Figure 25. 7 II 21 26 DRY 0F INOCULRTION cmnbm Influence of Meloidogyne hapla on nematodes per gram of roots on Daucus carota (cv Spar- tan Premium and Gold Pac), due to inocula- tion date. 200 ”I 65 o . F-ffl‘ Zhuucus carota 8 \ . an It as Spartan prequm 2‘5 \\ In Gold pac :5 \x 8 “K (I) \ . 8 A LIJ §d \ / u. C) c: DJ on :5 :3 2: 22:3‘ °o 7' II 21 25 control DRY 0F INOCULRTION Figure 26. Influence of Meloidogyne hapla on eggs per gram of root on Daucus carota (cv Spartan Premium and Gold Pac), due to inoculation date. Plate 2. 66 Influence of Meloidogyne M and two soil temperature regimes on the ontogeny of Daucus carota (cv Gold Pac) during the first 2| days of growth. Starting top row, left to right: I) Average growth of Q. gm under warm regime free from M. ERIE: 2) Average growth of Q. apt—a under warm regime in the presence of M. M- 3) Normal growth obtained after three weeks under the cool regime without M. Mg. 4) Growth of Q. m affected by M. h_aglg under the warm regime for three weeks. 5) Normal growth increased after three weeks under the warm regime without M. M- 6) M. @La did not express detrimental symptoms when Q. c_gr__ota was grown under the cool regime. a I 3 WEEKS COLD TANK STIRILE a- I 3 WEEKS WARM TANK STIRILE 67 ~.‘ I 3 WEEKS WARM TANK INFESTED // )7 - t / _“ I 3 WEEKS COLD TANK INFECTED 68 days 2| md 42, the plants grown free of M. M under the warm temperature regime weighed significantly (P=0.05) more than plants grown under the cool temperature regime, or in the presence of M. M at either temperature regime (Fig. 27). A larger shoot system is expected due to rapid growth under warm soil conditions, but at the warm temperature, M. Mwas able to invade the plmt, causing a sigiificmt shoot weight inhibition. Shoot height was significmtly reduced by M. h_ggl_q under the warm temperature regime (Fig. 28). Plants grown under the warm temperature in the presence of M. _hgm could not be visually distinguished from Q. gar—otg grown under the cool regime or nematode—free conditions. This some significant difference between the warm control plants did the cool control plants along with both inoculated temperature regimes was present at both harvest dates for the surface area of the shoot systems (Fig. 29). The effect of M. M on the root system was different than for the shoot system. Infection by M. _thlg resulted in a significant increase in the weight of the root system under the warm regime (Fig. 30) at day 2|. By day 42, no significmt differences could be detected in my of the treatments. This early significant response was due to root galling at the warm temperature. The tap root length was significantly longer under the warm control regime at day 2| (Fig. 3|). Significmt tcproot length differences were not present at harvest on day 42. The impact was due to the ability of Q. c_g_ota to grow rapidly under a warm, nematode-free environment. The only significant difference in the surface area of the root system was observed on day 2| between the cool temperature controls md the warm temperature Q. gLotg grown in the presence of M. h_oglg (Fig. 32). This difference in surface area of the roots was not observed on day 42. “3 o- 4 i El 1. 0 o A p,\ l 2 0 V [—00 I H 9:: LIJ 3 I— a O O I (I) 9.. fig :3 2 d '7: O ‘2 ch Figure 27. 69 Daucus carota Nematode free 9-18°c Nematode free 18-25% M. Hapla 9-18’c l‘" M. Hapla 18-25°c // / / / / / / / / / / / / / / // / l” / / / / / / l / / / T 21 42 DRYS Influence of Meloidogyne hapla and two soil temperature regimes on the sfiOot weight of Daucus carota (cv Gold Pac). o o- d E El ed 0 o A MEAN SHOOT HEIGHT (MM) 70 Daucus carota Nematode free 9-18‘c / Nematode free 18-25°c /// M. Hapla 9-18‘c / M. Hapla 18-25% // O I j o 21 42 DRYS Figure 28. Influence of Meloidogyne hapla and two soil temperature regimes on the shoot height of Daucus carota (cv Gold Pac). 71 2'1 lhuuous cereal I! Nematode free 9-18‘c )0 . E1 Nematode free 18-25’c // A o M. Hapla 9-18‘c / "2 / 8 A M. Hapla 18-25'c / ' / 5 / a) *_ / / 8 / :r I ‘1’ / .4 / g / i, 0 '6‘ / ,z’ if I 1’ a: _ [I l/ a u: / x” a ’ ’ I 0 2t 42 DRYS Figure 29. Influence of Meloidogyne hapla and two soil temperature regimes on the shoot system sur- face are of Daucus carota (cv Gold Pac). 72 O N :51 IDauoue oaroflz i! Nematode free 9-18'c m Nematode free 18—25'c o M. Hapla 9-18’c 53 o ‘5‘ t M. Hapla 18-25‘c ,’ MEAN ROOT SYSTEM WEIGHT (GM) 0.1 4 0.06 cP-OO Figure 30. Influence of Meloidogyne hapla and two soil temperature regimes on the root system weight of Daucus carota (cv Gold Pac). 180 I MEAN TAPROOT LENGTH (MM) 73 Demons carota Nematode free 9-18'c // Nematode free 18-25‘c ,/ M. Hapla 9-18'c // M. Hapla 18-25'c / ”b 2i 42 DRYS Figure 3l. Influence of Meloidogyne hapla and two soil temperature renges on the taproot length of Daucus carota (cv Gold Pac). 74 ‘2 cu- Lhuucuurrmmrona « ! Nematode free 9-18’c E1 Nematode free 18-25’c ,; I :3; o M. Hapla 9-18'c ,7 :3 1’; 2 4 M. Hapla 18-25'c ,’/ O [I V ’/ IE .6 Ii‘ // /7 3 “2 1’ ._‘ 4! 5 I; o ’/ ‘f 17 0 I a {a // U 0-4 I, 2 " x’ u. 1’ a: I/ :3 )7 (n . ’7/ / I E ’7/ / I u? ’l ‘0- '9 °o 2i :2 DRYS Figure 32. Influence of Meloidogyne hapla and two soil temperature regimes on the root system sur- face area of Daucus carota (cv Gold Pac). 75 After 2| days the taproot quality of plants inoculated under the cool temperature regime was not significantly different from taproot quality of plants grown free of M. M (Table 3). By day 42, enough time elapsed to allow both M. M regimes to exhibit significant differences in taproot quality (Table 3). The dfility of M. Mom to invade Q. £912 roots md cause galling was significmtly (P = 0.05) greater in the warm temperature regime at day 2| (Figs. 33 8. 34). As the temperature in the cool temperature regime was raised, the differences between regimes in the amount of galling on the tcproot and lateral roots decreased. There was too much variation in the sample results to observe differences in the number of M. mm per l00 cm3 of soil in either temperature progression (Fig. 35). The most likely reason for the increase in the number of nematodes under the cool temperature regime from day 2| to day 42 is the slow rate of egg development md hatch at the cooler terrperature. At the warmer terrperature, the eggs developed more quickly, md by day 42 M. Lam had either moved into the root system or died. When observing the stained root system to determine the number of M. M within the roots, 0 significmt difference is again seen early at day 2| (Fig. 36). No significmt differences were detected by day 42 among the inoculum levels md at temperature regimes. 4.2 Solanum tuberosum 4.2.l Pathogen icity of M. hapla to §_. tuberosum roots md tubers M. hgpla had littleinfluence on the general ontogeny of §_. tuberosum; however, it had a major impact on tuber quality (Plate 3). The only significant 76 Table 3. Influence of Meloidogyne hapla and two soil temperature regimes on the taproot quality of Daucus carota (cv Gold Pac) recorded for two harvest dates. Taproot Quality1 Treatment Day 21 Day 42 Nematode-free soil 9-18°c 1.3a2 1.3a 18-25°c 1.0a ' 1.0a Meloidggyne hapla infested soil 9-18°c 1.5a 3.0b 18-2500 3.0b 3.0b 1Taproot quality: 1 represents marketable, 2 represents processing quality and 3 represents nonemarketable. 2Column means followed by the same letter are not significantly dif- ferent (P = 0.05) according to the Student-Newman-Keuls Multiple Range Test. ' 6 4 l 4 I 2 MEAN NO. OF GALLS ON TAPROOT l l 77 Daucus carota Nematode free 9-18‘c Nematode free 18-25'c M. Hapla 9-18 c // M. Hapla 18-25‘c / / / / / 4P 4 0 21 42 DRYS Figure 33. Influence of Meloidogyne hapla and two soil temperature regimes on the number of galls on the taproot of Daucus carota (cv Gold Pac). 78 an lhmucus carota d ! Nematode free 9-18'c P I m Nematode free 18—25'c ’1 19.: ' o M. Hapla 9-18‘c ,’ ///‘ '5 ‘ . M. Hapla 18-25'c / O I c: ’/// / 3‘" " l=' N / " I :5 . ’/// ‘/ a: / uJ I a. I m- I o-e I I 3 / , I (3 . / 1E l/’ ’ C) ‘/ d 0" / [I 25‘" I I I / , 6% 4 / 2 / / I I IDq / [I I I / " I ,I I A “7 o 21 42 DRYS Figure 34. Influence of Meloidogyne hapla and two soil temperature regimes on the number of galls per lateral root of Daucus carota (cv Gold Pac). N i E! o- 0 N A =1 O (I) O 0 m—I o eu- O \ U) hJ 1 E3 E 11.! O- z 0'- L1. 0 O- :4 Z 3 2 .. 79 lkuucus oaroflz Nematode free 9-18°c Nematode free 18-25% M. Hapla 9-18’c M. Hapla 18-25'c 5 \ \ \\ \ Figure 35. 4' 1| 21 42 oars Influence of Meloidogyne ha la and two soil temperature regimes on the num er of M. ha la per l00 cm3 of soil on Daucus carota (cv Gold Pac). MEAN NO. OF NEMATODES—ROOT SYSTEM 160 J 120 l d 80 Daucus carota I! Nematode free 9-18°c In Nematode free 18-25°c 0 M. Hapla 9-18’c 1 A M. Hapla 18-25°c 0 fix I / I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I ”—0”"—6 OO# F 1- 21 42 DRYS Figure 36. Influence of Meloidogyne hapla and two soil temperature regImes on the number of M. hapla per root system of Daucus carota (cv Gold Pac). Plate 3. 81 Influence of W M on the ontogeny of Solanum tuberosum (cv Norchip). Start top row, left to right: I) A healthy md infected §_. tuberosum root system showing the reduced feeder root system and reduced tuber production caused by M. h_c_:p_l_g_. 2) Close-up showing hairy root system, minimal root galling, mature M. M females md large egg sacs. The heavy infestation of the roots shows §. tuberosum is a good host. These symptoms closely match the new description for M. chitwoodi (29, 69). 3) §. tuberosum tuber expressing only a slight amount of lenticel swelling and cracking due to M. h_aglg. 4) _S_. tuberosum tuber expressing extreme lenticel proliferation and cracking due to M. M infection. 5) Each group of three tubers represents the tubers produced by individual §. tuberosum plants. The plants infected with M. Mam produced tubers that were also infected cnd more susceptible to fungal and bacterial pathogens. 6) Cross section through 01 infected tuber showing stained M. h_agl£ female md developing eggs. 82 '0. DAY. A'TII PLANTING .TIRILI INFICTID lmlc 1 :05 DAYS AFTER PLANTING STERILE all ‘ a O 0 a0. "9 flu a INFECTED . § § 83 decrease (P=0.05) in shoot fresh weight caused by M. M was recorded at degree day 775. Root system ontogeny was not significantly retarded by M. M. There were no significmt differences in the total number of tubers produced when M. “_OPE was present (Fig. 37). Tuber fresh weight was not significantly influenced by M. M throughout the growing period; however, the average tuber weight was significantly retarded by M. M (P=0.0S) at 875 degree-days (Figs. 37 & 38). Tuber quality was significantly (P=0.05) lower in the presence than in the absence of M. M (Table 4). M. M also caused a significant (P=0.0l) amount of root galling (Table 4). M. Maglg was observed in all stained cross sections of tubers grown in the presence of M. Lam. Significant (P=0.05) differences were observed in the number of second- stage juveniles per lOO cm3 of soil, and were present from degree-day 875 to 1225 (Fig. 39). Significant (P=0.0l) differences in the number of second-stage juveniles and eggs per gram of root were noted throughout the harvest period (Fig. 39). As the number of eggs decreased, the second-stage juveniles in the soil showed m increase. 4.3 Apium graveolens and Allium cepa 4.3.l Early-season ontogeny of A. graveolens and A. c_em infected with M- male The number of true leaves of A. graveolens or A. c_em' were not significantly (P=0.0S) affected by increasing population densities of M. M during the first 35 days of growth and development. The fresh weight of the entire plants of A. graveolens or A. c_efl also showed no significant (P=0.05) 4.5 MEAN NUMBER OF TUBERS/PLANT Solanum tub erosum cv Norchip (:1 Control A M. Hapk: 675 Figure 37. l ' I ' I fl I ‘ I t‘1 775 875 975 107s 117s 127s SOIL DEGREE DHYS RT HRRVEST Influence of Meloido ne ha la on the number of tubers per plant of So anum tuberosum (cv Norchip). 85 D ‘3‘ Solanum tuberosum cv Norchip 9’: m / ~N~“~a '— 25 l E 3: EE‘ U) LIJ if a: 35’ a _l g— . j... z o I In Control 6 e- I :5 " / ‘5 NL liapfla I . I / I .8.‘ I, I I 1 O 1 . "”675 ' 7115 1 8375 9’75 1575' 1175 I 11275 SOIL DEGREE DRYS RT HHRVEST Figure 38. Influence of Meloidogyne hgpla on the tuber fresh weight of Solanum tuberosum (cv Norchip). 86 Table 4. Influence of Meloidogyne hapla on the tuber quality and degree of root galling of Solanum tuberosum (cv Norchip), recorded for four harvest dates. Category Soil Degree Days at Harvest (Base 43) Infestation 771 883 1034 1232 Tuber Quality; Control 1.0a2 l.2a 1.0a 1.2a M. hapla 1.8a 4.2b 4.6b 6.0b Root Galling3 Control , 1.0a 1.23 1.0a 1.03 M. hapla 5.0b 4.6b 4.4b 5.2b 1Tuber quality: range 1 to 6, one designated a perfect tuber skin qua- lity and six designated 40—50% of the tuber expressed symptoms. 2Column means followed by the same letter are not significantly different (P - 0.05) according to the Student-Newman-Keuls Multiple Range Test. 3Root galling: range 1 to 6, one designated gall-free root system and six designated 91-100Z galled root system. 87 " Solanum tuberosu l e I cv Norah/p O 5 § ‘i’ ‘2" l >‘ I 0 l 8 l g l s g l x SOIL g. 8 I‘ m Roars - l (D E? ‘ ERSGES 2: l is l :5 l l x» O a is ltx ,2 \\\\:\\‘Q’::’ ‘2’ °s7s 775 875 97s 107s 117s 127s SOIL DEGREE DHYS HT HHRVEST Figure 39. Influence of Meloido ne hapla on of second~stage juveniles and per gram 0 on Soianu the number per i 0 cm 0 t. and e m tubers 88 differences from increasing population densities of M. M during the first 35 days of growth. Significant (P=0.05) differences were observed, however, among the dry weights of the entire plants. At day 2|, A. graveolens exhibited significant (P=0.05) retardation in dry weight associated with all three initial population densities of M. M (Table 5). A. mshowed significant dry weight decreases (P=0.05) at day 35 for the two highest population densities of M. h_aglg (Table 5). M. M had no significant influence on the number of root galls associated with A. graveolens (Table 6). The number of root galls associated with A. c_egg, however, was significmtly (P = 0.05) affected by M. M populations. The only significmt difference in the number of lateral roots was expressed in A. gegg at day 35. The estimated soil population of second-stage larvae showed significcnt (P=0.05) differences throughout the 35 days for both A. graveolens did A. c_egg (Table 7). This was totally due to residual soil inoculum. ti.3.2. Influence of four population densities of M. M on the ontogeny of i A. g aveolens 01d A. c_efl The fresh weights of both the shoots and roots for seeded A. graveolens exhibited significant (P=0.05) differences due to increased population densities of M. M. When A. graveolens was transplanted as opposed to seeded, no significant response was observed from the M. [11213 interaction. The fresh weight of the shoots, roots md bulb of A. 9929 were not significantly affected by M. “_QPE after IOS days of growth (Table 8). Dry weight of shoots and roots for both seeded md transplanted A. graveolens showed significant changes in weight due to the increased population densities of M. Lam (Table 9). Dry weights of A. c_e_gg showed no significant 89 Table 5. Influence of Meloidogyne hapla at four population densities on the dry weight of entire plants ongpi m graveolens and Allium cepg, recorded for five harvest dates. Initial Nematode Mean Dry Weight of Entire Plants (mg) Population (eggs/pot) Day 7 Day 14 Day 21 Day 28 Day 35 Apium graveolens 1 0.5 mg 0.9 mg 2.6 mg 0.5 mg 4.1 mg 50 0.4 mg 0.7 mg 1.4 mg 0.7 mg 1.7 mg 500 0.5 mg 0.7 mg 0.8 mg 0.4 mg 5.0 mg 5000 0.4 mg 0.6 mg 0.4 mg 0.4 mg 1.8 mg Allium cepa 0 3.9 mg 3.9 mg 7.4 mg 16.2 mg 28.6 mg 50 4.2 mg 4.3 mg 7.1 mg 11.4 mg 30.4 mg 500 4.1 mg 3.0 mg 7.8 mg 13.4 mg 14.3 mg 5000 3.9 mg 3.2 mg 5.5 mg 11.6 mg 13.0 mg 1Column means followed by the same letter are not significantly dif- ferent (P=0.0S) according to the Student-Newman-Keuls Multiple Range Test. 90 Table 6. Influence of Meloidogyne hapla at four population densities on the number of root galls on Apiumigraveolens and Allium cepa, recorded for five harvest dates. Initial Nematode 'Mean Number of Root Galls Population (eggS/POt) Day 7 Day 14 Day 21 Day 28 Day 35 Apium‘graveolens 0.0al 0.0a 0.0a 0.0a 0.0a 50 0.0a 0.0a 0.2a 0.4a 1.6a 500 0.0a 0.0a 1.4a 0.2a 9.4a 5000 0.0a 0.0a 0.4a 0.4a 8.4a Allium cepa 0 0.0a 0.0a 0.0a 0.0a 0.0a 50 0.0a 0.0a 0.2a 0.2a 1.0a 500 0.0a 0.0a 1.6a 11.8b ll.4b 5000 0.0a 0.0a 5.8b 15.8b 40.2c 1Column means followed by the same letter are not significantly dif- ferent (P=0.05) according to the Student-Newman—Keuls Multiple Range Test. 91 Table 7. Influence of Meloidogyne hapla at four population densities on the soil population of second-stage larvae related to Apium graveolens and Allium cepa, recorded for five harvest dates. Initial Nematode Mban Number of Nematodes/100 cc of Soil Population (eggS/pot) Day 7 Day 14 Day 21 Day 28 Day 35 Apium‘graveolens o 0.0a1 0.03 0.03 0.03 0.03 50 0.0a 0.03 0.03 0.03 0.03 500 0.03 0.03 0.03 ' 0.23 0.6a 5000 20.8b 14.4b 15.2b 7.6b 6.6b Allium cepa 0 0.03 0.03 0.03 0.03 0.03 50 0.03 0.83 0.03 0.83 0.83 500 0.03 4.83 0.43 1.23 2.43 5000 18.4b 14.4b 26.4b 15.2b 17.6b 1Column means followed by the same letter are not significantly dif- ferent (P-0.05) according to the Student-Newman—Keuls Multiple Range Test. 92 Table 8. Influence of Meloidogyne hapla at four population densities on the fresh weight measurements of Apium‘graveolens and Allium ggpa, recorded after 105 days of growth. Initial Nematode Pepulation (eggs/pot) Mean Fresh Weight in Grams Shoots Roots Bulbs Apium_graveolens (seeded) 0 67.331 59.63 --- 50 61.93 49.53 --- 500 54.63b 46.63 -- 4000 42.0b 28.5b --- _Apium‘graveolens (transplants) 164.93 108.83 --- 50 170.53 148.93 --- 500 161.63 155.93 ~-- 4000 168.73 156.13 --- Allium cepa 0 19.33 9.93 17.63 50 20.13 9.83 14.93 500 14.73 7.03 5.13 4000 15.93 8.53 7.13 1Column'means followed by the same letter are not significantly dif- ferent (P80.05) according to the Student-Newman-Keuls Multiple Range Test. 93 Table 9. Influence of Meloidogyge hapla at four population densities on the dry weight measurements of Apium graveolens and A111- gg.cepa, recorded after 105 days of growth. Initial Nematode Mean Dry Weight in Grams Population (eggs/pot) Shoots Roots Bulbs Apium'graveolens (seeded) Apium graveolens (transplants) 0 27.93 14.53 -- 50 26.43 19.73b -- 500 26.63 20.83b -- 4000 25.53 24.2b -- Allium cepa 0 1.83 0.523 1.43 50 1.83 0.503 1.23 500 1.33 0.343 0.43 4000 1.43 0.443 0.73 1Column means followed by the same letter are not significantly dif- ferent (P-0.05) according to the Student-Newman-Keuls Multiple Range Test. 94 3of influence from M. h_qpic_1_. The final M. M population densities per IOO cm soil per l.0 or 5.0 g roots showed significant increases over the nematode-free treatment when both A. graveolens and A. m were seeded (Table IO). M. Mam populations increased significantly on transplanted A. g aveolens. Root galls caused by M. hgglg resulted from all population densities on the seeded A. graveolens, the highest two densities with the transplanted A. graveolens, did the highest population density of M. Mam associated with A. m (TdJle l I). M. M had a detrimental impact on the marketability of both A. graveolens did A. 93m. The impact was less on transplanted thm on seeded A. graveolens. Only the highest population density had an influence on the marketability of A. cgpa. 95 Table 10. Influence of Meloidogyge hapla at four papulation densities on the observed nematode population densities in Apium graveolens and Allium ggpa, recorded after 105 days of growth. Initial Nematode Population (eggs/pot) Mean Number of Nematodes Per 100cc of Soil Roots (5g) Apium‘graveolens (seeded) o 0.0.:1 0.03 50 0.03 0.83 500 0.83 3.23b 4000 4.8b 6.4b Apium graveolens (transplants) ‘ (5 grams) 0 0.03 0.03 50 0.53 2.03 500 5.53 167.0b 4000 12.0b 143.5b Allium cepa (1 gram) 0 0.03 0.03 50 0.63 2.33 500 1.13 5.53 4000 6.0b 8.3a 1Column means followed by the same letter are not significantly dif- ferent (P-0.05) according to the Student-Newman-Keuls Multiple Range Test. 96 Table 11. Influence of Meloidogyne hapla at four population densities on quality characteristics of Apium'ggaveolens and Allium cepa, recorded after 105 days of growth. Initial Nematode Marketability1 Gall2 Bulb Diameter Population (eggs/pot) Index Index (cm.) Apium.graveolens (seeded) 3 0 1.03 1.03 -- 50 1.03 1.8b -- 500 2.8b 4.2c -- 4000 3.0b 5.0d -- Apium'graveolens (transplants) 0 1.03 1.13 -- 50 1.13 3.43 -- 500 1.53b 4.9b -- 4000 2.0b 5.1b -- Allium cepa 0 1.03 1.03 2373 50 1.43 1.13 2.43 500 1.53 1.43 1.73 4000 2.1b 3.0b 1.63 lMarketability: 1 represents marketable, 2 represents processing quality and 3 represents non-marketable. 2Root gall index: range 1 to 6, one designated gall-free root system and six designated 91—1002 galled root system. 3Column means followed by the same letter are not significantly differ- ent (P = 0.05) according to the Student-Newman-Keuls Multiple Range Test. 5. DISCUSSION Information from these host-parasite relationship studies of M. M and selected vegetable crops grown in orgmic soils is of significance for the design of future integrated pest mmagement (IPM) programs, and identification of research priorities. Although it was demonstrated that M. Lam cm function as a pathogen of Q. M, S. tuberosum, A. graveolens and A. c_e‘fi, areas such as cultivar tolerance, crop rotation md time of planting were demonstrated to be of potential value as tactics for lPM strategies. The quality of below-ground parts of plants of economic significmce suffered greater losses in the presence of M. Lam than crops with shoot systems of economic value. Each vegetable crop studied is discussed in relation to the results of the host-parasite relation- ship studies and recommendations for integrated nematode mmagement. The discussion is concluded with crap rotation recommendations for the four vege- table crops evaluated in these studies. 5.I Daucus carota M. 10ng had a major detrimental influence on the early ontogeny of cv Gold Pac. The impact resulted in plant mortality, and not enough plants survived to allow cv Gold Pac to be harvested throughout the entire experimental period. Cv Spartm Premium was more tolerant of M. M than cv Gold Pac; however, M. Egalg was able to reproduce on cv Spmtan Premium. The nematode, however, did not retard growth of the shoot or root systems as much as infection of cv Gold Pac. Shoot system growth was stimulated by M. _hgpM between day 7 did day 2|. Both cultivars produced a better quality tcproot when grown in the absence of M. hapla for at least the first 28 days after plmting. lnoculations 97 98 with M. h_aLIg at day 2| and day 28 appeared to affect the weight of the taproot more thm inoculations from day 7 to day 2|. The same population densities of M. M resulted in similar galling of both cultivars. Both cultivars required at least 56 days under experimental conditions to complete one life cycle of M. M. Second-stage juveniles were recovered from soil after 56 days, whereas only 49-56 days are required for this increase in the root system. Population densities of M. M increased faster on cv Gold Pac than on cv Spartan Premium. To reduce damage to carrot caused by M. _hgglg, it would be preferable to plmt seeds in cool rather thm in warm soil. The effect of M. h_a£l9_ on growth is more pronounced at warmer temperatures due to the more rapid growth of Q. 9221—9“ Under a cooler temperature regime, M. M had a less significant impact on the physiological growth characteristics of Q. Lung. It would be also preferable to use a more tolerant cultivar such as Spartan Premium. Reducing soil populations of M. h_ang can be accomplished through crop rotations md chemical control with fumigants or nan-fumigant nematicides. 5.2 Solanum tuberosum The experimental population of M. M reproduced very well on _S_. tuberosum. The nematode invaded both the root system and tubers. The presence of M. h_a_ng resulted in a decrease in tuber quality and weight. Infestation by M. M resulted in growth responses that made tubers less marketable. Root galling was not noted early in the experimental growth period, and very little hyperplasia was associated with the infection by M. M. Once M. hapla entered the plant, it was able to reproduce rapidly and resulted in high 99 population densities. Evidence presented in Plate 3 indicates it is possible that the experimental population was M. chitwoodii (Columbia root-knot nematode) (29, 69) did not M. M. To reduce S. tuberosum damage caused by M. Lam, it is preferable to use certified seed pieces free of nematodes. When possible, use the most M. M- tolerant cultivar available. The most common population reduction practice is the use of non-fumigant nematicides, but proper crop rotations can be beneficial. With extremely high soil populations of M. Maggi, the use of a soil fumigation would be incorporated into the integrated management program. 5.3 Apium graveolens md Allium cepa M. [ERIE-induced differences in the growth characteristics of A. gravealens and A. c_em were not expected during the first two harvest dates (day 7 and day l4) because of the time required for seed germination md hatching of M. M eggs. High initial population densities of M. [gig (5,000 eggs/pot) restricted the shoot system growth of A. graveolens, but not A. gem. This finding agrees with Brady (6). A. graveolens was a good host for M. h_apl_g reproduction, md growth retardation resulted from infection by this nematode. The lack of an influence on shoot growth by A. c_egg agrees with the findings of lzatullaeva (43). A. 29% 3of was tolerant to M. h_apM with population densities under 500 larvae/I00 cm soil. Both A. graveolens and A. c_epg require long growing seasons to reach market maturity. A. graveolens requires from 56 to 98 days for transplant production, and m additional 85 to I30 days of growth for market quality plants. A. c_eg requires 85 to I20 days from seeding to maturity (74). This research 100 examined only the first l5 to 30% of these growth periods. The number of root galls formed on A. graveolens was greater then on A. (339. As the population density of M. M on A. gm increased, there was a consistent increase in the number of root galls per plmt. A noticeable problem of this evaluation was that root galls were not as pronounced in size on A. Egg as on A. graveolens. Expression of the "hairy root" symptom was not noticed for A. graveolens during the first 35 days of growth. There was no indication that either host was adequate for M. h_ang to complete an entire life cycle in the 35 days. M. h_aglg had a detrimental influence on the ontogeny of A. graveolens (grown from seed) to be used for transplants or on transplants planted in M. mag-infested soil and grown to market size and quality, did on seeded A. SEE grown to market quality. A harvest date of I05 days was chosen because it is close to the growing season length needed by the crops under normal field conditions. The most noticeable impact of M. M was on the growth of healthy A. graveolens transplants from seed. It was observed that a nematode- free growing environment is more important to seeded A. graveolens than to transplanted A. raveolens. This finding agrees with those published by the Florida Agricultural Experiment Station (7) and emphasizes the need for nema- tode-free transplmts in the Michigan Celery Industry. Nematode-free trans- plmts were able to sustain root damage by forming tertiary root systems (hairy root symptom) which help to sustain normal shoot growth. The fresh weight of shoots, roots and bulbs of A. c_ea were not sigiificant- Iy affected by populations of M. M. M. M increased root growth with no decrease in top growth when nematode-free transplants are grown to market quality. At the highest initial M. hapla population, all three plants (celery from 101 seed, celery transplants md onions from seed) showed significant increases in soil populations of second-stage larvae. Root tissue from both seeded and transplanted A. graveolens showed significant increases in the population of M. M. A. 9229 did not show a significant increase in the root population of M. M. When one randomly selected feeder root was stained, significant increases of M. QgpLa were observed for seeded celery, transplanted celery and seeded onions. Larger final populations are expected from increased initial populations because of the large reproductive capacity of M. hgglg. The more reproducing females present initially allows for earlier logarithmic population growth md larger final populations. The growing of muck vegetables often uses the crop rotation of carrots to celery to onions did back to carrots. Onion production the year before carrots has been a recommendation to reduce field populations of M. M. The same soil population of M. M cm be reduced 50% more by A. c_em thm if A. g aveolens was produced. Another important factor for the determin- ation of A. c_em as a host plmt is in its available root mass. A. c_epgonly has I / II the root fresh weight and only I/28 the root dry weight of transplanted A. raveolens. This reduced root mass for A. gm means there are less penetration points or invasion sites for M. h_a_p_lg_ to attack in the A. w root system. With m initial population of 4000 eggs/pot, one gram of A. graveolens roots produced an average of 29 second-stage juveniles of M. M. Under the same conditions only 8 second-stage juveniles were produced in one gram of A. c_epg roots. At harvest A. graveolens has 63 times more M. Maqu in an average root system (4524 nematodes/plant) than that found in 01 average A. (329 root system (7| nematodes/plant). A. cgpa‘s reduction of field populations of M. 102 M is derived from the reduced root mass md lowered reproductive capacity of M. h_aLIg using A. 993; as a food source. As few as I2.5 M. M eggs/I00 cm3 of soil at planting can cause significant damage to seeded A. graveolens. A. graveolens has a large root mass and is a good host for M. DM° A. 3133 is a marginal host for M. m did is cqoable of reducing field populations of M. M by as much as 98 percent. To reduce A. graveolens damage caused by M. m use of clean, nematode-free transplants is the most important strategy. If growing trans- plants, a sterilized seedbed is important. Proper cultivar selection for both A. graveolens and A. c_efl could help to reduce M. h_apl_a damage. Both crops could use non-fumigmt nematicides in fields with high population densities. Greater economic benefit would be derived from chemical control used on seeded A. raveolens. 5.4 Integrated nematode management for selected muck vegetables There are four main strategy categories which can be used in designing a M. _hgm management program. If M. Epl_a is not yet present in the field, keep it out by using certified seed and good sanitation practices. If M. M is introduced into a production system site, did it is at low levels, early attempts may be used to eradicate the nematode population. Eradication is rarely possible under field conditions, did it should be noted that chemical nematicides cm result in m increased nematode reproductive rate due to loss of natural enemies. If the field is known to have M. h_a_p_lg did its presence is verified by soil samples, there are two strategies left. One is to do, nothing, and the other is to take measures to control the population. The three areas where the system can be 103 manipulated to achieve the desired degree of control,are the crop, the pest, or crop-pest interaction sites. One tactic would be to change planting to either m earlier or later date to achieve a more favorable crop-pest interaction. M. M population densities could be reduced chemically by use of soil fumigmts and/or non-fumigmt nematicides. Use of proper crop rotation sequences could also be used. A good example of this strategy is to plant A. c_egg but not S. tuberosum or A. graveolens the year prior to Q. g:r_Ot_a_ (Table l2). The best way to alter the crop would be by the use of a tolerant cultivar or, in the case of S. tuberosum did A. graveolens, certified seeds or transplants. 104 Table 12. Data summary of various characteristics which can be used to determine whether Daucus carota, Solanum tuberosum, Apium graveolens, or Allium cepa fit into 3 crop rotation program designed to reduce Meloidogyne hapla papulations. Characteristic " ---»~—-~---- --- ~-~~~v»~—--~~-—---------"-"“- or Q. carota _S_. tuberosmn A. graveolens A. 5.3.23 Quality v~~~~ - ~-— - -w~-- -—-~~~~ ~ «-—~~ M Crop loss potential Very high1 Moderate High Low Damage threshold Very low Variable Low High Host status Excellent Fair Excellent Poor Dissemination risk None High High None Pest risk on crap Very high Low (moderate) High Low Rotation crOp Poor Poor Very poor Good 1The above summaries and classifications were derived from research results and literature reviews. 6. LITERATLRE CITED Adams, M.J. I975. Potato tuber lenticels: susceptibility to infection by Erwin ia carotovora var. atros tica md Phytophthora infestans. Annals of Applied Biology 79:275-82. Anderson, J.L. aid G.D. Griffin. I972. Interaction of DCPA chd trifluralin with seedling infection by root-knot nematode. (abstract) Horticultural Abstracts 45:3944. Artschwager, E. I924. Studies on the potato tuber. Journal of Agricultural Research 27:809-35. Berbec E. I976. Meloid ne hapla Chitwood on some carrot cultivars. I-Iodowla Roslin Kline! fLyzoe' ja i Nasiennictwo 20:8l-96. Bergeson, G.B. I959. The influence of terrperature on the survival of some species of the genus MeloiMne in the absence of a host. Nematologica 4:344-54. Bird, A.F. I959. Development of the root-knot nematodes Meloidogyne javmica (Treub) md Meloidggzne hapla Chitwood in the tomato. Nematologica 4:3I-42. Bird A.F. I959. The attractiveness of roots to the plant parasitic nematodes Meloiflme javmica md M. M. Nematologica 4:322- 335. Bird, A.F. I974. Plant response to root-knot nematode. Annual Review of Phytopathology I2:69-85. Bird, A.F. md W.R. Wallace. I965. The influence of temperature on Meloidogyne Maid M. javmica. Nematologica ll:58I-89. Bird, G.W. |97l. Influence of incubation solution on the rate of recovery of Pratylenchus brachyurus from cotton roots. J. Nematology 3:378- 85. Bird, G.W. I980. Nemtology—Status and Prospects: the role of gematology in integrated pest management. J. Nematology I2:I70- 6. Brodie, B.B. and R.L. Plaisted. I976. Resistance to root- knot nematodes in Solanum tuberosum ssp. andigena. (abstract) J. Nematology 8:280. 105 20. 2|. 22. 23. 24. 25. 106 Brody, J.K., Jr. I972. A study of a Michigan isolate of Meloidogyne hapla. Masters Thesis. Dept. of Entomology, _Michigan State University, East Lansing. Brzeski, M.W. I974. The reaction of carrot cultivars to Meloidogyne h_ang Chitw. infestation. Zeszyty Problemowe Postepow Nauk Roln iczych No. I 54: I 73—8 I. Brzeski, M.W. md Z. Bojda. I974. The northern root-knot nematode (Meloid ne hgpla Chitw.) on carrot-pathogenicity and control. Zeszyty ro Iemowe Postepow Nauk Rolniczych I54:I59-72. Canada Department of Agriculture. I974. Research Branch Report I973. Ottawa, Ontario, Cmada. 366 pp. Chase, R.W. I976. Selecting Potato Varieties in Michigan. MSU Ag. Facts. Extension Bulletin E-935. pr. Chase, R.W. aid N.R. Thompson. I967. Potato Production in Michigcn. Michigm State University Cooperative Extension Service. Extension Bulletin 546. I4 pp. Chemagro Agricultural Division. I975. Pest Mmagement Guide for Potatoes. Printed in U.S.A. 2I pp. Cherekova, D.S. I965. Nematodes on tomato md potato in the Odessa region, Ukrainian SSR. In Raboty po parazitofaune yugo-zapada SSSR. pp. l5I-52. , Chitwood, B.G. I949. Root-knot nematode—Part l. A revision of the genus Meloid_ggzne Goeldi I887. Proceedings of the Helminthological Society of Washington I6:90-I04. Chylinska, K.M. md J.S. Knypl. I975. Decreased phenylalanine ammonia- Iyase and ribonuclease activity in side roots of carrot infested with the northern root-knot nematode. Nematologica 2|:l29-33. Commonwealth Institute of Helminthology. I974. Descriptions of plant paragitic nematodes. William Clowes & Sons, Ltd. London. Set 3, No. I. Daulton, R.A.C. and C.J. NJsbaum. I96I. The effect of soil temperature on the survival of the root-knot nematodes Meloidogyne javanica and M. hapla. Nematologica 6:280-94. Davide, R.G. and A.C. Triantaphyllou. I967. Influence of the environment on development and sex differentiation of root-knot nematodes. I. Effect of infection density, age of the host plant and soil temperature. Nematologica I 3: l02- l0. 26. 27. 28. 29. 30. 3|. 32. 33. 34. 35. 36. 37. 38. 107 Davide, R.G. and A.C. Triantaphyllou. I967. Influence of the environment on development and sex differentiation of root-knot nematodes. II.‘ Effect of host nutrition. Nematologica l3:I I l-I7. Endo, B.Y. I975. Pathogenesis of nematode-infected plants. Annual Review of Phytopathology l3:2l3-38. Ferris, H. I978. Nematode Economic Thresholds: derivation, requirements and theoretical considerations. J. Nematology I0:34l-50. Golden, A.M., J.H. O'Bcnnon, G.S. Santa and A.M. Finley. I980. Description and SEM observations of Meloidogyne chitwoodi: N.S.P. (Meloidogynidae), a root-knot nematode on potato in the Pacific Northwest. J. Nematology l2:3I9-27. Goodey, T. I932. On the nomenclature of the root-gall nematodes. J. Helminth. I0(I):2I-28. Great Lakes Chemical Corporation. The hmdbook of agricultural fumigation. I9 pp. Griffin, G.D. md E.C. Jorgenson. I969. Pathogenicity of the Northern Root-knot nematode (Meloi ne h la) to potato. Proceedings of the Helminthological Iety o as ington 36:88-92. Gritsenko, V.P. I975. The species composition md population dynamics of nematodes on potatoes and the effect of different crop rotations. In Gel'mintologicheskie issledovaniya v Kirgizii. pp. l23-36. Guzman, V.L., H.W. Burdine, E.D. Harris, Jr., J.R. Orsenigo, R.K. Showalter, P.L. Thayer, J.A. Winchester, E.A. Wolf, R.D. Berger, W.G. Genung md T.A. Zitter. I973. Celery production on organic soils in South Florida. Bulletin, Florida Ag. Exp. Stations, Gainesville No. 757, 79 pp. Haynes, D.L. aid contributors. I980. CO Induced climatic change md its effect on plant protection. The national program on carbon dioxide, environment and society. Dept. of Entomology, Michigm State University, East Lansing, Michigan. Hendricks, E.K., M.W. Brzeski and Z. Bojda. I97 I. Studies on Meloidggyne hgpla Chitw. (Nematoda Tylenchido): annual number of generations on carrot. Bull. de I'Academie Polonaise des Sciences. Serie des Sciences Biologigues I9:733-35. Homeyer, B. I975. Curaterr, a broad spectrum root-systemic insecticide and nematicide. Pflanzenschutz-Nachrichten Bayer 28:3-54. Hoyman, W.G. I974. Searching for resistance to Meloidggzne hapla. (abstract) American Potato Journal 5|:278. 39. 40. 4|. 42. 43. 45. 47. 49. 50. SI. 108 Hoyman, W.G. I974. Reaction of Solanum tuberosum md Solanum species to Meloidggme hgpla. American Potato Journal 5|:28 - Huang, J.S. I976. Possible mechanisms involved in host specificity. In International Meloidogyne Project. Proceedings of the research planning conference on root-knot nematodes, Meloid ne spp., |2-l6 Jarisgaréyé I976, Raleigh, N.C., USA. North Carolina tat te University. p. - . Hussey, R.S. and KR. Barker. I973. A comparison of methods of collecting inocula of Meloid ne spp. including a new technique. Plant Disease Reporter 57 "535-28. ’ Inoue, H. I973. Increase in numbers of root—knot nematode aid reduction in yield caused by the successive cropping of spring and autumn potatoes. (abstract) In I7th Annual Meeting of the Japmese Society of Applied Entomology and Zoology. p. I35. lzatullaeva, R.l. I976. The determination of the critical threshold of the pathogenicity of Meloid ne hapla Chitw., I949. Vestnik Sel'skokhozyaistvennoi Nauki azakhstana. No. l:l IO-I I. Janos, K.M. I976. Activity of indonI-3-acetic acid oxidase md peroxidase in roots of carrot infested with Meloid_ogyne hgpla Chitw. Acta Agrobotanica 29: I07-I7. Jatala, P. md P. R. Rowe. I976. Reaction of 62 tuber-bearing _S_o__lanum species to the root-knot nematode, Meloidggme ncgggita ac__rita. (abstract) J. Nematology 8. 29.0 Jenkins, W. R. I964. A rapid centrifugal-flotation technique for separating nematodes from soil. Plant Dis. Rep. 48:692. Jenkins, W.R. md D.P. Taylor. I967. Plant Nematology. Ch. 9:I00-I2 pp. Reinhold Publishing Corporation, New York. 270 pp. Karimova, M.M. I973. Nematode fauna of carrots md onion. Uzbekiston Biologiya Zhurnali No. I:54-55. Knott, J.E. I962. Handbook for Vegetable Growers. Wiley Publishing Co., New York. 245 pp. Knypl, J. S. md K. M. Jonas. I975. Synthesis of RNA and protein, with ribonuclease activity, in carrot roots infested with Meloidggzne hgela Chitw. Physiolog. Plant Pathol. 7: 2I3- 20. Laughlin, C.W. The Hidden Enemy: Nematodes did their control. Extension Bull. E-70I. Michigan State University. l4 pp. 52. 53. 54. 55. 56. 57. 58. 59. 60. 6|. 62. 63. 64. 109 Mai, W.F. I976. Influence of different agricultural systems on control strategies for root-knot. In International Meloidogyne Pro'ect. Proceedings of the research planning conference on root not nematodes Meloid e spp. I2-I6 January I976 Raleigh NC. USA. North Carolina State University. pp. 94-I04. ’ ’ ’ Mmkau, R. I980. Biocontrol: fungi as nematode control agents. J. Nematology I2:244—52. Martin, G.C. md A.M. Armstrong. I975. Potatoes in Rhodesia. Part 3. Nematode pests of potatoes. Technical Bulletin, Rhodesia Agricultural Journal No. I|:27-3|. May, J.N. I888. Club roots. Am. Florist 3:396. Michigm Agricultural Statistics, I976 Annual Summary. Michigan Crop Reporting Service, Lansing, Michigan. June I977. Michigan Agricultural Statistics, I979 Annual Summary. Michigm Crop Reporting Service, Lansing, Michigan. June I980. Michigm Crop Reporting Service. I978. Vegetables. Michigm Dept. of Agriculture. Lansing, Michigan. Released January II, I978. 2 pp. Michigm Potato Industry Commission. What's a Michigan potato? Michigan Potato Industry News. Vol. I6:(9) special edition. Morley, S. md M. Beckman. I972. Consumer Preferences md Opinions on Carrots. Extension Bulletin E—748. Marketing Series. Michigan State University. 8 pp. Mukhametshin, M.S. Nematodes on potato in Bashkiriya (USSR). Materialy Naucgigykh7 I7has no Adv nouauuvau unenlac have: new; « e o o o = 2 o. .- ooo.oo~ ooc.ks~ coo.ks~ ooo.ecH o a. c. : coo.oc~ ccc.ke~ coo.kq~ ooc o c onn.e ooo.- ook.- oak.“ ccc.mn coo.~cu ooo.~mu can.oo o acxauouuao uo Macias o c ooc.oo~ oco.se~ ooc.~e~ coo.oo~ c .oou coo.oo~ ooc.scu coo.neu coo.co~ occ.oo~ oco.nqn coo.sen 609.06“ assauuxuu: nuance gaseous: o can.en cca.~e egos» usauuoxsa: sauce oco.oe cca.os cc~.oe ooo.~s egos» sauce coo.n cc~.n~ cca.- ode.» coo.n eea.n~ e°~.ofi oc¢.e eco.n ooc.o~ can.a~ one.» cka.n oe~.o~ ccc.oH ook.k a_oar a; \ as a.~n c.5c n.c~ n.o~ ans e.nn n.ec ~.ns A.Ma NNH s.nn a.eo ~.ek o.nm «l «as a.sa «.55 0.65 c.- o.o a.nn o.on o.aq o.oe n.5n o.no N.Sk o.on “.mo a.- o.- o- as. ~n. on. no. «a. no. -.~ nu.“ as." no.~ no.~ o~.~ cc.“ ~a.~ o~.~ oe.~ on so. Ho. No. No. No. no. no. so. co. co. we. we. no. co. go. so. on So. So . :5. :5. So. «8. 8e. 8e. n8. n8. 3:. «8 . o n8 . 3c . 3c . on o a o o o c o o o c o o c a o a mg .n ..u: sauna goons-h s n a d c n ~ A c n N A c n ~ A unqueoum nouu< use: cawuamsmom uouuao ocu cm ecuuauamam uauuau aauunusno~ youuau ed sauuansmom uauuau O mama. no uuoo~\uual::m uu>ua~ uuaua vacuo- nawuuau no non-3: ¢¢.uo6m ua unwound: a ham u~o>u~ occualoa adduuaw Issuua> ua aouuuqvuun amoua sea uuauuau «a uswuu: sauna .Ha< «Hash 134 Increased initial nematode levels caused a longer time to harvest at 60°F (Table A-2). Total yields were slightly higher than 50°F planting temperature and again show no response to various nematode levels. The higher planting temperature (60°F) resulted in a slight increase in marketable yield for 0 nematodes (2,000 Kg/ha) with a lo day earlier harvest. Initial nematode populations of 50 and l00 produced no marketable yields. Nematode levels in this order are rarely found in muck soils and would probably cause a total loss of a carrot field (Bird I977). An initial level of IO nematodes caused a reduction in marketable yield of |2,500 Kg/ha or 25% which was very close to the results noted previously. Carrot fresh weight by population, versus initial nematode population, and planting temperature of 80°F shows a decrease in carrot weight with increasing initial nematode population (Table A-3). At l20 days, the first population of carrots planted at 80°F yielded 59.7g. with zero nematodes, 52.39. with ID nematodes, 30.79. with 50 nematodes, and l5.89. with l00 nematodes initially. Time from planting to harvesting is |24 days with zero nematodes and l26 days with ID nematodes. With initial populations of 50 and |00 nematodes, it was best to harvest when the carrot weights were low because it was the end of the season. Carrot fresh weight decreased with increasing nematode numbers at a planting temperature of 70°F (Table A-4). Numbers of days necessary to reach a harvestable weight increased with increasing nematode populations. Comparison of lengths of time necessary to harvest carrots between populations planted at 80°F and those planted at 70°F showed more time needed when the planting temperature was 80°F. This is because with an average daily air temperature 135 “AAA .A an: oboe ucAsceAs .. uao>haa ua you auuaauvcm uuonlac have: ocua e o o o o a c o o cao.e eon.~A ceo.nA onn.o coo.ooA coe.nm~ oco.mm~ oco.ooA «Aaouoxsa: : : : : : 8 A. .. 8O . nN SN .6m 8H .06 8m . 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Aoc. woo. woo. moo. moo. coo. mac. coo. woo. woo. mA .m ..u> sebum uoouaah A A A n A A A A A A A A meAucaAe usuu< exam :oAuaAsmom uopuau :oAuaAamom uouuao :OAuaAsmdm uouuau :oAuaAsmom uouuau GOA cm cA o aAAam uo uuocA\uuna=:v ua>haAfwwwua vacuum AaAuACA mo nuneaz ««.uao~ ua maAucaAa a you aAu>oA occuaEuc AaAuAaA nsoAua> ua aeoAuuAcaua vAuA> was muouumu mo uzwAa3 :mauh .ci< uAnay 138 for planting of 80°F, carrots were not planted until day 84 (approximately June 24th) and the model was forced to grow carrots through the month of September when average daily temperatures were dropping. There were no forked carrots with planting temperatures of either 70°F or 80°F. This is because the nematode subroutine set the number of nematodes to zero after 350 soil degree days had been accumulated. With a planting temperature of 80°F, the planting date of June 24th was long after the nematodes had reached zero. With a planting temperature of 70°F, the planting date of May l8th also came after the soil nematodes died md were set to zero. The following table gives the total marketable yield versus nematode population by planting temperature: . —--Carrot Yield kg/ha—-- Nematode Population Planting Temp. 0 IO 50 |00 70°F 52:00 53200 53400 52400 80°F 5 1000 52900 3| IOO l6000 Yields are higher with increasing nematode populations at 70°F and from zero to ten nematodes at 80°F, because the model did not harvest until the second carrot population reached 70 grams. This resulted in the possibility of carrot populations from one run with higher nematodes to have greater weight than carrot populations of a run with fewer nematodes. Yields are high at 70°F, and at 80°F with zero md ten initial nematodes. This result was due to the fact that no carrots were forked because of the death of all soil nematodes. Through the use of the model it is shown that average air temperatures of 70 and 80°F may be unrealistic for planting. Future runs of the model should 139 harvest all populations at a certain day after plantjng rather than when the second population attains 70 grams. This will eliminate increasing yields with increasing numbers of nematodes. It would also be possible to grow the carrot crop under I976 weather conditions. MANAGEMENT STRATEGIES Management strategies which could be employed using the present model include the following: (I) Obtain nematode counts from soil samples before planting. F allow the population dynamics through the season using the program and observe losses in yields which could result from this initial population. This could then indicate whether some control through use of nematicides is neces- say before planting. (2) Observe the fluctuations in nematode populations throughout the season. Vary the planting date to synchronize germination with periods of low populations. Observe losses in yields with different planting dates in order to predict planting dates which give the most economical returns. The present model could, however, be a significantly more effective management tool if a subroutine simulating the economics of the crop production with md without nematode control through the use of nematicides were included. The system could then predict whether control should be employed md if so, which nematicide would give the best economic returns. The program could also be altered to predict yields using simulations for growth of different crops, thus simulating a crop rotation type of control practice. This could then predict which crops would be most economically suitable to be used in a crop rotation control program. SUMMARY The model indicated that carrot yields can be significantly reduced by initial nematode populations in the soil. As the nematode populations increase, carrot yields decrease accordingly, and total crop loss may result. 2nd stage larvae in The subroutine developed to predict the numbers of plant roots displayed some instability, and these numbers appeared to fluctuate from zero to relatively high numbers instantaneously. Attempts to remedy this subroutine will be approached by reexamining (I) the equations used to predict survival, development md reproduction of this nematode md (2) the subroutine which was used to generate the age distribution of various stages of the nematode life cycle. Manetsch (I974) pointed out that instability in models may result from incorrect use of this subroutine. He states that a necessary condition for stable simulation using this subroutine is that the DT selected should be such that: I 2MlN (Di) should be greater than DT md greater than 0 where MIN (DI) is the smallest delay constant in the model, and if for each delay all 01's are equal, then DT should be selected that: 2MIN (DELj/Kj) should be greater than DT and greater than 0 where DELj is the main delay of the jth distributed delay, K] is its order and MIN operator determines the smallest ratio of DEL to K. Manetsch (I974) further states while these equations give 01 upper bound for DT in simulation models employing euler integration, as a practical matter it is necessary to use an appreciably small value of DT in order to reduce the integration errors to acceptable limits, and as a rule of thumb DT should be less than l/4 of the upper limit of the stability bound. The simulation will be 140 141 considered again by dividing the present DT of l into 5 smaller increments so that DT will be 0.2 DT. A Do loop could then be included to simulate development 5 times, in effect simulating with 0 OT of I. This does not imply that biological changes occur with 0.2 of a day. The | day DT is simply divided into smaller time steps to allow for greater stability in using this subroutine. The K values will also be re-examined and changed if necessary. The subroutine required initialization of its delay and storage blocks, and these were initialized to zero. This may have been an incorrect asssumption and will therefore be re-examined. An exponential equation was used to predict carrot yields, and this resulted in larger than normal values with increase in time. This equation will be re- examined md possibly replaced by a logistic equation which would predict crop yields more accurately. REFERENCES Agrios, G. N. I969. Plant Pathology. Academic Press. New York and London. Austin, R. B. I963. A study of the growth and yield of carrots in a long-term manurial experiment. J. Hort. Sci. 46:299-305. Austin, R. B., J. A. Nedler, and G. Berry. I964. The use of a mathematical model for the analysis of manurial and weather effects on the growth of carrots. Annals of Botany. 28: l03—l6l. Bird, G. W., M. Sarette, C. Coley and E. Meister. I975. On-Line pest crop ecosystem simulation for Pratylenchus metrans md Solanum tuberosum. Dept. of Entomology, Michigan State University, East Lansing. (unpubl.) Bird, G. W. I977. Personal Communication. Brody, J. K. Jr. I972. A study of a Michigan isolate of Meloid_ogzne Laglg. Masters Thesis. Dept. of Entomology., Michigan State University, East Lansing. Commonwealth Institute of Helminthology. I975. Descriptions of plant parasitic nematodes. William Clowes and Sons Ltd. London. Ferris H. I976. Development of a computer-simulation model for a plant nematode system. J. Nematol. 8:255-263. Hegarty, T. W. l97l. A relation between field [emergence and laboratory germination in carrots. J. Hort. Sci. 46:299-305. Jones, F. G. W., D. M. Parrot, and G. J. S. Ross. I967. The population genetics of the potato cyst nematode. Heterodera rostochiensis: mathematical models to simulate the effects of growing eel-worm resistmt potatoes bred from Solanum tuberosum ssp. Andigena. Ann. Appl. Biol. 60:l5l-l7 l. 142 143 Klinger, J. I965. On the orientation of plant nematodes and some other soil animals. Nematologica. l l:4- l 8. Manetsch, T. J. and G. L. Park. I974. System analysis and simulation with applications to economic and social systems. Part II. Dept. of Eng. and Sys. Sci., Michigan State University, East Lmsing. McGillivrag, J. H., G. C. Hanna and P. A. Minges. I942. Vitamin, protein, and calcium, iron md caloric yield of vegetables per acre and per manhour. Amer. Soc. Hort. Sci. Proc. 4l:293-297. Nicklow, C. W., R. C. Herner, J. D. Downes and R. E. Lucas. I976. Carrots extension Bull. E-675-G. Michigan State University, East Lansing. Ruesink, W. G. I976. Status of the systems approach to pest management. Ann. Rev. Entomol. 2|:27—44. Slinger, L. I976. Ontogeny of _D_quggs ca_rotg in relation to Meloidggzne M with a preliminary endomycorrhizal study. M. Sc. Thesis. Michigan State University, East Lansing. Tyler, J. I933. Development of the root-knot nematode as affected by temperature. Hilgardia 7:39 l-4 l 5. Whitaker, T. W., A. F. Sherif, W. H. nge, C. W. Nicklow, and J. D. Radewald. I975. USDA, Handb. 375. 37pp. Carrot Production in the United States. Wilson, J. D. I962. Crop rotation md the control of root-knot on muck grown vegetables. Phytopathol. 52:33. Vm Arkel, R. md G. W. Bird. I977. Unpublished data. Vegetable - Fresh Market. I975. Annual summary. USDA, Washington, D. C. June I976. Zadoks, J. C. l97l. Systems analysis and the dynamics of epidemics. Phytopathol. 6|:600-6l0.