5. LIBRAAY MichiganStatc ‘ . Univ-unity my; “minimum!" i'iiii‘ militia THE-9" This is to certify that the thesis entitled Factors Affecting Leaf Scorch and Root Rot Disease of Lilium longiflorum thunb. cv. Ace presented by Carol J. Bornstein has been accepted towards fulfillment of the requirements for M. S . Department of de ee in gr Horticquure . [,7 fifiall/L - «61/174: y-quL/z Major pléfessor/ Date Zt.£3"2/z’¢gt»;:/ «Z [72 C/ J" 0-7 639 OVERDUE FINES ARE 25¢ PER DAY _ PER ITEM remove “ Return to book drop to r record. ‘M v: EEMQV this cimckout from you mean 1 1 4-11ng 31939 »—~ ~.... 5 A 4/ “—.. ‘5o1 FACTORS AFFECTING LEAF SCORCH AND ROOT ROT DISEASE 0F LILIUM LONGIFLORUM THUNB. CV. ACE By Carol J. Bornstein ~A THESIS Submitted to Michigan State University in partial fulfiilment of the requirements for the degree of MASTER OF SCIENCE Department of Horticulture 1978 ABSTRACT FACTORS AFFECTING LEAF SCORCH AND ROOT ROT DISEASE OF LILIUM LONGIFLORUM THUNB. CV. ACE By Carol J. Bornstein Lilies grown in perlite-amended and superphosphate- fertilized media had more scorched leaves than those grown in dicalcium phosphate/Turface. Three day/night temperature re- gimes indicated leaf scorch generally decreased as temperature increased. Soil F content, highest in superphosphate/perlite medium at the lowest temperature, was positively correlated to scorch. Leaf Na and Zn levels were highest in plants grown in perlite- amended and superphosphate-fertilized media, respectively. These nutrients were positively correlated to scorch. Lilies grown in soil-less media were severely scorched; soil-grown control plants had no scorch. Medium and leaf F content correlated positively to scorch, and soil-less media had high media F levels. The soil medium had the highest soluble salts, N, K and Ca levels. Porosity of these media correlated Carol J. Bernstein positively to scorch. Root-rotting fungal infection differed significantly among media. Fresh weights of scales. shoots, stem roots and basal plate plus roots were monitored and showed significant weight changes over time. To Ambyr, Martha, Nancy, Patty and Sally. And to Ned. ii ACKNOWLEDGMENTS I wish to thank the members of my committee, Dr. Ronald Spangler, Dr. Frank Laemmlen, Dr. William Carlson and Dr. Darryl Narncke for their help and guidance; Dr. August De Hertogh for always listening and sharing his knowledge; Dr. Charley Cress, John Wells and especially Miguel Leon for their advice and assistance concerning statistical analysis; Norm Blakely for his technical assistance; Donna Alexander for her coopera- tion in preparing this manuscript; Bob Kelly for his friendship and encouragement; and my parents for their love and support. iii TABLE OF CONTENTS LIST OF TABLES. LIST OF FIGURES I. LITERATURE REVIEW. Introduction . . Forcing Program. Leaf Scorch. . . Planting Medium . . Easter Lily Root Rot Disease Complex Porosity . . II. OBJECTIVES III. MATERIALS AND METHODS. Effect of Media, Fertilizer and Temperature on Leaf Scorch. . . . Effect of Soil- less Media on Lily Growth and Root Rot Disease Development Porosity Determination of Soil- less Media. Measurement of Fungal Growth in Soil- less Media. . . . . . . . . . . . . . IV. RESULTS AND DISCUSSION Effect of Media, Fertilizer and Temperature on Leaf Scorch . . . Effect of Soil- less Media on Lily Growth and Root Rot Disease Development . . Porosity Determination of Soil- less Media. Measurement of Fungal Growth in SoiL less Media. . . . . . . . . . . . . . V. SUMMARY AND CONCLUSIONS. VI. BIBLIOGRAPHY APPENDIX. iv _I_a—aw._a._n \lho Page viii 24 26 27 29 31 33 33 52 65 7O 71 76 84 LIST OF TABLES Table Page 1. Linear correlation coefficients for scorch count and rating in relation to leaf analysis, 'Ace' Easter lily scorch experiment, l978. . . . . . . . 39 2. Effects of temperature and fertilizer/amendment on nutrient content of 'Ace' Easter lily leaves, scorch experiment, l978. . . . . . . . . . . . . . 40 3. Post-scorch experiment soil analysis, l978 . . . . . 4l 4. Linear correlation coefficients for scorch count and rating in relation to soil analysis, 'Ace' Easter lily scorch experiment, 1978. . . . . . . . 42 5. Influence of growing medium on leaf count and scorch count of 'Ace' Easter lily, T977 soil- less media experiment. 53 6. Influence of growing medium on disease and leaf scorch of 'Ace' Easter lily, l978 soil-less media experiment . . . . . . . . . . . 56 7. Linear correlation coefficients for scorch count and rating in relation to soil analysis, 'Ace' Easter lily soil-less media experiment, l978 . . . 58 8. Post-soil-less media experiment soil analysis, l978. 59 9. Linear correlation coefficients for scorch count and rating in relation to leaf analysis, 'Ace' Easter lily soil-less media experiment, 1978 . . . 60 10. Effect of growing medium on nutrient content of 'Ace' Easter lily leaves, soil-less media experiment, l978 ... . . . . . . . . . . . . . . . 61 ll. Percent air porosity of soil-less media. . . . . . . 66 Table Page 12. Linear correlation coefficients for root rot, leaf loss, scorch count and rating in rela- tion to porosity, 'Ace' Easter lily soil-less media experiment, l978 . . . . . . . . . . . . . . 69 Al. Influence of temperature and fertilizer/amendment treatments on leaf scorch (number/plant) of 'Ace' Easter lily, 1978. . . . . . . . . . . . . . . . . 84 A2. Influence of temperature and fertilizer/amendment treatments on scorch rating of 'Ace' Easter lily, l978 . . . . . . . . . . . . . . . . . . . . 85 A3. Influence of temperature and fertilizer/amendment treatments on bud count (number/plant) of 'Ace' Easter lily, l978. . . . . . . . . . . . . . . . . 85 A4. Influence of temperature and fertilizer/amendment treatments on leaf count (number/plant) of 'Ace' Easter lily, l978. . . . . . . . . . . . . . . . . 87 A5. Influence of temperature and fertilizer/amendment treatments on total height (cm) of 'Ace' Easter lily, l978 . . . . . . . . . . . . . . . . . . . . 88 A6. Influence of temperature and fertilizer/amendment treatments on pedicel height (cm) of 'Ace' Easter lily, 1978. . . . . . . . . 89 A7. Analysis of variance. 'Ace' Easter lily scorch experiment, 1978 . . . . . . . . . . . . . . . . . 90 A8. Analysis of variance. Effects of temperature and fertilizer/amendment on nutrient content of 'Ace' Easter lily leaves, scorch experiment, 1978. . . . 91 A9. Analysis of variance. Effects of temperature and fertilizer/amendment on soluble salts, pH and elemental content of 4 growing media, 'Ace' Easter lily scorch experiment, l978. . . . . . . . 92 A10. Fresh weight (g) of 'Ace' Easter lily basal plate and roots over time, soil-less media experiments, 1977 and 1978. . . . . . . . . . . . . . . . . . . 93 All. Fresh weight (g) of 'Ace' Easter lily shoots over time, soil-less media experiments, 1977 and 1978 . 94 vi Table Page A12. Fresh weight (g) of 'Ace' Easter lily stem roots over time, soil-less media experiments, 1977 and 1978. . . . . . . . . . . . . . . . . . . . . 95 A13. Fresh weight (g) of 'Ace' Easter lily scales over time, soil-less media experiments, 1977 and 1978. 96 A14. Analysis of variance. Effect of growing medium on leaf loss, leaf scorch, scorch rating, root rot and disease rating of 'Ace' Easter lily, soil-less media experiment, l978. . . . . . . . . . . . . . 97 A15. Analysis of variance. Effect of growing medium on shoot length, leaf count and bud count of 'Ace' Easter lily, soil-less media experiment, 1978 . . 98 A16. Analysis of variance. Effect of growing medium on salts, pH and elemental content of 8 growing media, soil-less media experiment, l978. . . . . . . . . 99 A17. Analysis of variance. Effect of growing medium on nutrient content of 'Ace' Easter lily leaves, soil-less media experiment, 1978. . . . . . . . . 100 A18. 1 Analysis of variance. Effect of growing medium on leaf scorch, leaf loss and root rot of 'Ace' Easter lily, soil-less media experiment, 1977 . . 101 A19. Analysis of variance. Effect of growing medium on shoot length, leaf count, bud count and root growth pf 'Ace' Easter lily, soil-less media experiment, 1 977. . . . . . . . . . . . . . . . . . . . . . . 02 A20. Analysis of variance. Percent air porosity of soil- less media. . . . . . . . . . . . . . . . . . . . 103 A21. Influence of temperature and media on surface growth of Rhizoctonia solani . . . . . . . . . . . . . . 104 A22. Influence of temperature and media on surface growth of Fusarium oxysporum . . . . . . . . . . . . . . 105 A23. Influence of temperature and media on surface growth of Cylindrocarpon radicola. . . . . . . . . . . . 106 Figure LIST OF FIGURES Effect of temperature and fertilizer/amendment on scorch count of 'Ace' Easter lily, 1978 Effect of temperature and fertilizer/amendment on scorch rating of 'Ace' Easter lily, 1978. Effect of temperature and fertilizer/amendment on bud count of 'Ace' Easter lily, 1978. Effect of temperature and fertilizer/amendment on leaf count of 'Ace' Easter lily, 1978 . Effect of temperature and fertilizer/amendment on total plant height of 'Ace' Easter lily, l978 . Effect of temperature and fertilizer/amendment on pedicel height of 'Ace' Easter lily, l978 . Fresh weights over time, 1977 soil-less media experiment. . . . . . . . . . . . . . . Fresh weights over time, 1978 soil-less media experiment. . . . . . . . . . . . . . . Percent air porosity of soil-less media and soil control, 1978. ' . . . . . . . viii Page . 35 37 . 45 47 49 51 55 . 64 . 68 I. LITERATURE REVIEW Introduction The Easter lily, Lilium longiflorum Thunb. is a major floricultural crop in the United States which is grown pri- marily as a pot plant for the Easter holidays. The extensive research that has been conducted on this crop has focused on the commercial grower's key goals, which are: (a) To time the crop for Easter, (b) to develop as many flowers as possible, and (c) to control plant height (De Hertogh, 1974). Additional investigations have focused on nutritional, physiological, insect and disease problems. Two cultivars - 'Ace' and 'Nellie White' - comprise the bulk of Easter lilies used by the commercial industry today. The appearance of leaf scorch on 'Ace' has recently been a major concern of the industry and has stimulated renewed investiga- tions into the cause of this problem. Forcing Program Commercial Easter lily cultivars require a warm-cool-warm temperature cycle for growth and development (Stuart, 1967). The forcing procedure accelerates and mimics this cycle. Field- grown bulbs are harvested in late summer, at which time the apical meristem is vegetative (De Hertogh, 1974). Following harvest, bulbs are placed under cool, moist conditions (296 - 10°C) for six weeks) This cold requirement can be satisfied in one of three ways: Natural cooling, precooling or controlled temperature forcing (De Hertogh and Carlson, 1969). After this requirement has been met, the bulbs are placed in a warm (16C -18°C) greenhouse to promote floral initiation, organo- genesis, maturation and anthesis (De Hertogh, 1974). To successfully force Easter lilies, De Hertogh and Wilkins (1971) devised a three-phase schedule that is based upon the natural developmental cycle. The phases are: (1) Production - propa- gation and field-growing of the bulbs, (2) programming - to satisfy the cold temperature requirement, and (3) greenhouse - a follow-up phase that takes the vegetative bulb to anthesis within a certain period of time in order to meet an annually fluctuating Easter date. During the greenhouse phase, growers must contend with a number of Easter lily problems. These include leaf scorch, diseases, insect predation, excessive plant height, flower abortion, variable maturity within the crop and undesirably low light intensity. Research indicates growers can avoid or effectively eliminate these problems by selecting a good planting medium, using proper fertilizer formulations and rates, practicing preventive disease control, watering care- fully, using long-day photoperiod treatments when necessary, and using growth regulators to control plant height. Leaf Scorch In the 1940's and 1950's the 'Croft' lily was the most widely used cultivar for forcing. Growers, however, experi- enced a great deal of leaf scorch with this lily. Stuart (1949) first reported this injury, and described scorch as a semi- circular necrosis at the leaf margin close to the tip. Initial symptoms appear during the twelfth week of forcing in the green- house, the "buds visible stage" on the cultivar 'Ace' (Carlson, et a1., 1976). This disorder was intensively studied and numerous fac- tors were implicated, including low humidity, high temperature and deficient soil moisture (White, 1940), mineral deficiencies and nutrient imbalances (Seeley, 1950, 1951; Seeley and Velazquez, 1952; Haney, 1952; Stuart, 1949; Stuart, et a1., 1952), low soil pH (Shanks and Link, 1959; Stuart, et a1., 1952), high soluble salts (Kohl, et a1., 1960), excess boron (Kohl, et a1., 1960; Roberts, et a1., 1951), lithium toxicity (Furuta, et a1., 1973) and disease (Bald, et a1., 1955, 1957). Seeley (1950) grew 'Croft' lilies in sand to determine their response to various mineral nutrient deficiencies and the relationship of these deficiencies of leaf scorch. He found scorch was not directly caused by a deficiency of nutrients in the solution; plants grown in complete solution had as much or more injury than those grown with deficiencies. He postu- lated the concentration and ratio of nutrients in the solution may have an important influence on the occurrence of scorch. In addition, fertilizer conditions in the field may influence the response of lilies to nutrient deficiency treatments and the occurrence of burn in subsequent forcing. Work by Roberts, et al. in 1951 supported Seeley's hypothesis. Several studies have shown applications of nitrogen during forcing will decrease the incidence of scorch on 'Croft' lilies (Roberts, et a1., 1952; Seeley, 1951; Seeley and Velaz- quez, 1952). Haney's work (1952) revealed high N fertilization effectively controlled scorch only in the presence of adequate calcium. Bald, et a1. (1955) supported Haney's findings. Widmer (1957) showed the importance of the initial N content of the soil medium. Soils high in N produced minimal scorch, even without subsequent N fertilization, whereas lilies grown in low N soil had much scorch. Addition of ammonium sulfate reduced symptoms in the latter case. A nutritional study conducted by Shanks and Link (1959) revealed the importance of relationships between soil pH, lim- ing and fertility on scorch incidence of 'Croft' lilies. By reducing soil acidity and maintaining high N fertility, scorch was reduced. Soil applications of Ca also reduced the amount of scorch. The use of high levels of N reduced scorch in limed soil or in low acidity soil with adequate Ca present. Low N or P levels were associated with yellowing and browning of lower leaves. These findings indicated there was no marked correlation of either scorch or the breakdown of lower leaves with the concentrations of several elements found in the leaves; i.e. leaf damage was not directly related to any one of the elements studied. Evidence on the role of pH is contradictory. In Seeley and Velazquez' study (1952), some N fertilization treatments completely eliminated leaf burn, even though the soil pH dropped from an initial 6.6 to 4.5 - 4.9 at the end of the experiment. Stuart, et a1. (1952) showed scorch was most severe in very acid soils and was largely eliminated by increasing pH with heavy Ca applications. They were not sure whether scorch was due to toxic amounts of Al or Mn in acid soil or to a deficiency of Ca or Mg, which are usually present in such soils. Applications of Mg alone, however, did not alle- viate scorch symptoms and actually increased the amount of scorch in another study (Seeley and Velazquez, 1952). Although Li toxicity has been shown to cause leaf scorch on 'Croft' lilies (Furuta, et a1., 1973), contradictory evi- dence exists on the effect of excess 8. Kohl, et a1. (1960), concluded plants are relatively sensitive to 8 during forcing, whereas Furuta, et a1. (1973) stated typical scorch symptoms did not develop when toxic levels of B were applied. None of the reported research on 'Croft' lilies has demonstrated a conclusive causal relationship for leaf scorch. However, recommendations for control were made (Boodley, 1967; Stuart, 1952; Seeley, 1951; Shanks and Link, 1959). These included regular fertilization with N and P-containing minerals and increasing the pH of acidic soils with heavy applications of Ca. The severity of the problem, though, even- tually led to replacement of 'Croft' by 'Ace' and 'Nellie White' cultivars. In recent years, growers have experienced leaf scorch injury on 'Ace' lilies. Renewed investigations revealed a number of possible causes, some of which were implicated on 'Croft' lilies. An interaction between soil pH and phosphate fertilization has shown low pH (5.0) coupled with regular or triple superphosphate causes severe scorch, whereas at higher pH (6.5), scorch is significantly reduced. The use of di- calcium phosphate at either pH resulted in no scorch (Marousky and Woltz, 1975). Similar results were reported on gladiolus (Waltz and Marousky, 1975) when superphosphate was used. Other studies have also implicated regular and triple superphosphate (Widmer and Wilkins, 1976; Marousky and Woltz, 1977; Carlson, et a1., 1976) and perlite (Carlson, et a1., 1976) as causes of lily leaf scorch. These substances all contain relatively high levels of fluorine: Superphosphate - 1.0 to 1.6% F; triple superphosphate - 1.3% F; perlite - 17 ppm F (Widmer and Wilkins, 1976). German peat also has a high F level, 3.9 ppm (Conover and Poole, 1976). This data has led to investigations of the role of F in leaf scorch of Easter lilies and other floriculture crops in the Liliaceae family. Applications of superphosphate, triple superphosphate and aqueous hydrofluosilicic acid to soil media produced necrotic leaf margins and tips of Freesia hybrida (Gilbertson- Ferriss and Wilkins, 1978). Fluoridated irrigation water, growing media containing F-contaminated soil amendments, and superphosphate fertilizer all significantly increased foliage F concentration and leaf tip necrosis on Chlorophytum comosum (Wilkerson and Lingamon, 1978). In the latter study, necrosis and foliage F concentration were reduced by increasing Ca and soil pH levels, and by decreasing temperature and light in- tensity. Leaf scorch in Chlorophytum, Dracaena and Cordyline was induced by root-absorbed F (Conover and Poole, 1974; Poole and Conover, 1973). At low pH, plants fertilized with super- phosphate had leaves with more scorch and higher F content than plants grown without superphosphate. Woltz (1964; et a1., 1953) had similar results with gladiolus. In experiments on 'Ace' Easter lilies, Marousky and Woltz (1975) made direct applications of F as NaF to bulbs grown in sand. Plants with NaF had scorch closely correlated with levels of NaF. Bulbs grown without NaF had no scorch. The same pat- tern of scorch was observed from NaF as from superphosphate. 'Ace' lilies fertilized with superphosphate, NaF and N03-N or NH4-N developed similar numbers of scorched leaves (T1210 and Seeley, 1976). In treatments lacking NaF, plants fertilized with NH4-N still developed some scorch, whereas those receiving N03-N had no scorch. In a recent study (Marousky and Woltz, 1977), soil and plant analysis showed a high positive correlation between superphosphate and leaf scorch. Soil-borne F was influenced by the source of N fertilizer and lime rate. The most severe scorch occurred on plants grown in soils that had the lowest pH and highest F concentration. The research cited above presents definitive evidence of the harmful effects of F on many plants in the Liliaceae family. Both soil- and air-borne F can induce leaf scorch symptoms, with slight differences in the pattern of necrosis (Woltz, 1964; Fires, 1976b). Peterson (1976) described the incorporation of F into the plant from the soil: Soluble F is absorbed through the basal portion of cuttings or via roots of actively growing plants. It is then translocated in the vascular system to the leaves, where it accumulates. When toxic levels are reached, marginal burn or foliar chlorosis followed by necrosis result. The effectiveness of maintaining high Ca levels in the soil medium in order to control leaf scorch is based upon the hypothesis (MacIntire, et a1., 1942) that additive F compounds pass into the relatively insoluble CaF form after soil incor- poration. Work by Poole and Conover (1973) on Cordyline indirectly confirms this conversion. They demonstrated the amount of soluble F is influenced by pH and Ca levels of the soil; F decreased as pH increased, with Ca possibly playing a role in rendering the F insoluble. Hurd-Karrer (1950) found the addition of CaF to limed and unlimed soil resulted in no injury to collard plants, whereas addition of HFZ to unlimed soil severely stunted the plants. Her work showed liming greatly reduced the uptake of F when applied as HFZ and NaF. Sheldrake, et a1. (1978) confirmed these results. To control leaf scorch on 'Ace' Easter lilies, commercial growers are presently advised to adjust the soil pH to 6.0 to 6.5 using limestone or dolomitic limestone, and to replace the N portion of liquid feed with CaNO3 (Peterson, 1976); avoid using perlite (Carlson, et a1., 1976; Rathmall, 1975) and super- phosphate (Rathmall, 1975; Carlson, et a1., 1976; Peterson, 1976); use water which has less than 0.25ppm F (Rathmall, 1975); and avoid environments which accelerate the rate of trans- piration and subsequent uptake of F (i.e. high light intensity, excessive air movement and extremely high temperatures) (Rathmall, 1975; Peterson, 1976). For growers who still wish to use perlite, Henley and Poole (1976) suggest two to three heavy leachings to remove F, plus the addition of lime to adjust the pH of the medium to 5.5 to 6.8. lO Planting Medium In recent years, commercial growers of ornamental con- tainer crops have increasingly utilized soil amendments (perlite, vermiculite, calcined clays, rice hulls, bark, peat, sawdust, etc.) and manufactured soil-less media instead of preparing their own soil mixes. Quality, cost and availability of soil components are the major factors involved in choosing a parti- cular growing medium, along with specific requirements of the crop being grown. Poole and Tayama (1976) reported in 1973, the average grower's costs for making one cubic yard of growing medium was $33 ($43/m3). This figure includes: (a) Cost of ingred- ients, (b) labor preparation and handling, (c) specialized equipment involved, (d) soil sterilization, and (3) cost of fertilizers and amendments. Manufactured soil-less mixes ranged in price from $32 to $54 per cubic yard ($44 to $61/m3). The higher price of soil-less media is offset by the potential shortcomings of field soil. The latter is becoming more scarce, and container-crop growers must watch for possible contamination from herbicides, insects, weed seeds and pathogens (White, 1975). Steam sterilization, needed to control these pests, can release potentially toxic amounts of Mn, Al and other salts (White, 1975). 11 The choice of planting medium for Easter lily forcing is an important one due to leaf scorch injury and diseases that can severely reduce the quantity and quality of the final market product. The basic growing medium for Easter lilies should provide good drainage and aeration, yet have a high moisture holding capacity (Boodley, 1967). The initial nutrient content should be low to avoid burning the roots (Kohl, et a1., 1960). While several studies have analyzed the effects of various fertilizer treatments on the incidence of leaf scorch, few have been conducted on performance of lilies in different growing media. Boodley and Sheldrake (1963) grew 'Ace' lilies in four media and found 50% peat : 25% vermiculite : 25% perlite pro- duced the most flowers/plant, whereas soil-grown plants had the fewest number. They concluded light weight media were equal or superior to the soil mix (9 loam : 6 sphagnum peat : 4 perlite : 2 coarse sand). 'Ace' lilies grown in media amended with rice hulls had more flower buds than those grown in soil:sand:peat, but flowering was delayed 2 - 3 days (Einert, 1972). Rice hull media was lighter in weight and had improved drainage, but moisture retention was lower, thus needed more frequent water- ing. Einert concluded the influence of hulls on lily growth was either due to the indirect result of improved soil aeration or the possible contribution of nutrient elements, or both. 12 White (1975) studied growth of 'Nellie White' lilies in various ratios of mushroom casing soil and sphagnum peat. Osmocote 14:14:14 or Peters 14:7:7 fertilizer was incorporated into the media, and no additional fertilization was made. Results indicated nearly equal parts of the two components provided the best combination of physical and chemical proper- ties for lily production. These studies have illustrated the value of soil-less mixes for growing Easter lilies. However, there are a number of drawbacks that should be considered by the grower before utilizing these mixes. One of the benefits claimed by manu- facturers of soil-less media is their uniformity with respect to proportions of ingredients and fertility levels. Fires (1976a) examined the fertility levels of several packaged media and found variations up to 1000% between bags of the same mix. Research conducted at the Pennsylvania State Soil and Forage Testing Laboratory (Anon, 1977) indicated that in twenty commercial mixes tested, one out of five were capable of killing or injuring plants. Some mixes had excessive soluble salts, N and/or K levels. Others contained low P and/or K levels. The pH of several samples was under 5.5, which would affect the availability of various fertilizer elements. 13 Peat is a widely used component of soil-less media. A study of plant pathogens in peat (McCain, 1976) discovered that products labelled “no fungi", "sterilized", and/or "weed free" were in fact contaminated. Five species of Pythium were isolated from various peats, some of which were pathogenic, and Fusarium was found in all the samples tested. Sterility of the growing medium is not always beneficial. Another study on peat (Glynn, 1972) showed tomatos grown in Fusarium oxysporum-inoculated peats had less fungal infection as the previous cultivation period of the media increased. This effect may have been due to an increase in competitive microflora population with successive cropping. Work by Hoitnik, et a1. (1975, 1977a, 1977b) on composted hardwood bark has shown this medium to be superior to peat- sand and uncomposted bark media for growing ornamentals that are susceptible to root rot diseases. Leachates from fresh bark composts lysed Phytophthora cinnamoni zoospores and cysts, and sporangium production was reduced (1977a). Since leachates from two-year-old composted bark lacked these inhibitors, the authors hypothesized that its suppressive effect was due to chemical and biological rather than physical factors. The absence of root diseases on plants produced in bark compost was also attributed to antagonistic microorganisms in the bark (1977b). Control of Fusarium in composted bark was equal to 14 control in sterilized peat after two soil drenches with Benlate (1977b). The composting process is also valuable because it destroys phytotoxins contained in the bark. Bolton (1977) studied disease development in several growing media. Results showed that in soil-less media, both root rot disease severity on geranium cuttings and persistence of Pythium splendens were high when compared to unsterilized soil:sand:peat. This was due to a lack of antagonistic and competitive organisms in the soil-less mixtures. Soil reaction can also affect the microbial population. Marshall and Alexander (1960) found in acidic soils there was little or no inhibition of Fusarium by other microorganisms. In higher pH soils, inhibition was due to competition for available N. By adding inorganic N, this inhibition was overcome. The authors suggested incorporating organic matter low in N to sterile soils so that bacteria can out-compete Fusarium. Easter Lily Root Rot Disease Complex Easter lilies are susceptible to several diseases, caused by fungi, bacteria and viruses. Forsberg (1975) and Wescott (1971) have published lists of lily diseases and their respective causal agents. The most troublesome diseases for commercial growers are the root, bulb and stem rots. A complex 15 of fungi and bacteria are responsible, consisting of Fusarium oxysporum Schlecht f. lilii Imle, Cylindrocarpon radicola Wollenw., Pythium splendens Braun, Pythium ultimum Trow, Rhizoctonia solani Kuehn, Phytophthora paraSitica, Phytophthora cactorum, and Pseudomonas spp. (Raabe and Hurlimann, 1970; Wescott, 1971; Forsberg, 1975; Bald, et a1., 1973). Three species of mites have also been implicated: Rhizoglyphus echinopus Fumouze and Robin (Baker and Wharton, 1952), R; hyacinthi de. (Latta, 1939), and R. robini (Lindquist, 1976). Pathogenicity and virulence of these causal organisms have been investigated (Baker, 1957; Bald and Solberg, 1960; Bald, et a1., 1969, 1971, 1973; Raabe, 1975). Interactions between microorganisms were observed and found to be highly important. Raabe (1975) found that 'Georgia' and 'Harson' lily roots infected with necrotic flecks virus complex (Brierly and Smith, 1944) were more severely damaged by Pythium splendens than roots without virus symptoms. Bald, et a1. (1960, 1969, 1973) discovered a number of antagonistic and synergistic interactions among lily pathogens. Certain isolates of Cylindrocarpon, barely capable of tissue invasion, prevented Pseudomonas from infecting bulb scales (1960, 1969). Mild or severe variants of Fusarium, when combined with Pseudo- monas, caused very severe rotting (1960, 1969, 1973). Tricho- derma, a fairly ubiquitous saprophyte, can invade dead tissues and compete with one or more lily pathogen in lesions (1969). 16 One source of these pathogens is field soil. When lily bulbs are harvested from the field, some soil usually remains on the scales and roots. The pathogens may have already invaded the bulbs. In order to eradicate these organisms, growers dip the bulbs in fungicides prior to planting. Fusarium, Cylindro- carpon and Rhizoctonia are all ubiquitous parasites, and neces- sitate sterilization of any soil- or peat-containing mixture. In addition to bulb treatments, growers should follow rigid sanitation measures to prevent development of rot diseases. Reliance upon fungicides has been heavy. Raabe and Hurlimann (1970) found a combination of soil drench and bulb dip provided better control than either alone. Benlate was effective against Rhizoctonia and Fusarium, whereas Dexon and Terrazole (Truban) controlled Pythium. In 1973 they reported monthly soil drenches gave better control than pre-plant treatments alone. During shipping from field grower to greenhouse forcer, bulbs are kept cool, but growth and development may continue. This activity produces heat, and temperatures may rise inside the container to levels favorable to pathogenic fungi on or in the bulbs (Bald, et a1., 1973). If so, dipping the bulbs upon arrival and prior to planting may be too late. Bald, et a1. (1973) dipped bulbs in Benlate prior to shipping and found this procedure to be worthwhile. Resistance to Benlate, however, has been observed in Penicillium corymbiferum, which 17 causes a storage rot of lilies (Duineveld and Beijersbergen, 1975). In 1975, some cases were also noted where Benlate did not effectively control Fusarium oxysporum on hyacinth and gladiolus, members of the Liliaceae family. The control of bulb mites is an important aspect of good sanitation. Lindquist (1976) found that the amount of root rot in untreated lily plants was essentially the same as in fungicide-treated plants. He suggested bulb mites may have been damaging the roots and lower stems so extensively that the rate and frequency of the fungicide applications was in- capable of preventing root rot. By applying both fungicide and miticide, less rot occurred, indicating that mite con- trol can improve root rot control and the performance of fungicides. Porosity The importance of planting media to successful Easter lily production has been noted. One of the main considerations in selecting the proper medium is porosity, as lilies require good drainage and aeration, coupled with high moisture holding capacity (De Hertogh, et a1., 1977; Boodley, 1967). The ideal medium satisfies these contradictory needs by holding as much moisture as possible without reducing aeration. 18 Several investigations have pointed out the moisture holding capacity of container media is quite different from that of field soils (Bunt, 1961; Hendrickson and Veihmeyer, 1941; Joiner and Conover, 1965; Matkin, et a1., 1969). Con- tainers have a limited depth; a boundary exists at the bottom, in contrast to a continual soil column in the field. This boundary constitutes a barrier to free drainage. Container size and depth affect the porosity of the medium (White and Mastalerz, 1966; Hendrickson and Veihmeyer, 1941; Green and Adams, 1977; Spomer, 1976; Hanan and Langhans, 1963). Due to this limited depth, soils which provide ade- quate aeration in the field may not necessarily do so when placed in containers. This inadequacy is partially explained by a loss of natural porosity after digging and compaction in the container (Wildon and O'Rourke, 1964). Compaction is often accompanied by reduced water holding capacity, drainage, aeration, water infiltration rate and possibly root penetration (Poole, et a1., 1968). For these reasons, numerous organic and inorganic amendments have either been added to or substituted for field soils in order to increase the number of large pores and improve drainage and aeration (Mastalerz, 1977). There is considerable literature on the physical and ‘chemical pr0perties of various media components (Self, 1976; Koths, 1976; Self, et a1., 1967; Waters, et a1., 1970; Wildon 19 and O'Rourke, 1964; Cappaert, et a1., 1974; de Boodt and Ver- donck, 1972; Goh and Haynes, 1977; Poole and Waters, 1972; Matkin, 1968). A satisfactory planting medium for container-grown crops should have 10-25% air space after drainage and 35-50% water holding capacity by volume (Conover, 1967; Self, 1976). According to Matkin (1968), lilies require 5-lO% air space after drainage for adequate root growth. It is therefore important that the chosen medium's porosity be determined. Buscher and van Doren (1973) and Gessert (1976) outline simple measurement procedures. Particle size of the medium is extremely important in container production. The larger and more uniform the par- ticles, the greater the effect of depth on water removal and 02 supply (Hanan and Langhans, 1963). The smaller the par- ticle size, the greater the depth necessary to achieve the minimum 02 supply of the particular plant (Hanan and Langhans, 1963). As Paul and Lee (1976) noted, it is possible that plants grown in two different media having the same porosity will respond differently because the distribution of air- filled pores and the fineness of the pores may differ. The addition of perlite, rice hulls, vermiculite, cal- cined clays, sphagnum peat or bark will improve the porosity of a soil-based medium (Matkin, 1968; Mastalerz, 1977; Koths, 1976; Self, et a1., 1967). Again, particle size of the amendment 20 is a critical factor. If fine bark, peat, sand or vermiculite are used, aeration will decrease (Self, 1976; Mastalerz, 1977). Another important consideration is decomposition of the organic amendments (peat, bark, sawdust, wood shavings) which causes shrinkage of the medium. This shrinkage reduces the air spaces, resulting in decreased aeration and an increase in water holding capacity (Self, 1976). Porosity of the Easter lily medium is also important in relation to the root rot disease complex. Several investi- gators have studied the effect of 02-C02 levels in the rhizo- sphere on fungal growth and disease development in plants (Bergmann, 1959; Papavizas and Davey, 1961, 1962; Stolzy, et a1., 1966; Klotz, et a1., 1965, 1968; Curtis and Zentmeyer, 1949; Newcombe, 1960; Raney, 1965; Wiersum, 1977). Bergmann (1959) stated that low 02 or accumulation of C02 or both may affect the activity of soil microorganisms and thus cause changes in the mineral nutrient supply. Grable (1966), how- ever, claimed that gaseous transfer through air spaces within the plant may make it independent of soil aeration status if nutrients and water supply are adequate. These air spaces may become saturated with water, requiring 02 levels above 21% for normal growth to occur. Transpiration by plants causes water to flow from micro- organisms as well as from soil particles (Raney, 1965). The first change that occurs when soils are drained is emptying 21 of the large pores. Raney postulated that discontinuous moisture changes affect microorganisms well before an appre- ciable change ingross moisture content of the soil occurs. The moisture content of the soil directly affects the growth of fungi. Rhizoctonia develops best under moderate moisture conditions, whereas Pythium and PhytOphthora prefer very wet soils (Baker, 1957). Papavizas and Davey (1961) found saprophytic activity of Rhizogtonja was higher when soil moisture was maintained at 20-50% of its moisture holding capacity than at 60-90%. The former range is quite similar to the suggested range (Conover, 1967; Self, 1976) for growing container crops. Therefore Rhizggtgnia can be a problem even in a well-drained medium. Papavizas and Davey (1962) later found that Rhizoctonia's saprophytic activity was inhibited by 10-20% C02. Degree of inhibition depended upon C02 concentration, type of soil and inoculum potential. This decreased activity could not be attributed to 02 deficiency. The authors also discovered that the pathogenic phase of the fungus was more sensitive to C02 than its active saprophytic phase. Production of Fusarium oxysporum f. cubense chlamydospores is inhibited by C02 and soil flooding (Newcombe, 1960). These factors initially increase conidial production, but a coloni- zable substrate must be present for fungal survival since 22 conidia are short-lived in soil. Long-term survival of Egégglgm is dependent upon chlamydospore production (Newcombe, 1960). In their studies of bean root rot, Miller and Burke (1965, 1977) found plants grown in Fusarium solani f. sp. phaseoli in- fested soil were more severely damaged by the pathogen when subjected to short periods of 02 deprivation than plants grown in well-aerated soil. Root rot, which is aggravated by low oxygen diffusion rates (00R), is the principal cause of yield reduction and plant stunting that result from temporary excessive wetting of soil in Fusarium-infested fields (Miller and Burke, 1977). Even though 02 may be adequate in air- filled pores, it can be deficient at the root surface if the ODR is low. Klotz, et a1. (1965) studied the distribution of root- rotting fungi in soils and concluded the 02 concentration is an important factor. Their work also supported previous reports that Phytophthora spp. thrive under low 02 levels. In a study on Phytophthora root rot of citrus, Stolzy, et a1. (1966) found root decay was caused mainly by inadequate 02. Infection of citrus roots by Phytophthora is a function of zoospore production and ability to reach the roots. In fine- textured soils, root damage was attributed to low 02, because the small pores blocked zoospore motility. In coarse-textured soils, injury was due to the fungus; large pores filled with water allowed for rapid zoospore transport. 23 Klotz, et a1. (1968) also investigated Phytophthora root rot of avocado seedlings by varying watering regimes and 02 levels. Results indicated at low 02 levels, all watering treatments had much root rot whether inoculated with the fungus or not. At high 02 concentrations, the effect of Phytophthora on root rot damage was more apparent. These results contradict earlier work by Curtis and Zentmeyer (1949), who reported that fungal attack of avocado seedlings was most rapid at the highest 02 level. They performed their study in nutrient solutions, however, as opposed to soil. 24 II. OBJECTIVES Commercial bulb production is a major portion of the floriculture industry. The Easter lily and other bulbous speCies grown for holidays and particular seasons require rigid forcing procedures. To improve bulb production and forcing, research has focused on the cold requirement needed for bulbing and floral development. Photoperiod, an important factor in Easter lily production, has also been studied extensively. Leaf scorch and root rot diseases have been major problems for Easter lily growers. Although several factors have been implicated as causal agents of leaf scorch, results are in- complete. Costly, time-consuming and sometimes ineffective use of fungicides has been the method for controlling the root rot diseases. The trend toward increased usage of manufactured soil- 1ess media has created problems for the commercial flori- culturist. Researchers have suggested components of these media contribute to leaf scorch of Easter lilies. The major objective of this study was to investigate the role of fluorine, found in some soil amendments and fertilizers, on leaf scorch of Lilium longiflorum Thunb. cv. Ace. The combined 25 effect of growing medium, temperature and fertilizer on the amount of scorch was analyzed. Previous work by Laemmlen (unpublished data, 1976) indi- cated a significant difference between several soil-less media on lily growth and root rot development. A second objective was to further study the effects of these media on fungal dis- eases and growth of 'Ace' Easter lilies. 26 III. MATERIALS AND METHODS Bulbs of Lillgm longiflorum Thunb. cv. Ace were received from United Bulb Company (Mt. Clemens, Michigan) in late October 1976 and 1977. Upon arrival, the bulbs were precooled at 5°C for six weeks in moist peat. All growing media were analyzed before and after each experiment by the Michigan State University Soil Testing Lab in East Lansing, Michigan and by Dr. Frank Marousky at the USDA Southern Region Federal Research Service in Bradenton, Florida. Both laboratories used the saturation paste extract method. Soil flouride (F) content was measured only at the Florida lab. Leaf tissue analysis was performed by the Michigan State University Plant Analysis Lab, and leaf F content was measured by Dr. Marousky. Nitrogen content was determined by the Kjeldahl method, K by flame photometer, F by the procedure of Waltz and Marousky (1975) and all other elements by a direct reading spectrograph. 27 Effect of Media, Fertilizer and Temperature on Leaf Scorch On December 9, 1977, 240 20.3 - 22.9cm bulbs were planted in 15cm clay pots. A 2.5cm layer of gravel covered the bottom of each pot. Bulbs were planted nose—up. Prior to planting, bulbs were dipped in a benomyl-diazoben mixture for 30 minutes. The bulbs were planted in one of the following medial fertilizer combinations: (a) 1:1:1 soil:peat:Turface (BASF Wyandotte Corporation; Wyandotte, Michigan) plus dicalcium phosphate (0-41-0 with 23% Ca), (b) 1:1:1 soil:peat:Turface plus superphosphate (0-20-0 with 20% Ca), (c) 1:1:1 soil:peat: perlite plus dicalcium phosphate, or (d) 1:1:1 soil:peat: perlite plus superphosphate. Dicalcium phOSphate was incor- porated at the rate of 1.5kg/m3, and superphosphate at 3kg/m3. During greenhouse stages I and II (DeHertogh, 1974), the bulbs were grown at 17°C night/20°C day temperature. The greenhouse had no temperature modification system other than automatic vents controlled by thermostats and cooling fans, thus fluctuations occurred. One application of Osmocote 14—14-14 (Sierra Chemical Company; Newark, California) at 9g/pot was made as a top dress on December 28, 1977. Weekly fertilization with 120ppm Peters 20-20-20 (Allentown, Pennsyl- vania) was provided for the duration of the experiment. At 28 four-week intervals, the pots were drenched with diazoben- pentachloronitrobenzene. Plants were hand-watered as needed. On February 27, 1978, the "buds visible stage", the plants were separated into the following greenhouse temperature re- gimes: (a) 13°C NT/16°C 01, (b) 17°C NT/20°C DT, (c) 20°C NT/23°C 01. All four media/fertilizer treatments were repre- sented at each temperature. The experimental design was a split plot in a completely randomized arrangement, with tempera- ture as the main plot and media/fertilizer as the sub-plot. There were four blocks within each main plot and five obser- vations per block. Due to the three temperature regimes, flowering occurred over a several-week period, at which time the experiment was terminated. The following data were recorded: Number and‘ type of flower buds, height to pedicel and total plant height measured from the soil line, total leaf count, number of scorched leaves/plant, and scorch rating. For the latter measurement, 0 designated no scorch, 1 = slight, 2 = moderate and 3 = heavy scorch. In determining scorched leaves, only those with marginal necrosis were counted. For leaf tissue analysis, thirty leaves were removed from the lower-middle zone of each plant, dried in a forced air drying oven at 80°C, and ground in a Wiley mill. 29 Effect of Soil-less Media on Lily Growth and Root Rot Disease DEveTopment On December 8, 1976, 288 16.5 - 17.8cm bulbs were planted as outlined above. Plants did not receive a pre-plant fungici- dal dip. The bulbs were planted in one of the following media: (a) 1:1:1:1 soil:peat:sand:Turface, (b) Ball Growing Mix (Ball Seed Company; West Chicago, Illinois), (c) Jiffy-Mix (Jiffy Products of America; West Chicago, Illinois), (d) Jiffy- Mix Plus, (e) Metro-Mix 200 (W.R. Grace and Company; Cambridge. Massachusetts), (f) Metro-Mix 300, (g) Pro-Mix BX (Premier Brands, Inc.; New York, New York), or (h) Redi-Earth (W.R. Grace and Company). Pots were placed in an 18.3°C greenhouse in a randomized complete block arrangement. Due to the green- house's environmental control system, temperatures fluctuated throughout the experiment. Fluctuations ranged from 16.5°C to 29°C. Osmocote 14-14-14 at Qg/pot was applied as a top dress on January 6, 1977. Plants were hand-watered as needed. Samples consisting of two pots/block/treatment (total = 48 bulbs) were collected at 30-day intervals over a four-month period. The following data were collected: Fresh weights of scales, shoots, stem roots and basal plate plus roots; shoot length; leaf number; percent live roots; meristem diameter (first month only); bud count; and disease rating. The rating scale (1 - lO) reflected the amount of lesions present on the roots, with l signifying 0-10% infection, 2 = 11-20%, etc. 30 Only dying roots and live roots with lesions were considered. Plant segments were cultured on various media at each sampling date to determine what fungi were present. In 1976, the final sampling was conducted on March 29. In addition to the above parameters, yellow and scorched leaves were counted and root production and root rot were evaluated. A l6-square grid consisting of 12mm squares was pressed against the root ball at two locations. For root production, the number of squares containing visible roots were recorded. For root rot, those squares with dead and/or rotted roots were recorded. Scorched leaves were collected, dried and analyzed for F content only by Dr. Marousky. The experiment was repeated with the following modifications. Lilies were potted up and placed in a 17°C NT/20°C DT green- house on December 6, 1977. Osmocote was applied on December 28. At the end of the experiment, leaf samples were collected from the top and bottom halves of the shoot, and analyzed for com- plete nutrient content. All other aspects of the trial were similar to the 1976-77 experiment. Porosity_Determination of Soil-less Media The porosity of the seven soil-less media and the soil control were measured. The procedure of Gessert (1978) was used, with slight modifications. Eight 15cm plastic pots, with corked drainage holes, were filled with the dry media to the 31 inner rim. The media were slowly wetted, using warm water, until saturated. The volume added to each pot represented the total porosity of the medium. The pots were then set in trays and the corks removed. Then the pots were covered with aluminum foil and the trays with plastic sheeting to reduce evaporation from the media surfaces and drained water, respectively. The pots were allowed to drain for twelve hours, and the collected water was measured. This volume was equivalent to the air space in the drained media. The total volume of the pot was also deter- mined. By using the following formula, the percent air space (percent of the total volume of the drained medium that is occupied by air) of each medium was calculated: volume of dra1ned water x 100 Percent A1r Space = total Volume of pot The procedure was replicated four times. Measurement of Fungal Growth in Soil-less Media Phytophthora, Fusarium, Cylindrocarpon and Rhizoctonia isolated from Lilium longiflorum Thunb. cv. 'Ace' bulbs were used. A Pythium species and a second Phytgphthora isolate from lily were supplied by Dr. Robert Raabe (Department of Plant Pathology. University of California, Berkeley). Due to contamination problems with the Pythium and Phytophthora spe- cies, these fungi were eliminated from the experiment. 32 To increase the inoculum supply, flasks containing barley grain were inoculated with the fungi, according to the proce- dure outlined by Dr. Charles Schneider (personal communication, 1977). 1500st of barley were soaked overnight in 860mls of distilled water. The excess water was removed, and the barley was placed in 250ml flasks and autoclaved for 45 minutes. The next day the flasks were re-autoclaved for 90 minutes, then inoculated with fungus-permeated agar pieces. Flasks were plugged with aluminum foil-covered sterile cotton and incu- bated in a dark location for 30 days at room temperature. The seven soil-less media and one soil control were placed in clay pots, saturated with sterile distilled water and allowed to drain 24 hours to reach field capacity. The media were not watered again. 50mls of each medium were placed in individual sterile glass petri plates with covers. One fungus propagule (= one barley grain) was centered on top of each medium. Two sets of plates were prepared, one for each temperature. A 5°C and a 17°C incubator were used; these temperatures corres- pond to the cold requirement and greenhouse forcing tempera- tures, respectively, used for Easter lilies. In addition, a non-inoculated petri plate of each medium was incubated as a control. To serve as indicators of fungal growth, each fungus was plated onto potato dextrose agar and incubated at the two temperatures. In sum, there were 35 plates per incubator (3 fungi x 9 media + 8 controls). 33 IV. RESULTS AND DISCUSSION Effect of Media, Fertilizer and Temperature on Leaf Scorch Initial symptoms of scorch appeared in late January 1978 on a few plants. As this was quite early (Carlson, et a1., 1976), the possibility of fungal infection was investigated, with negative results. Temperature and fertilizer/amendment influenced the amount of leaf scorch. Plants grown in the superphosphate/ perlite medium at 16°C 01 had the greatest number of scorched leaves (Figure 1), whereas those in dicalcium phosphate/ Turface at the same temperature had the least scorch. In general, the amount of scorch‘decreased as temperature in- creased. Regardless of soil amendment, plants fertilized with superphosphate had more scorched leaves and greater scorch per leaf than those receiving dicalcium phosphate (Figure 2). These findings on superphosphate and perlite concur with pre- vious studies (Widmer and Wilkins, 1976; Marousky and Woltz, 1977; Carlson, et a1., 1976; Widmer and Woltz, 1976). Leaf tissue nutrient analysis revealed the temperature and fertilizer/amendment treatments affected the concentration of several elements, and the interaction was significant at or above the 5% level for N, P, Ca, Mg, Mn, Fe, B and Al (Table A8). —_ _‘(—' “—QKVVW‘W Figure 1. 34 Effect of temperature and fertilizer/amendment on scorch count of 'Ace' Easter lily, 1978. Medium 1 - Dicalcium phosphate/Turface Medium 2 - Superphosphate/Turface Medium 3 - Dicalcium phosphate/Perlite Medium 4 - Superphosphate/Perlite 35 F umzomm “may mmahcmmmZMH >¢D «N "N am . em . m. 1 i0 4. a asaouz . m canon: .. . N escomz co m ..oo.ofl v zauouu ..oo.mfl oo.o~ anOJ HOUODS (1NU18 838 SBAUBT OBHOUOOS) —.‘5.1":I'.Ir?wv-rrr ‘ ER..— Figure 2. 36 Effect of temperature and fertilizer/amendment on scorch rating of 'Ace' Easter lily, 1978. Medium 1 - Dicalcium phosphate/Turface Medium 2 - Superphosphate/Turface Medium 3 - Dicalcium phosphate/Perlite Medium 4 - Superphosphate/Perlite 37 N mmzwmm Huey wmzhmmmmzme >¢o mu ~N mm b“ P p P - u d u - a caucus m :DHQM: N :Duow: v zzuow: oo.N ONIIUU HJUODS 38 Fluoride content was significant only between temperature treatments, and levels were not high enough to cause severe scorch. However, there was a high linear correlation between scorch and Na and Zn concentrations (Table 1), which has not been mentioned in past scorch investigations. Shanks and Link (1959) found a high negative correlation between Na content and scorch on 'Croft' lilies. Plants grown in media fertilized with superphosphate had higher Zn levels than those receiving dicalcium phosphate, and perlite-grown plants had higher Na levels than Turface-grown plants (Table 2). There was also a high correlation between fertilizer/amendment treatment and scorch (Table l). Fluoride levels in the soil media were low, but differ- ences between treatments did exist (Table 3). Several nutrient levels, soluble salts and pH significantly differed between temperatures and/or fertilizer/amendments (Table 3); however, only F content had a high positive correlation to scorch count and rating (Table 4). The lower the temperature, the higher the F level in the soil (Table 3). F content was also higher in soils amended with perlite and in soils fertilized with superphosphate. Contrary to a report by Marousky and Woltz (1975), use of dicalcium phosphate did result in some scorched leaves, as opposed to no scorched leaves (Figure l). 39 Table 1 Linear correlation coefficients for scorch count and rating in relation to leaf analysis, 'Ace' Easter lily scorch experiment 1978. DEPENDENT VARIABLE INDEPENDENT ( Scorch Count Scorch Rating VARIABLE F-test r F-test r Replicate 0.29 Ns 0.08 0.01 Nsx -0 01 Fertilizer/Amendment 19.87 **** 0.55 22.10 **** 0.57 Temperature 3.94 ** -O.28 1.59 NS -O.18 N %) 0.34 NS -0.08 0.06 NS 0.04 K (%) 0.52 NS 0.11 0.30 NS -0.08 P (%) 0.29 NS -0.08 0.23 NS -0.07 Na (ppm) 8.99 *** 0.40 7.11 *** 0.37 Ca (%) 0.001 NS -0.005 0.32 NS 0.08 Mg (%) 0.22 NS -0.07 0.64 NS -0.12 Mn (ppm) 1.29 NS -O.16 0.21 NS -0.07 Fe (ppm) 1.69 NS 0.19 0.75 NS 0.13 Cu (ppm) 2.72 * 0.24 2.16 NS 0.21 8 (ppm) 2.82 * 0.24 1.82 NS 0.20 Zn (ppm) 5.03 ** 0.31 5.66 ** 0.33 A1 (ppm) 1.37 NS 0.17 0.24 NS 0.07 F (ppm) 0.46 NS 0.10 1.70 NS 0.19 All 3.57 **** - 2.95 *** - x F-test * significant at 10% level. ** *** **** NS significant at 5% level. significant at 1% level. significant at 0.1% level. not significant 41) . .pu>o_ up an aeouwupcm_m h e .Fm>a_ ap.o on u:au.c.:aam <\a x A o .ocaucc.=aam no: a .Po>op a,.o “5 oeuuccacm_m <\a ._m,m_ um um ocau_c_=m_m <\a x A .e a ..asap um um menacccem.m «\a L .Po>u— no— we «cmuwu—cmwm <\m x h .—o>op u~.o an unauwmwcmrm .po>u— np.o an acou'mwcmvm (\u x h .<\m .h >3 <\u ..msap “F be 5:56.».cm2m ._o>o_ <\m x p .po>u_ n_.o an unmoveF=mvm <\m .pm>o~ mm as acuorm_cmvm h z u_.o as ucoopuwcmrm¢mp uo_ um unmovewcmwm <\u .» m .po>o~ no_ we acco'mwcmpm <\u x h x ._6>6P mm on ocauac_cmam «\a x e .Fm>o_ um um “coupeccm.m (\a x e s ._o>op up.o as ucauwe_cm_m <\m .Fo>m_ up an acoowwwcmvm h u .mco.»mov_aos Lace mo names new weapo> N o.m o~p mm ~.—¢ m.__ on, ec— no.0 ~m.~ veep mm.o m.m ~.m o»_FLoa\muocamogaLoa:m poom~\pzoo~ m.m mpm um —.mm e.m New amp No.0 so.~ maop mm.o o.¢ w.m wow—coa\oumgamoga Esvopuuwo poom~\pzoo~ ~.m o- mm o.me o.N_ no. em. ¢~.o wo._ —oo_ mm.o m.e m.m mooucah\oumgamo;nsoa=m hoom~\hzoo~ c.m mop no «.me m.m Nap ~p~ -.o No.— poop mo.o —.¢ u.m ouueesh\muocnmogn Eavupoowo poom~\kzoo~ o.~ m—— we ~.we m.~ vmp NF, oo.o pn.~ mo—N pc.o p.v ~.m cuppcon\ouogamocaeoa=m kaoomxpzosp ~.m we no ..mn e.~ amp mmp mm.o ov.~ sump mm.o ..e ~.m ourFL6m\ouoznmoza Esvopauvo kaoowxpzon— ..s c- mm n.vm ~.~— m—N mm. o~.o o~.— mwm— mo.c ~.e m.m uuuueah\ouognmogngoaam pcoo~\»zomp m.o mop cu m.~e ~.m em. an. m~.o co.~ owm— no.o ~.v ~.m conveahxuuugamogn savupauwo hmoomxpzosp o.m cow we u.oe m.op mom ep_ oo.o —o.— mmmp um.o o.e m.m «uppcoa\muozamozneuazm hooopxpzom— ~.o cap —m m.~m o.pp omp mmp e~.o mm.— “cow mo.o ~.¢ o.n. mew—Loa\uuesnmoca Esau—euro beam—\hzom— c.m an. em o.kn o.op amp -. ~m.o ao.~ nee, Pk.o o.e c.o auaeeah\auagamo=atoa=m ec.o.\hz.m. co.m comp nae a~.mm Lo.m xoo— upw— um~.o :eo.— >owm— zeo.o xo.v so.m wouwezhxouosamo;n aswopcu+o hooop\hzom— :83 :53 can: can: :53 :53 2.9: my 3 :53 E E E . 25 3.; m p< cN m :u mm e: no oz a x z unwaveme<\ Lo~wp_ucom ALV ocauaeoneop ~.m~mp .ucmswcmnxo cocoon .mm>~m_ xp__ Loumum .oo<. mo acoucoo “aortas: co acmeucmEM\em~w~_uemm new oesuucmaeou mo muoweem " N opus» 41 .—u>o— up.o an «coo—upcopm (\u x h .<\m ...... 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A... ..~ ..A ..A ... ... .... ... .A.....\.A....... s........ A...~\Az.A. ... .... ... .... .... ... ... mm. .. .... ..... ... ......A\.A.A.....L.a.. A...~AA2.A. ... .... A... .... .... ... ... ... c. ... .... ... ......AA.A.A...A. a.....u.. A...~\Az.A. ~.. A... ~.~. .... .... ... ... AA. AA. A... AA... ... .A.....\.A.A.A...L.... .....AAA... ... A... ..~. A... .A.. ... ..A ... Ac. ~.A .... ... .A..L..\.A.A...;. s........ A....\Az... ~.. ..~. N... .... .... ... ... ... ~A. N... .A... ... ......A\.A...A.A...... A....AAz... .... ...A. .... ..... A.... x... .A... A... >.... 3.... A8... A... ......A\.A.A...A. s........ A....\Az... Mn. 3 A: E .83 .53 .53 .53 .83 .83 32.5. ... 2:. .... .u A z A .2 .. x a z .A... Acme...2<\..A...ALAA AA. 0333 9.39.338. ~53. £33.... :o. .5563... 533-»... u m .3... 42 ** *** **** NS significant at 5% level. 1% level. significant at 0.1 level. significant at not significant.’ Table 4 Linear correlation coefficients for scorch count and rating in relation to soil analysis, 'Ace' Easter lily scorch experiment, 1978. DEPENDENT VARIABLE INDEPENDENT Scorch Count Scorch Rating VARIABLE F-test r F-test r Replicate 0.29 NS 0.08 0.01 N5x -0.01 Fertilizer/Amendment 19.87 **** 0.55 22.10 **** 0.57 Temperature 3.94 ** -0.28 1.59 NS -0.18 pH 1.75 NS 0.19 0.04 NS 0.03 Soluble Salts (mmhos) 0.44 NS 0.10 0.08 NS 0.04 N (ppm) 0.001 NS 0.005 0.01 NS -0.04 P (ppm) 2.74 * 0.24 2.36 NS 0.22 K (ppm) 2.45 NS 0.22 0.57 NS 0.11 Ca (ppm) 0.27 NS 0.08 0.94 NS 0.04 M9 (ppm) 0.10 NS 0.05 0.17 NS -0.06 Nitrate N (%) 0.35 NS -0.09 0.59 NS -0.11 K(%) 3.82 * 0.28 1.31 NS 0.17 Ca (%) 0.07 NS 0.04 0.05 NS 0.03 Mg (% 0.33 NS -0.08 0.83 NS -0.13 F (ppm) 13.55 **** 0.48 9.42 **** 0.41 All 3.10 *** - 2.42 ** - x F-test * significant at 10% level. 43 Soil analysis run by Michigan State University's Soils ‘ lab and by Dr. Marousky indicated soluble salts levels (mmhos) were extremely high (Table 3), with no visible effect on plant growth or vigor. Bud count generally decreased as temperature increased (Figure 3). Stage II in greenhouse forcing, the time from floral initiation to buds visible in the foliage, is critical in establishing the number of flowers that will be developed (De Hertogh, 1974). A11 lilies were grown at 17°C NT/20°C DT during Stage II, and this is considered the best setting for optimum bud count. Results of this experiment indicate that Stage III temperatures, from buds visible to anthesis, are also important in terms of ultimate bud count and development. Plants grown in superphosphate/Turface at 20°C DT had the highest bud count; those grown in dicalcium phosphate/per- lite at the same temperature had the lowest (Figure 3). Turface-grown plants had more buds than perlite-grown plants. In general, leaf count decreased as temperature increased (Figure 4). Highest leaf count occurred in dicalcium phosphate/ perlite medium at 16°C DT. whereas lowest count was found on plants grown in the same medium at 23°C DT. Both pedicel height and total plant height increased inith increasing temperatures (Figures 5 & 6). These results concur with previous findings (De Hertogh and Wilkins, 1971). Figure 3. Effect on bud Medium Medium Medium Medium 44 of temperature and fertilizer/amendment count of 'Ace' Easter lily, 1978. Dicalcium phosphate/Turface Superphosphate/Turface Dicalcium phosphate/Perlite Superphosphate/Perlite 45de Ill! 45 m mmawam aux: mmahcmmmzm» >¢o mw a“ pg 0 ch- w m a, oo.m p P p ‘11 4 d d 1 m zauow: A v :Duou: S :38: 10 N z:~om: l 1 tom.m uoo.m oo.b (lNUWd 836 3008) anDD GHQ Figure 3. Effect on bud Medium Medium Medium Medium 44 of temperature and fertilizer/amendment count of 'Ace' Easter lily, 1978. Dicalcium phosphate/Turface Superphosphate/Turface Dicalcium phosphate/Perlite Superphosphate/Perlite l 2 3 4 45 m mmawmm no“; manpcmmmzmp >¢o Su M“ p“ +g3 41- b 1 - m— P d p d ~11- m :DHom: A v caucus S zaeouc lmu N :zuou: a oo.m oo.b (lNUld 83d 8008) lNflOO 008 Figure 4. 46 Effect of temperature and fertilizer/amendment of leaf count of 'Ace' Easter lily, 1978. Medium 1 - Dicalcium phosphate/Turface Medium 2 - Superphosphate/Turface Medium 3 - Dicalcium phosphate/Perlite Medium 4 - Superphosphate/Perlite 47 no.2 manpcmmmZMH rag c mmame mu "N a“ p“ m" 0 fl 4 4, u #1, 4 » 0.0m m :zaomz soo.mm a e zauomz .IIIII/x .. ,///llm N z:_ouz goo om S ==.ou= eeo.mm IO 0.00“ (lNUld 83d SBAUBW] lNflOS 3631 Figure 5. 48 Effect of temperature and fertilizer/amendment of total plant height of 'Ace' Easter lily, 1978. Medium 1 - Dicalcium phosphate/Turface Medium 2 - Superphosphate/Turface Medium 3 - Dicalcium phosphate/Perlite Medium 4 - Superphosphate/Perlite 49 m mmame no % mmzpmmmmZMH >¢o ”N «N mm mm a zauow: N :zuom: .1111L9 GT1 v :3~om: m :Duou: m L a floo.0¢ I oo.m¢ Too.ow oo.mm (N3) lHOIBH lNHWd 16101 Figure 6. 50 Effect of temperature and fertilizer/amendment on pedicel Medium Medium Medium Medium #WN-J height of 'Ace' Easter lily, l978. Dicalcium phosphate/Turface Superphosphate/Turface Dicalcium phosphate/Perlite Superphosphate/Perlite 51 o mmson Hug. umapmmmmEMH »¢o MN «N mu ha ma 4 u “w u v u 4. “ mm a za~owz st N :zmou: n znaom: 9’ 1* ...mm v zauou: e (N3) lHOIBH 133103d 52. Plants grown in perlite were generally taller than those grown in Turface, irrespective of fertilizer used. Effect of Soil-less Media on Lily_Growth and Root Rot Disease Development In 1976-77, the number of scorched leaves was signifi- cantly different between the eight media, with no scorch in the control and the most in Pro-Mix Bx. This medium also had the highest leaf count, whereas Metro-Mix 200 had the lowest (Table 5). Fresh weight data revealed the media-time interaction was significant at the 1% level for scales, shoot and stem roots. For basal plate plus roots, only the main and sub- plot effects were significant, again at the 1% level (Table A10). In general, shoot and stem root weights increased from January to April (Figure 7). Basal plate plus root weights increased over the first three months, then dropped slightly by April. Scale weight decreased steadily over the four-month period. In 1977-78 media again affected the number of scorched leaves. The crop was more severely scorched in this trial than the previous year (Table 6). All soil-less media produced heavily scorched plants, whereas control plants had none. Results of soil analysis revealed a positive correlation of medium and the nutrients Mg (% of total salts), P and F to 53 Table 5 Influence of growing medium on leaf count and scorch count of 'Ace' Easter lily, 1977 soil-less media experiment.v Mediumw Leaf Countx** Scorch Countyi‘ri'z Control 75.8 ab 0.0 a Ball Growing Mix 70.5 ab 28.5 b Jiffy-Mix 76.2 ab 21.7 ab Jiffy-Mix Plus 75.3 ab 13.3 ab Metro-Mix 200 67.8 b 24.2 b Metro-Mix 300 76.7 ab 12.2 ab Pro-Mix BX 77.3 a 31.8 b Redi-Earth 74.5 ab 22.2 ab v Values are means of 2 observations/rep. with 3 reps. W Mean separation within columns by Duncan's multiple range test. Numbers followed by the same letter are not significantly different at the 5% level. X Indicates number of leaves/plant. y Indicates number of scorched leaves/plant. z F-test * significant at 5% level. ** significant at 1% level. 54 Figure 7. Fresh weights over time, 1977 soil-less media‘ experiment. FRESH WEIGHT (0) 55 12 LEQEND v " -e-scm.es 10m +snoor *8? + RTS 9» + STE" RT8 801* 60*) 40¢ 0 JRN FEB HRR RPR FIGURE 7 56 Table 5 Influence of growing medium on disease and leaf scorch of 'Ace' Easter lily, 1978 soil-less media experiment. Mediumt Leaf Loss"** Scorch Countv Scorch Rtg" Root Rotx *** *** ***y Control 1 ’ 6.2 c 0.0 a 0.0 a 10.8 abc Ball-Growing Mix 9.8 bc 36.2 b 2.8 b 7.1 c Jiffy-Mix ‘ 10.7 abc 45.0 b 3.0 b 10.1 bc Jiffy-Mix Plus 24.7 abc 47.2 b 3.0 b 14.2 ab Metro-Mix 200 14.5 abc . 35.5 b 2.8 b 11.4 abc Metro~Mix 300 6.8 c 38.8 b 2.8 b 10.8 abc Pro-Mix BX 28.8 a 50.0 b 3.0 b 15.0 a Redi-Earth 26.8 ab 55.7 b 3.0 b 13.2 ab t Mean separation within columns by Duncan's multiple range test. Numbers followed by the same letter are not significantly different at the 5% level. u Indicates number of dead or dying leaves/plant. V Indicates number of scorched leaves/plant. W Indicates degree of scorch. 0= none, 1= slight, 2= moderate, 3= severe. x Measured by a 16-square grid. Values indicate number of squares containing diseased or dead root tissue. y F-test ** significant at 1% level *** significant at 0.1% level 2 Values are means of 2 observations/rep. with 3 reps. 57 scorch count and rating (Table 7). Pro-Mix BX had the highest F content and the control the lowest, which agrees with the resultant degree of leaf scorch on plants grown in these media (Tables 6 & 8). Comparison of P and Mg content to the number of scorch leaves per medium is not a direct relationship. Soluble salts (mmhos), N (PPM). K (ppm) and Ca (ppm and % of total salts) all showed a high negative correlation to scorch. One-on-one comparison of these parameters to leaf scorch is inconclusive. It appears that leaf scorch is influenced by a complex interaction of various soil nutrient levels. Leaf tissue analysis results also showed a high positive correlation of medium and F to scorch (Table 9). Fluoride content was higher in lower leaves than upper (Table 10), but levels were inconsistent with actual leaf scorch., Plants grown in the control mix had no scorch (Table 6), yet their F content was higher than plants grown in Metro-Mix 300, which had 38.8 scorched leaves (Table 6). Leaf boron content was also highly correlated to scorch (Table 9); however, a direct relationship between concentration and number of scorched leaves does not exist (Tables 6 B 10). Phosphorus and Zn were negatively related to scorch (Table 9). In contrast, Shanks and Link (1959) reported a positive rela- tionship between scorch and P content. Again, a complex interaction of leaf nutrients seems to influence scorch. 58 Table 17 Linear correlation coefficients for scorch count and rating in relation to soil analysis, 'Ace' Easter lily soil-less media experiment, l978. DEPENDENT VARIABLE INDEPENDENT Scorch Count Scorch Rating VARIABLE F-test r F-test r Replicate 0.63 NS -0.17 0.015 nsx -0.03 Medium 16.27 **** 0.65 11.61 *** 0.59 pH 5.22 ** -0.44 5.10 ** -0.43 Soluble Salts (mmhos) 35.10 **** -0.78 40.00 **** -0.80 N (ppm) 24.44 **** -0.72 30.51 **** -0.76 mg 3.17 * 0.36 4.54 ** 0.41 11.69 *** -0.59 11.53 *** -0.59 ppm 34.03 **** -0.78 59.79 **** -0.86 Mg ppm 2.85 * -0.34 1.60 NS -0.26 Nitrate N (%) 3.76 * -0.38 4.56 ** -0.41 K (%) 0.056 NS 0.05 0.10 NS 0.07 Ca %' 13.44 **** -0.62 25.34 **** -0.73 Mg %) 6.24 ** 0.47 10.04 *** 0.56 F (ppm) 27.49 **** 0.74 32.81 **** 0.77 All 5.54 *** - 16.08 **** - x F-test * significant at 10% level ** *** *‘k'k'k NS significant at 5% level significant at 1% level significant at 0.1% level not significant. 59 ._a>a_ a_.o on Semu_c_emem pcmumewcmwm no: mz «:3. .Pm>mp x_ pm SemuPcwcmwm 44 ammu-a » mcowumumFamc mmccu cow memos mew mmzpm> x F.m N.o_ m.m m.wp wo.m o.wo m.mmp o.mN_ o.mm o.—mp om.~ m.m :ucmmuwumm ~.¢ e..p P.m P.4F ~o.e m.mo o.¢mp e.mm_ m.on o.m_N o_.N n.m xm xwzuoca N.m ¢.o~ m.m P.m~ mo.~ o.mpp m.~_N o.mmp o.mm m.mmm om.N m.m com xp21ocpwz p.m ~.w w.o ~.¢p m¢.~ o.mm o.m¢p o.omp p.¢m o.mmm om.N m.m ooN xwziocumz N.~ N.o— m.o m.op mu.~ m.NNP o.¢np o.oP— N.¢mp o.m~p o¢.~ p.m_ may; xwzixwwwn o.e m.m ¢.m m.op mo.N o.~w o.-— o.oo_ m.om o.~m~ om.N —.m xwzixwmww o.m _.m_ —.o— _.mp mm.~ m.-~ o.m- o.¢PN m.mop m.m~m oo.m m.m xv: mcwzocw ppmm N.m o.mp e.w p.m~ em.o o.mp_ m.mm¢ m.NmN ¢.¢m m.m¢m om.e o.m pocucou 11: . «weav haikuv A359 Amzv TIL Arrav A3; T32; TEL 72:; Amery onE. TSL ucwsmmgh & a u a Eng Egg sag Egg Egg sag mp—mm In a: no x z a a: mu x a z apnspom x.w~mp .mwmxpmcm —wom unmswgmaxm «puma mmmplpwomuumoa " m mpamp 60 Table 9 Linear correlation coefficients for scorch count and rating in relation to leaf analysis, 'Ace' Easter lily soil-less media experiment, l978. INDEPENDENT DEPENDENT VARIABLE VARIABLE Scorch Count Scorch Rating F-test r F-test r Medium 16. 27 **** 0.65 11. 61 ***x 0.59 Repl ta 0. 63 us -o.17 0. 01 NS -0.03 N if 0.17 NS -0.03 0.82 NS -0.19 K g% 0.10 NS 0.07 0.46 ns 0.14 P %) 10.14 *** -0.56 33. 03 **** -0.78 Na (ppm) 0.23 us 0.10 0.11 NS 0.07 Ca %) 0.11 NS 0.07 0.86 NS 0.19 Mg 1) 1.47 NS 0.25 3.76 * 0.38 Mm (ppm) 4.08 * -0.40 3.80 * -0.38 Fe (ppm) 3.57 * 0.37 3.28 * 0. 36 Cu (ppm) 0.08 ms -0.06 2.67 us -0. 33 B (ppm) 10.13 m 0. 56 10. 84 m 0. 57 Zn (ppm) 3.50 * -0. 37 6. 21 ** -0. 47 Al (ppm) 0.65 NS 0.17 0.67 NS 0.17 F (ppm) 16.49 **** 0. 65 8.96 *** 0. 54 All 8.12 *** 40.50 **** - x F-test * significant at 10% level ** significant at 5% level *** significant at 1% level **** significant at 0.1% level NS not significant 61 .44444 44.4 44 44464444444 4 .4 .44444 44 44 44464444444 4 x x .44444 44.4 44 44444444444 4 444 z 4 .44444 44.4 44 44464444444 4 4 z .z 4 .44444 44.4 44 44464444444 4 444 z > .44444 .44444 44.4 44 44464444444 4 .44444 44 44 44444444444 : z 44 44 44464444444 4 4 x .44444 44.4 44 44464444444 4 444 z e .44>44 44 44 44444444444 4 x .4264 4...: an “4443:4344 4 .4264 um um 2443:4434 : 4 .4432. .4284 can .544: 34:. 334424 942. 44444444 44:48 .4 .4264 a; an 4443:2544 4 x x .4264 um um 4433:4434 : 4 4454434440.. 9.4.45 .8 4.43.4. 9:4 42.424 .4 4.44 444 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44:44 44444-4444 4.44 444 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44:44 44 444-444 4.44 444 44 4.44 4.44 444 444 44.4 44.4 4444 44.4 4.4 4.4 44:44 444 442-4244: 4.44 444 44 4.44 4.44 444 444 44.4 44.4 4444 44.4 4.4 4.4 44444 444 444-4444: 4.44 444 44 4.44 4.44 444 444 44.4 44.4 4444 44.4 4.4 4.4 44244 4444 44: 44444 4.44 444 44 4.44 4.4 444 444 44.4 44.4 4444 44.4 4.4 4.4 44:44 44: 44444 4.44 44 444 4.44 4.4 444 444 44.4 44.4 4444 44.4 4.4 4.4 44:44 44: 4442444 4444 4.44 444 444 4.44 4.4 444 444 44.4 44.4 4444 44.4 4.4 4.4 44344 4444444 4.44 444 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 44444-4444 4.4 44 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 44 44x-4e4 4.4 444 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 444 442-4444: 4.4 44 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 444 442-4444: 4.44 44 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 4444 444-44444 4.4 44 44 4.44 4.4 444 444 44.4 44.4 4444 44.4 4.4 4.4 44444 444-44444 4.4 44 44 4.44 4.4 444 44 44.4 44.4 4444 44.4 4.4 4.4 44444 44: 4443444 4444 .m.4 444 444 44.44 44.4 4444 4444 444.4 444.4 44444 444.4 44.4 44.4 44444 4444444 44444 4.444 44444 44444 44444 44444 4.444 “"4 444 44444 444 444 444 444 444444444 4:4 44444: 4 44 44 4 44 44 e: 44 44 4 4 z mwnm— 44444044444593 02.4044. mmmT—vom 4.34400— XP: .43QO .mu<. mo acoucou ucotuac no 445.2494. 94.4395 we uummmm 4 0.. 032. 62 The l977-78 lily crop was more severely infected by root- rotting fungal pathogens than the previous year. Many plants were severely stunted. had aborted flower buds. and lost several lower leaves. There was a significant difference in the amount of root rot between the various media (Table 6). Ball Growing Mix had the fewest dead or infected roots. and Pro-Mix Bx the most. Leaf loss, the number of dead or dying leaves per plant, was also significant. This parameter is a visual indi- cation of root rot, improper fertility and spacing and possibly soil aeration problems. A comparison of root rot values to leaf loss supports this cause-effect relationship somewhat. Analysis of fresh weight data showed all organs had significant weight changes over time (Tables A10 - Al3). The time/media interaction was significant for scale fresh weight, and the development of stem roots was significantly affected by growing media. Plants grown in Redi-Earth and Jiffy Mix developed the most stem roots, whereas those grown in Pro-Mix BX and the control had the fewest such roots. Stem root fresh weights gradually increased with time (Figure 8). Shoots in- creased through March but dropped by April, which was to be expected due to the early Easter date. This could also be seen by the turnaround in scale fresh weight (as compared to 1977). which decreased from January to March, then increased during the last month. Plants had completed flowering and were beginning to channel their energies into vegetative reproduction. 63 Figure 8. Fresh weights over time, l978 soil-less media experiment. FRESH HEIGHT (G) 64 12 100 80 60 40 T r T JHN .L_E§§fl.0 -e- san53 49- 311001 + a? + RTS «4 STEH RTS t. FIGURE 8 65 i.e. bulbing. Basal plate plus root growth was strong only between January and February, probably due to successful infec- tion by fungal pathogens in the later months. Porositnyetermination of Soil-less Media The percent air porosity of the soil-less media and soil control are given in Table ll. Figure 9 illustrates the variability within and between media with respect to aeration. There was a significant difference in porosity between the eight media. Porosity was also found to be positively correlated to leaf scorch count and rating (Table 12). The control had the lowest porosity and no scorch, whereas Redi-Earth had the highest porosity and the most scorch in l978 (Tables 6 & ll). One possible explanation for this is stress; plants grown in the more porous Redi-Earth dried out quickly due to its large pore spaces and rapid drainage. This, combined with warm, sunny days could have increased the transpiration rate more so than on control mix-grown plants. According to Rathmall (l975) and Peterson (1976), high transpiration should be avoided in order to lessen the likelihood of scorch. 66 Table ll : Percent air porosity of soil-less media. Medium Meany Control 6.3 ex Ball Growing Mix 21.7 bc Jiffy-Mix 24.4 ab Jiffy-Mix Plus 24.3 ab Metro-Mix 200 12.7 dc Metro-Mix 300 l5.4 cd Pro-Mix BX l9.l bcd Redi-Earth 30.8 a x Numbers followed by same letter are not significantly different at 5% level, by Duncan's multiple range test. y Values are means of four replications. Figure 9. 67 Percent air porosity of soil-less media and soil control, l978. Medium Medium Medium Medium Medium Medium Medium Medium GDNGU‘I-wad Control Ball Growing Mix Jiffy-Mix Jiffy-Mix Plus Metro-Mix 200 Metro-Mix 300 Pro-Mix BX Redi-Earth 68 2:4omz 4 4 D b m unsung 1-«3 jL-h «vi-CD qL-m 1 q h—O—d 1-ou lb" 0 6N AllSOHDd 1N3383d 69 Table 12 : Linear correlation coefficients for root rot, leaf loss, scorch count and rating in relation to porosity, 'Ace' Easter lily soil-less media experiment, l978. ‘ .4 POROSITY PARAMETERS F-test r Medium 1.55 NS" 0.45 Root rot 0.25 NS 0.20 Leaf loss 3.20 NS 0.59 Search count 15.83 *** 0.85 Scorch rating 6.80 ** 0.73 All l3.45 * - x F-test *** NS significant at l0% level significant at 5% level significant at 1% level not significant. 70 Measurement of Fungal Growth in Soil-less Media The results of this investigation were inconclusive, as only one successful trial was completed. Data are located in the Appendix (Tables A2l - A23). The main problem confronted in this experiment was measuring fungal growth accurately. Mycelial strands were difficult to see with the unaided eye, especially if they wove above and below the medium's surface. Mo satisfactory method was devised to chart the daily progress of a particular strand without interfering with or contaminating the culture. 71 V. SUMMARY AND CONCLUSIONS Leaf scorch was greater in plants grown in superphosphate/ perlite than the other fertilizer/amendment treatments. The amount of leaf scorch generally decreased as temperature in- creased, possibly because plants grown under the lowest temperatures had a longer exposure to F in the soil, as data on these plants was not recorded until anthesis occurred. This is supported by the fact that soil F levels increased as temperature decreased. Soil F content was positively correlated to scorch. As expected, soils amended with perlite and/or fertilized with superphosphate had higher F levels than soils amended with Tur- face or fertilized with dicalcium phosphate. Plants fertilized with superphosphate also had higher leaf Zn levels, and those grown in perlite had higher leaf Na levels, both of which were positively correlated to scorch. Based on these findings, growers should avoid using perlite or superphosphate when forcing 'Ace' Easter lilies if leaf scorch is a major concern . 72 Most of the variability of scorch was accounted for by soil F levels, with some due to leaf Na and Zn concentrations. It appears, therefore, that F is the main factor responsible for Easter lily leaf scorch, although other nutrients also play a significant role. Plants grown in soils amended with Turface had higher bud and leaf counts than those grown in perlite. Perlite also produced taller plants than Turface, which can be undesirable, especially if high temperatures are being utilized to accele- rate forcing time in order to meet the Easter marketing date. This evidence further supports using Turface instead of perlite. Lower temperatures are desirable in terms of bud count, leaf count and plant height; but the greater incidence of scorch negates using lower temperatures. The soil-less media used all produced severe leaf scorch on Easter lilies in both l977 and l978. Medium and leaf tissue F content were positively correlated to scorch; however, a direct relationship between concentration and actual scorch count existed only for medium F levels. All seven soil-less media had high F levels due to the incorporation of F-contaminated perlite, peat or superphosphate. Fluoride again accounted for a majority of the variability of scorch. 73 The control medium had the highest level of soluble salts, N, Ca and K and the lowest F concentration. The first four parameters had high negative correlations to scorch. It seems plausible, therefore, that the interaction of these factors, combined with the low F level, was responsible for the complete absence of scorch on plants grown in this medium. Media which produced severely scorched plants had concentrations of these nutrients and soluble salts at the opposite extreme to the control. VUnfortunately, the relationship between leaf nutrient levels and scorch was not as straightforward. With respect to scorch, based on the results of this experiment, media con- taining F-contaminated amendments or fertilizers should be avoided. Root rot infection was severe in the l977-78 lily crop, with some media more conducive to fungal growth and survival than others. In terms of visible disease symptoms, plants grown in Ball Growing Mix, Metro-Mix 300 and the control lost the fewest lower leaves. However, the former two media pro- duced heavily scorched plants, negating their favorable disease ratings. If growers elect to use these soil-less media, an intensive disease prevention program using fungicides will be necessary, due to a lack of competitive, antagonistic micro- organisms often present in soil-based media. 74 Fresh weight data for both trials revealed certain trends in lily organogenesis over time. In order to feed and support a rapidly growing shoot, the plant expands its bulb root system and initiates a stem root system in mid to late January. Stem roots become increasingly important as the root-rotting complex invades the basal plate and roots, as was the case in 1977-78. Scale fresh weight gradually decreased over time, due to a depletion in stored carbohydrates which were used to nourish the growing shoot. Once anthesis and subsequent senescence occur, the flow of carbohydrates reverses, the scales are replenished, and bulbing occurs. Porosity of the soil-less media and soil control may account for the difference in stem root fresh weights between these media. Plants grown in more porous media (Jiffy-Mix, Jiffy-Mix Plus and Redi-Earth) developed more extensive stem roots than plants in the other media. The greater pore space provided both sufficient room and adequate gas exchange to stimulate root growth. These same media also produced the most severely scorched plants in 1977-78, partly due to high porosity and drainage. The correlation between porosity and leaf scorch was highly positive. The explanation here could be due to greater water stress for plants grown in the more porous media, a factor which has been linked to scorch. Plants grown in the control 75 medium had no scorch, and its porosity fell within the recom- mended 5-lO% range for Easter lilies. Evidently, porosity above lO% is not advantageous to lily growth in terms of leaf scorch, or root rot occurrence. There was no correlation between root rot and porosity. It was expected that the more porous media would provide unfavorable environments for the root rot patho- gens, especially Phytophthora and Pythium spp. The preliminary investigation to measure fungal growth in the soil-less media and soil control was inconclusive. Of the soil-less media tested here, the two which contained bark, Metro-Mix 300 and Ball Growing Mix, had relatively low leaf loss and root rot values, compared to the control. This trend was not evident in the experiment. Other media/disease studies have shown that bark suppresses fungal growth. Further work needs to be done to determine specifically what causes one soil- less medium to be more conducive to or suppressive of fungal growth than another. 76 VI. BIBLIOGRAPHY_ Anon. 1977. Research questions quality of commercial potting mix. Flor. Rev., Feb. 10, p. 137-8. Baker, E.w. and G.N. Wharton. 1952. ‘An Introduction to Acaro- logy. MacMillan Co., New York: N.Y} 465 p. Baker, K.F. (ed). 1957. The U.C. System for Producing Healthy Container-Grown Plants. Calif. Agr. Expt. Stat. Extens. Service Manual 23. Bald, J.G., A.M. Kofranek, O.R. Lunt. 1955. Leaf scorch and Rhizoctonia on Croft lilies. Phytopathology 45: 156-162. Bald, J.G. and P.A. Chandler. 1957. Reduction of the root rot complex on Croft lilies by fungicidal treatment and propagation from bulb scales. Phytopathology 47: 285-291. Bald, J.G. and R.A. Solberg. 1960. Antagonism and synergism among organisms associated with scale tip rot of lilies. Phytopathology 50: 615-20. Bald, J.G., A.O. Paulus, J.V. Lenz, P.A. Chandler, T. Suzuki. 1969. Disease control with pathogen-free bulb stocks for Easter lily improvement. Calif. Agr. 23(11): 6-8. Bald, J.G., T. Suzuki, A. Doyle. 1971. Pathogenicity of Fusarium oxysporum to Easter lily, narcissus and gladi- olus. Ann. Appl. Biol. 67: 331-342. Bald, J.G., A.0. Paulus, J.V. Lenz. 1973. Fungicidal dips for Easter lily bulbs . . . . treatment before ship- ment. Calif. Agr. 27(12): 8-10. 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TEMPERATURE (OC) Fertilizer/ Ferti l izer/ o o o o o 0 Amendment Amendment 13 NT/16 DT 17 NT/20 UT 20 NT/23 01 Means Dicalcium Phosphate/ 1.10 1.45 1.55 1.37 Turface Super phosphate/ 8.05 3.90 6.15 6.03 Turface Dicalcium phosphate/ 4.45 0.65 2.00 2.37 Perlite Superphosphate/ 17.25 11.55 6.00 11.60 Perlite l 1' 3.92 Temperature Means ‘ 7.71 4.39 85 Table A2 : Influence of temperature and fertilizer/amendment treat- ments on scorch ratingx of 'Ace' Easter lily, l978. Fertilizer/ Amendment Temperature (0C) Fertilizer/ Amendment 13°NT/16ODT 17°NT/2000T 20°NT/23ODT Means Dicalcium phosphate/ Turface Super phosphate/ Turface Dicalcium phosphate/ Perlite Superphosphate/ Perlite Temperature Means 0.45 0.55 0.45 1.10 0.95 1.10 0.95 0.50 0.55 1.55 1.60 1.10 1.01 0.90 0.80 0.48 1.05 0.67 1.42 x Scorch rating: 0= no scorch, l= slight, 2=moderate, 3= severe. Table Dicalc Superp Dicalc l Superpl I Tempen \ 86 Table A3 : Influence of temperature and fertilizer/amendment treat- ments on bud count (number/plant) of 'Ace' Easter lily, 1978. Temperature (0C) Fertilizer] Fertilizer] o o o 0 Amendment Amendment 13 111/15 01 l7°NT/20°DT 20 111/23 01 Means Dicalcium phosphate/ 6.25 6.15 5.75 6.05 Turface Superphosphate/ 6.50 6.60 5.90 6.33 Turface Dicalcium phosphate/ 5.95 5.50 5.65 5.70 Perlite Superphosphate/ 5.90 5.80 5.70 5.8 Perlite Temperature Means 6.15 6.01 5.75 87 Table A4 : Influence of temperature and fertilizer/amendment treatments on leaf count (number/plant) of 'Ace' Easter lily, l978. Temperature (0C) Fertilizer/ Fertilizer/ o o o o o 0 Amendment Amendment 13 NT/16 DT 17 NT/20 01 20 NT/23 DT Means Dicalcium phosphate/ 95.70 90.95 86.50 91.05 Turface Superphosphate/ 88.90 90.55 87.00 88.82 Turface Dicalcium phosphate/ 96.05 86.15 81.70 87.97 Perlite Superphosphate/ 87.80 86.80 89.70 88.10 Perlite Temperature Means 92.11 88.61 86.22 ( Tabl Dical Super Dicalfi Super Temper 88 Table A5 Influence of temperature and fertilizer/amendment treat- ments on total height (cm) of 'Ace' Easter lily, 1978. Temperature (0C) Fertilizer] Fertilizer] o 0 o o o 0 Amendment Amendment 13 NT]16 DT 17 NT/20 DT' 20 NT/23 01 Means Dicalcium phosphate] 40.00 43.50 43.42 42.31 Turface Superphosphate] 42.52 44.28 42.82 43.21 Turface Dicalcium phosphate] 44.08 46.90 52.30 47.76 Perlite Super phosphate] 45.82 46.72 46.78 46.44 Perlite Temperature Means 43.11 45.35 46.33 x Measured from soil level to top of plant. Table Dica Supe Dica Supe Tem; 89 Table A6 Influence of temperature and fertilizer/amendment treat- ments on pedicel height (cm) of 'Ace' Easter lily, 1978. Temperature (0C) Fertilizer] Fertilizer] o o o o 0 Amendment Amendment 13 111/15 01 17°111/20 01 20 111/23 01 Means Dicalcium phosphate] 29.13 31.88 32.20 31.07 Turface Superphosphate] 31.18 34.08 32.10 32.45 Turface Dicalcium phosphate] 33.93 35.00 39.22 36.05 Perlite Superphosphate] 36.1 35.42 35.30 35.61 Perlite Temperature Means 32.58 34.09 34.71 x Measured from soil level to base of pedicel. 90 .Pmuwuma co omen op mcwp Fmom seem umczmemz N .u:m_a mo no» op m:w_ Fwom seem cocammwz A .Fm>mp &P.o pm ucmuwwmcmwm the .Pesep R_ Be ueeuwewem_m es ._e>m~ am pm peeeeeeempm « pm¢p1e x mm Loccm «e ~oo.o mov.o “mm.o « mpo.o e mmo.o who.o o <\m x h ¢¢~.o es Noo.o «es mooo.0v «as mooo.ov «es mooo.ov «s: mooo.ov m A<\uv ucmsucms< \cm~wpwacmu xsem mooo.ov « Pmo.o mo_.o me moo.o «« moo.o « cmo.o N AFV mcsumcmqsmh me peach acaou pcaou mcwumm ucaoo “some: uzmwmz we muczom $8.. 25 sueoum :ucoum .133 . ~33an .mmmp .ucmewcmaxm :ucoom xpwp cmpmmm .ou<. .mucewcm> 4o mmmmpmc< u ~< mpnm» 91 ._e>o_ u_.o we Beau.c_em.n the: .Pmso. a. «e ueeu_cpempn «e. .Pmsep mm a. eeee.c_eoen .. .Fmsu. no, u. ueee.c,eawm . “new-“ x on soggy 8.. teemea e; 2.9““ a; 13.23.4153... :88 steed «84. 2:85 ..8.~ :88 ... «to; .<\ev acusecae< mm.o m._ ~_.~ .5.mo.o .._.n m~._ enn.~ ....en.e_ ....~.~m esssem.~ sesesm.ep 44., op._ m \ee~__.ueee x...¢.o am.~ m.o .e_p.¢ m~.~ ve.o sop.” ...»..m eessmo.- mo.~ ..em.m eo._ we._ N Apv «Lauocmasu» he Fume» Assay .neav Renew Asaev «can. 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Analysis of variance. 97 Effect of growing medium on leaf loss, leaf scorch, scorch rating, root rot and disease ANALYSIS OF VARIANCE MEASUREMENT Source df MS F Leafl.oss Total 47 - - x Medium 7 519.94 5.54 ** Rep 2 112.02 1.19 Error 14 93.88 - Sampling 24 - - Scorch Count Total 47 - - Medium 7 1749.51 10.18 *** Rep 2 392.14 2.28 Error 14 171.93 - Sampling 24 - - Scorch Rating Total 47 - - Medium 7 6.47 105.57 *** Rep 2 0 06 1.00 Error 14 0.06 - Sampling 24 - - Root Rot Total 47 - - Medium 7 38.47 6.73 *** Rep 2 5.45 0.95 Error 14 5.71 - Sampling 24 - - Disease Rating Total 47 - - Medium 7 13.14 1.07NS Rep _ 2 0.77 0.63 Error 14 12.29 - Sampling 24 - - x F-test _ — ‘i * significant at 5% level ** significant at 1% level *** significant at 0.1% level NS not significant Ta 98 Table A15: Analysis of variance. Effect of growing medium on shoot length, leaf count and bud count of 'Ace' Easter lily, 5011- less media experiment, 1978. ANALYSIS OF VARIANCE MEASUREMENT Source df MS F Shoot Length Total 47 - - Medium 7 132.85 1.69 NS x Rep 2 2982.15 37.87 **** Error 14 78.75 - Sampling 24 - Leaf Count Total 47 - - Medium 7 145.69 2.14 NS Rep 2 189.56 2.79 * Error 14 67.99 - Sampling 24 - - Bud Count Total 47 - - Medium 7 1.70 1.99 NS Rep 2 1.19 1.39 NS Error 14 0.85 - ’ Sampling 24 - - x F-test * significant at 10% level ** significant at 5% level *** significant at 1% level **** significant at 0.1% level NS not significant eeeo.c.eu.n as: m: —0>o— n—.o no acchvvccrm on. .esep xp 3. ueee.e.euem 11 .oso. um u. ueeeve.ea.n 1 enou-d x 2 e8: m_.o _m.e o..o “5.8 an.. o_.o a..o ea.o oo.o o_.o .o.c . e_.o ~ xue_a use. ou.~n at. pa.v— n: mo.— .0 mo.m o... oo.- «0 mm.m coo -.—— cc vn.v cot mN.n— coo aa.m as. aw.“ «i Ns.v n ovum: . n~ ..ae» E E E E .83 ...-.3 .83 .83 .83 ~83 .Hwiv .... 2. «8:8 . ..m a: do u 1 e a: .u u a g o_e=.em (E 11 .ona— 3.8.7.098 3.8. «mo—1:8 .23: 9.283 a mo 23:3 .353? 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Effect of growing medium on leaf scorch, leaf loss and root rot of 'Ace' Easter lily, soil- less media experiment, l977. ANALYSIS OF VARIANCE MEASUREMENT Source df MS F Leaf Loss Total 47 - - Medium 7 19.33 1.24 NS Rep 2 14.25 0.92 Error 14 15.54 - Sampling 24 - - Scorch Count Total 47 - - Medium 7 532.71 4.55 *** Rep 2 190.40 1.40 Error 14 136.09 - Sampling 24 - - Root Rot Total 47 - - Medium 7 15.42 1.46 NS Rep 2 . 43.27 4.09 * Error 14 10.57 - Sampling 24 - - x F-test * significant at 5% level ** significant at 1% level NS not significant 102 Table A19 : Analysis of variance. Effect of growing medium on shoot length, leaf count, bud count and root growth of 'Ace' Easter lily, soil-less media experiment, l977. ANALYSIS OF VARIANCE MEASUREMENT Source df MS F Shoot Length Total 47 - - Medium 7 77.55 2.28 * x Rep 2 705.21 20.74 **** Error 14 34.00 - Sampling 24 - - Leaf Count Total 47 - - Medium 7 115.07 4.94 *** 1 Rep 2 166.02 7.13 *** Error 14 23.28 - Sampling 24 - - Root Growth : Total 47 - - Medium 7 1.47 1.06 NS Rep 2 2.36 1.70 Error ‘ 14 1.39 - Sampling 24 - - Bud Count Total 47 - - Medium 7 1. 50 1.95 NS Rep 2 1. 31 1.72 Error 14 0.76 - Sampling 24 - - x F-test * significant at 10% level ** significant at 5% level *** significant at 1% level **** ggnificant at 0.1 % level NS significant 103 Table A20 : Analysis of variance. Percent air porosity of soil-less media. Source df SS MS F Total 23 2047.75 - - Treatment (media) 7x 1668.14 238.31 9.42 **y Error 15 379.51 25.31 - X Loss of one degree of freedom due to one missing plot. y Significant at 1% level. .rCMPO 11||lll||111 m MPCOHUOchm $0 2.va 530.5 mumyczm :o gums new mczumLmQEmu mo mucmasmca .. ~N< 29.2. 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