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'44 15",} \{4’434 ‘lf {5515? fig?!) ., A” ’r‘ 1"}0'.‘ '3”)? L43," (1“), if '4' II/ ' w .4 $434.; 4- I "It” {Moll-"r - )vf' (' 134/" 749 '4; ’< 4:. 11313477“ '3'? $5 A l‘F’f‘, ' f; 4/55 ’ /1A( 1’4]! "é! 35’ :j"/’ '1] -:. fix ~ . PM"; ’34,; ' " ' “474w; Zia-“f. [47’ gr? Cé’ig’c'zw 4"“, frvluq .’.l I}! 1"- {Y1} W???" .‘J’. g". n; I.’ 45'” 42:? 0.30." .31! ‘ ”Q ,1'4- ‘Lfi'fifh ’lb gquODJoS III III // Cfilfli/flJ/WIVIE’ZSITY' ’UBRARIES I III . III W l’ M f I I II I I I IIIIIII 93 00551 4587 ’ YHESiS LIERARY Michigan State University This is to certify that the thesis entitled INVERTEBRATE PEST DAMAGE AND NUMBERS AFFECTED BY TILLAGE METHODS AND OTHER CULTURAL PRACTICES IN FIELD CORN presented by KATHLEEN M. SHARPE has been accepted towards fulfillment of the requirements for M.S. . ENTOMOLOGY degree 1n {WW/m? Major professor Date 7/99/27 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution MSU LIBRARIES “ RETURNING MATERIALS: Place in book drop to remove this checkout from your record. FINES will be charged if book is returned after the date stamped below. INVERTEBRATE PEST DAMAGE ANp NUMBERS AFFECTED 3v TILLAGE METHODS AND OTHER CULTURAL PRACTICES IN FIELD CORN By Kathleen Mary Sharpe A THESIS . Submitted by Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Entomology 1987 ABSTRACT INVERTEBRATE PEST DAMAGE AND NUMBERS AFFECTED BY TILLAGE METHODS AND OTHER CULTURAL PRACTICES IN FIELD CORN By Kathleen Mary Sharpe Invertebrate pest damage and numbers were affected by tillage, crop rotation, manure and irrigation in a factorial experiment designed to assess the effects of tillage methods and other cultural practices on the production and yield of field corn. Slug (Agriolimax reticulatus Muller) damage and numbers were highest in no-tillage treatments with rye (or red clover) cover- crops. Damage was positively related to the amount of plant residues on the soil surface. Slug damage was higher in continuous corn than in corn rotated after alfalfa. Slug damage levels were highest during the whorl stages of corn plant growth; slug damage was low during the seedling stages and was again low during the reproductive stages of corn growth. Slug numbers in continuous corn was highest in no-tillage with a cover-crop of rye. European corn borer foliar damage during the whorl stages of corn plant growth was lowest in the no-tillage with a cover-crop of alfalfa. Unidentified invertebrate damage during the seedling stage of corn plant growth was highest in no-tillage with a rye cover-crop. Flea beetle foliar damage during the whorl stages of corn growth was highest in no- tillage with an alfalfa cover-crop and was also higher in irrigated corn. To my mother Juliana M. Sharpe and father John Thomas Sharpe ACKNOWLEDGMENTS The list of supporters who enabled me to complete my thesis rivals it in length. I thank my mother, Juliana M. Sharpe, who gave me support in every area toward the completion of this goal. I thank my uncle Edward McKay for his encouragement and help. My deep appreciation goes out to the Department of Entomology, and to the Kellogg Biological Station (KBS) for permitting me to use their physical resources. I thank my advisor, Dr. Stuart Gage who has made abundant contributions to my program and to this project, not the least of which has been his generous financial support. He assigned me an ecologically relevant project on which I was allowed the opportunity to work independently. Though this process Dr. Gage has contributed substantially to my mastery of an interesting and current “hot spot" of agricultural research, to my ability to deal with other people, and to my growth as an individual. Deep felt gratitude goes to Dr. Karen Strickler who has been a mentor to me, and who has a deep commitment to helping young professionals. Dr. Strickler has contributed copious amounts of time as my editor and sound advice as my friend. Karen and her husband John Vinson were unstintingly generous in providing me with living space during the completion of my thesis. Dr. A. Earl Erickson of the Crops and Soils Science Department provided me with a technician to assist in data collection and entry. ThroUgh this project I have come to share Dr. Erickson's enthusiasm for the potential of no-tillage to conserve topsoil in field crop production. Dr. Bob Ruppel (whose encyclopedic knowledge of agricultural entomology is incredible in its scope and in its detail), opened new avenues to me by including me as a co-author in what turned out to be my first paper. He has also introduced me to researchers in the field of conservation tillage, and has always treated me as a colleague. Thanks to Dr. Porter of the Zoology Department for his help and for his contagious interest and enthusiasm. Thanks also to Dr. Cress and Dr. Reis who helped with the statistical analyses. Thanks also to Duby Wolfson for computer assistance. No better supporters and friends can be named than my fellow graduate students, especially Beth Bishop, Eva Butler, Nancy Campbell, Brian and Lauren Chambers, Ed Dawson, Bassey Eyo, Ellie Groden,Frank Drummond, Susan Jawitz, Bob Kriegel, Patricia Michelak, Aubrey Moore, Emily Olds, Tanya and Dave Prokrym and Bill Roltsch. Very special appreciation goes to Beth Bishop and Nancy Campbell. I thank my fellow “Children of the Corn", Kathleen Wiest and Pamela Carlton, technicians on this project in 1982 and 1983 respectively. Kathy's and Pam's sweat, blood, and in a few cases, tears are imbedded into this thesis. Thanks to Dr. George Lauff for his generous facilitation as director of KBS. Others whom I would like to acknowledge from the Kellogg Biological Station are Charlotte Adams, Jim Bronson, Richard Carlton, Carmen Cid-Benevento, Anne Clark, Alice Gillespie, John Gorentz, Scott Gleason, Harvey Liss, Tom Miller, Dorothy Spinner, Delores Teller, Steve Weiss, Shelley WiCkham and Alice Wynn. Thanks to Carolyn Hammarskjold, the librarian at KBS, for her excellent technical support (and often times moral support). I'd like to thank all the members of my Renew group for their spiritual support (especially Mary Mitchell and Mary Hennessey). Thanks also to the MSU Counseling Department (especially Linda Forest who taught me to keep breathing). For their genuine support and faith in my ability to attain this goal I thank all of my family members and friends, especially Howard Bass, Kim Boighnton, Evelyn and Ben Brown, Mindy and Dan Cubacub, Rose Cooper, Mary Keitleman, Randy Mays, Daniel and Carol McKay, Mary McKay, Robert McKay, Norma McKay, Paula McKay, Victoria and Bernard McKay, Vincent McKay, Kate and Jimmy Richerson, Lenay Shaffar, Sue Singler, Margaret Woods, and Anne Zoeller). Often times just the knowledge that all these people were with me in spirit was the only thing that kept me plugging away. It is to Becky Mather that l credit the professional appearance of this text; her input has been invaluable. TABLE OF CONTENTS LIST OF TABLES .................................................. viii LIST OF FIGURES .................................................. xi INTRODUCTION ................................................... 1 LITERATURE REVIEW . ............................................... 4 Descriptions and Terminology ................................. 4 Physical and Chemical Characteristics of Soil and Relationships to Invertebrate Organisms .............. 7 Effects of Tillage Characteristics on Pests of Com .............. 13 MATERIALS AND METHODS ...................................... 20 Study Location and Site Description .......................... 20 Experimental Design ........................................ 20 Site Management .......................................... 25 Invertebrate Pest Sampling Methodology ..................... 33 Slug Damage Measurements ................................ 43 Measurement of Percent Ground Cover ....................... 47 RESULTS ........................................................ 48 Slug Damage Description .................................... 48 1982 Damage Intensity ...................................... 48 1983 Damage Intensity ...................................... 50 1983 Damage Incidence ..................................... 50 Percent of Leaf Surface Area Damaged by Slugs ............... 58 Slug Numbers .............................................. 61 Summary of Slug Results .................................... 65 vi DISCUSSION .................................................... 66 Seasonal Occurrence of Slugs ................................ 66 Rotation ................................................... 67 Irrigation .................................................. 67 Manure ................................................... 67 Tillage and Ground Cover ................................... 68 Slug Conclusions . . ......................................... 69 APPENDIX A. Slug Statistics ....................................... 71 APPENDIX 8. European Corn Borer ................................ 77 Methods ................................................... 77 Results .................................................... 78 APPENDIX C. Corn Rootworm .................................... 91 Methods ................................................... 91 Results .................................................... 91 APPENDIX D. Other Invertebrate ................................. 96 Methods ................................................... 96 Results .................................................... 96 REFERENCES ................................................... 101 vii Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. Table 11. Table 12. Table 13. Table 14. Table 15. Table 16. LIST OF TABLES Fertilizer Applications .................................. Herbicide Applications ................................. Insecticide Applications ................................ Tillage Operations ..................................... Field Corn (Zea mays L.) Variety and Planting Dates ....... Cover-Crop Varieties and Planting Dates ................. 1982 and 1983 Tillage Treatments by Rotation ............ Damage Intensity Ratings for Invertebrates .............. 1983 Corn Growth Stages and CCMS Codes ............... 1982 and 1983 Survey Schedules ........................ Analysis of Variance (ANOVA) Table ..................... Slug Damage (Incidence): Rotation Comparisons during Early Whorl and Mid-Late Whorl Stages ........... Slu Damage (Incidence): Analysis of Variance Tables of t e Alfalfa/Corn (A/C), Corn/Corn (C/C), and Corn/Corn/Corn (C/C/C) Rotations during the Early Whorl Stages ..................................... Slug Damage (Incidence): Analysis of Variance Table of the Corn/Corn (C/C) Rotation during the Mid-Late Whorl Stages .......................................... Slug Damage (Incidence): Multiple Comparisons of Tillage/ Cover-crop Treatments in the Corn/Corn (GO and Corn/Corn/Corn (C/C/C) Rotations during the Early Whorl Stages . . ................................... Slug Damage (Incidence): Multiple Comparisons of ”Manure x Tillage“ Interaction in the Corn/Corn (C/C) Rotation during the Mid-Late Whorl Stages .............. viii 26 27 28 29 30 31 32 36 38 39 44 53 55 56 57 60 Table 17. Table 18. Table 19. TableIZO. Table 21. Table 22. Table 23. Table 24. Table 25. Table 26. Table 27. Table 28. Table 29. Table 30. Table 31. Percent of Total Leaf Surface Area Damaged by Slugs: Analysis of Variance Table of Tillage/Cover-crop Treatments in the Corn/Corn/Corn (C/C/C) Rotation during the Early Whorl Stages ..................................... Percent of Total Leaf Surface Area Damaged by Slugs: Multiple Comparisons of Tillage/Cover-crop Treatment in the Corn/Corn/Corn (C/C/C) Rotation during the Early Whorl Stages ..................................... Number of Slugs per Plant: Analysis of Variance Table of Tillage/Cover-crop Treatments in the Corn/Corn/Corn (C/C/C) Rotation during the Early Whorl Stages ........... Number of Slugs per Plant: Multiple Comparisons of Tillage /Cover-crop Treatment in the Corn/Corn/Corn (C/C/C) Rotation during the Early Whorl Stages .................. Number of Slugs per Square Meter: Analysis of Variance Table of Tillage/Cover-Crop Treatments in the Corn/Corn/Corn (C/C/C) Rotation after Harvest ............ Number of Slugs per Square Meter: Multiple Comparisons of Tillage/Cover-crop Treatment in the Corn/Corn/Corn (C/C/C) Rotation after Harvest ........................... Slug Foliar Damage Intensity Seasonal Distribution Statistics in 1982 ....................................... 1982 Slug Foliar Damage Intensity Statistics -- Alfalfa/ Corn Rotation ......................................... 1982 Slug Foliar Damage Intensity Statistics -- Corn/Corn Rotation .................................... Slug Foliar Damage Incidence Statistics during Early Whorl Stages in 1983 .................................. Slug Foliar Damage Intensity Statistics during Early Whorl Stages in 1983 .................................. 1982 European Corn Borer Foliar Damage Intensity Seasonal Distribution Statistics for Rotations ............. 1982 European Corn Borer Foliar Damage Intensity Statistics -- Alfalfa/Corn Rotation ........................ 1982 European Corn Borer Foliar Damage Intensity Statistics -- Corn/Corn Rotation .......................... 1983 European Corn Borer Foliar Damage Incidence -- M id-late Whorl Stages Rotation ......................... 62 62 63 63 64 64 72 73 74 75 76 81 82 83 84 Table 32. Table 33. Table 34. Table 35. Table 36. Table 37. Table 38. Table 39. Table 40. Table 41. Table 42. Table 43. 1983 European Corn Borer Foliar Dama e Incidence in Mid-Late Whorl Stages (ANOVA -- AI alfa/Corn Rotation) ............................................. 1983 European Corn Borer Foliar Damage Incidence in Mid-Late Whorl Stages (ANOVA-Corn/Corn Rotation) ..... 1983 European Corn Borer Foliar Damage Incidence in Mid-Late Whorl Stages (ANOVA -- Corn/Corn/Corn Rotation). ............................................ 1983 European Corn Borer Damage Incidence -- Mid-Late Whorl Stages in Irrigation ..................... 1983 European Corn Borer Damage Incidence -- Mid-Late Whorl Stages in Manure ....................... 1983 European Corn Borer Foliar Damage Incidence -- Mid-Late Whorl Stages of Tillage Treatment .............. Correlations of European Corn Borer Foliar Damage Incidence with Corn Plant Height and Corn Plant Stage .. .. 1982 Seasonal Distribution Statistics for Corn Rootworm Adult Numbers per Plant ............................... 1982 Corn Rootworm Adult Counts (#lplants) Statistics -- Alfalfa/Corn Rotation .................................. 1982 Corn Rootworm Adult Counts (#lplant) Statistics -- Corn/Corn Rotation .................................... 1983 Unidentified Invertebrate Foliar Damage Incidence for Tillage/Cover-crop Treatment Comparisons .......................................... 1983 Unidentified Invertebrate Foliar Damage Intensity for Tillage/Cover-Crop Treatment Comparisons .......................................... 85 86 88 89 90 93 94 95 98 98 LIST OF FIGURES Figure 1. Map of WK Kellogg Biological Station featuring Kalamazoo and Battle Creek ............................ 21 Figure 2. Aerial Photograph of WK Kellogg Biological Station showing plot locations ................................. 22 Figure 3. 1983 and 1983 Plot Maps, location A ..................... 23 Figure 4. 1982 and 1983 Plot Maps, location B ..................... 24 Figure 5. 1982 Crop Growth Stages .............................. 37 Figure 6. Precipitation Seasonal Distribution for 1982 and 1983 ..... 41 Figure 7. Temperature Seasonal Distribution for 1982 and 1983 ..... 42 Figure 8. Xerox of Slug Foliar Damage ............................ 46 Figure 9. Slu Damage in Field Corn Seasonal Distribution for 1982 an 1983 ............................................. 49 Figure 10. 1982 Seasonal Distribution of Slug Damage .............. 51 Figure 11. 1983 Correlation of Slug Damage Intensity with Slug Damage Incidence from Corn/Corn (0C) and Corn/Corn/Corn (C/C/C) Rotations ........................ 52 Figure 12. 1983 Regression of Slug Damage Incidence with Percent Ground Cover, Corn/Corn (C/C) and Corn/Corn/ Corn) Rotations ....................................... 59 Figure 13. 1982 European Corn Borer Foliar Damage Intensity Seasonal Distribution Statistics for Rotation .............. 80 Figure 14. 1982 Seasonal Distribution of Com Rootworm Adult Counts (#lplant) ....................................... 92 Figure 15. Flea, Beetle Foliar Dama e Incidence during the Mid-Late Whorl Stages or Tillage/Cover-Crop Treatment Comparisons in Alfalfa/Corn Rotation ......... 99 Figure 16. Flea Beetle Foliar Dama e Incidence during the Mid-Late Whorl Stages or Irrigated (II) and Non— irrigated (I0) Block Comparisons ....................... 100 xi INTRODUCTION In 1982, slugs Agriolimax reticulatus Miiller were observed to cause damage to field corn in some Crops and Soil Science Department experiments on the effects of tillage practice in field corn. Corn plants in some of the plots that had not been tilled at all suffered significant defoliation by the slugs, whereas in the adjacent tilled plots there was little damage by slugs. These obvious differences in slug damage among adjacent tillage treatments were the basis for the initiation of a cooperative project between Dr. Erickson of Crops and Soils, and Dr. Gage of Entomology, both of Michigan State University. As entomologists, we were primarily interested in assessing the effects of tillage on invertebrate pest damage and also on numberss of invertebrate pests and predators. We were secondarily interested in the effects of rotation, irrigation, and manure applications. Formalized research on alternatives to conventional tillage practices (collectively referred to as "conservation tillage") is motivated both by the need to halt erosion of topsoil, and by the need to decrease the inputs of fossil fuel in agriculture (Crosson 1981, Gebhardt et al. 1985, Phillips and Phillips 1984). Although conservation tillage requires less fossil fuel for tillage operations than does conventional tillage (Gebhardt et al. 1985, Crosson 1981, Muhtar, H.A. et al. 1982, Phillips and Phillips 1984), it is commonly accepted that conservation tillage requires greater fossil fuel inputs in the form of pesticides; particularly of herbicides, but also of insecticides (USDA 1975, Gregory and Musick 1976, Musick and Petty 1973, Crosson 1981, Phillips 1980). The assumption of a greater need for insecticides in conservation tillage production due to more frequent and more severe invertebrate pest attacks has generally been based on field observations, and rarely on formalized research. Many researchers, in fact, hold the opinion that invertebrate pest damage will, in fact, be less frequent and less severe in conservation tillage production than in conventional tillage production (Burges and Raw 1967, Walwork 1976, All and Gallaher 1977). The effect of various tillage practices on invertebrate pest damage ought to be examined separately for individual pest species in various climactic regions and for different crops (Wallwork 1976, Phillips and Phillips 1984, Cheshire and All 1979). In 1982, our investigations focused mainly on the identification of differences among the tillage treatments and on refinement of our sampling methods. In 1983, we established specific hypotheses based upon observations and differences chronicled in 1982. From observations that prompted the initiation of this investigation, and reports from the literature, we expected that slug damage would be higher in conservation tillage treat- ments, especially when large amounts of plant residues or manure were present. We were also interested in documenting if slug damage would be greater in irrigated treatments than non-irrigated treatments, assuming that the higher levels of moisture at the soil's surface would provide a good habitat for slugs. A second informal observation on pest damage in 1982 was that com plants in conservation tillage treatments had less foliar damage by the European corn borer. In general, it was expected that greater pest damage would be recorded in continuous corn than in rotated corn because the literature suggests that in locations where the same crop is grown year after year pests that are specific to a particular crop become established and the potential for pest outbreaks is greater (Pimentel 1960, Cox & Atkins 1981 , van Emden 1975). LITERATURE REVIEW This review considers the effects of various cultivation practices on invertebrates, with an emphasis on pest species. Described first are three common methods of tillage used in our study, and the definition of terms that are relevant to this thesis. The next section considers typical soil characteristics, comparing the extremes of tillage practices. This section will address the direct effects of soil Characteristics upon invertebrates as well as the influence of invertebrates upon the soil. Next, the indirect effects of tillage on invertebrates are considered, as exerted through tillage's influence on the plant physiology. Last is a review of the research involving the influence of tillage on the distribution and abundance of invertebrate pests and beneficial insects. The review does not consider micro-invertebrates (e.g. Protura, Collembola, Nematoda). The review will focus upon field corn production, and will emphasize production within the state of Michigan. Descriptions and Terminology In an agricultural system, cultural practices that reduce soil erosion or water loss when compared to ”conventional tillage” (e.g. moldboard plow) are collectively labeled ”conservation tillage" (Gebhardt 1985, Phillips and Phillips 1984, Crosson 1983). The federal Soil Erosion and Sedimentation Control Act of 1972 provides incentives for farmers in Michigan and throughout the United States to reduce losses of soil due to erosion through the implementation of conservation tillage measures (Tilmann and Mokma 1976). The reduction of erosion may be accomplished by adapting tillage operations and/or by managing the crop residues. Although the tillage process has often received the emphasis in programs to reduce soil erosion, 'residue management' is integral to these programs and is often used synonymously with conservation tillage. Other synonyms for conservation tillage are ”reduced-tillage”, ”minimum-tillage" and "no-tillage”. In our study, no-tillage, and variations of no-tillage comprised the majority of the tillage treatments. The term ‘no-tillage' (no-till) refers to a specific practice of soil preparation for the planting of seed. In a no-till system, the seeds are placed directly into the undisturbed soil with a special type of planter; a "direct-drill" planter. This implement ‘drills' the seed into unplowed soil at prescribed depths. Disturbance of the soil is restricted to a narrow strip (the "slot") in which the seeds are deposited. Fertilizer and/or herbicides can be applied at the same time that seeds are planted. Generally, only a single "pass" over the field (the physical process of a farming machine traversing a field) at planting time is required with the no-tillage method. Our study also consisted of a 'ConventionaI-tillage’ treatment; the moldboard plow. Conventional-tillage, in contrast to no-tillage, consists of two separate processes; "primary tillage" and ”secondary tillage". Together, these two processes require from three to five (or more) passes over the field and they consume more energy than any other farming activity (Gebhardt 1985). During the primary tillage process, the soil is processed with a moldboard plow. The moldboard plow is a implement equipped with a series of smooth, curved blades that completely overturn the soil to a prescribed depth. The plow leaves large clods of earth that are subsequently broken apart in a separate pass over the field by a ”disc" (an implement equipped with rows of vertical discs). During the secondary tillage process, one to several additional passes over the field may be made with an implement called a 'harrow'. The harrow further breaks up clumps of soil and grades it level. Next comes the planting operation which requires yet another pass over the field. Often, fertilizers, herbicides and/or insecticides are applied separately, requiring still more passes over the field. The high number of passes performed in conventional-tillage often results in soil compaction which reduces yields. Additionally, these practices exacerbate erosion by leaving soil exposed to rain and wind. Finally, conventional-tillage requires a significantly greater investment in fossil fuel energy (specifically, diesel fuel) than does no-tillage (Gebhardt 1985, Phillips and Phillips 1984, Crosson 1983, Robertson et al. 1979). In Michigan, the moldboard plow is the most commonly used primary tillage implement although Michigan farmers vary widely in the combination of tillage procedures that are currently used (Robertson et al. 1977, Robertson and Mokma 1979). There are a number of methods that lie in between the extremes of no- tillage and conventional-tillage. These methods also fall under the broad label of ‘conservation-tillage'. One such method used as a treatment in our study is called 'chisel-plowing'. The Chisel-plow is an implement with one to several series of curved tines (Chisels) is used during the primary tillage process. The Chisels break up the soil to a prescribed depth without completely inverting it. The chisel-plow can be adjusted to leave predetermined amounts of crop residues on the soil surface. Secondary tillage (harrowing) is often performed in conjunction with the chisel-plow method in one or more separate passes over the field. As with moldboard- plowing, the tillage operation in Chisel-plowing is separate from the seed- planting operation. In Michigan, especially in the southern part, farmers have increasingly substituted the chisel-plow for the moldboard plow (Robertson et al. 1979). Another method of reducing erosion used in our study that also falls under. the broad label of conservation-tillage is the use of cover-crops. In addition to the main crop, a separate crop may be planted in order to cover exposed soil (eg: rye, winter wheat, oats) and/or to add nitrogen to the soil (eg: alfalfa, clover, birdsfoot trefoil, vetch). In our study, cover-crops of rye, alfalfa, and crimson Clover were planted in the no-tillage treatments. Physical and Chemical Characteristics of Soil and Relationships to Invertebrate Organisms Our study did not involve testing for the effects of soil Characteristics on invertebrates. However, the physical and chemical Characteristics of soil are presented here to indicate factors that might contribute to an explanation of treatment differences. Physical and Chemical characteristics of soils that have been plowed differ from the Characteristics of soils that have not been plowed (conventional-tillage vs no-tillage). Compared with conventional-tillage, no; tillage has: 1) increased mechanical strength; 2) greater structural stability at the soil surface; 3) greater moisture holding capacity; 4) higher organic matter content; and 5) a larger mean-weight-diameter of structural aggregates (Cannell and Finney 1983). Conventional-tillage and no-tillage soils have different temperature and moisture regimes, different structure and orientation of pore systems. They also have different pHs' and different vertical and horizontal stratification of nutrients. All these soil ChuiaCterIStICS may vary with the soil type. Characteristics of the soil may influence the associated fauna both directly and indirectly. Direct influence can operate if a portion of an organism's life-cycle occurs within the soil. Indirect influences can operate through effects of a soil's condition upon the condition or appearance of host plants. Physical and chemical characteristics of the soil under various methods of tillage influence the organisms of the soil in various ways. Some pest problems may be aggravated, others alleviated and still others remain unchanged in conservation tillage systems (All and Gallaher 1976, Gregory and Musick1976). Crop residues provide shelter, moisture and extra living space for invertebrates. They are a source of over-wintering sites and of shelter from extreme weather conditions for both pests and beneficials. Residues are a food resource for invertebrates which process them into usable nutrients for crop plants. Soil moisture is a physical variable of the soil environment which is characterized by vertical and horizontal gradients. Soil moisture is distributed vertically in response to gravity and horizontally as a result of changes in topography (Amemiya 1968, Burrows 1963). Topography includes changes in elevation within a field (macrorelief) as well as features of the immediate soil surface layer (microrelief) (Burwell 1966). Soil moisture is a dynamic variable which fluctuates both diurnally, and with the seasonal in- fluence of precipitation (Amemiya 1968). Soil moisture at any given time is a function of numerous factors: 1. infiltration rate (the amount and rate of water absorption) , 2. run-off, 3. capillary water movement, 4. evapotranspiration (amount of water leaving the soil in a gaseous state) and 5. drainage (Cannell and Finney 1983). These factors are in turn dependent upon physical features of the soil substrate. The amount of of soil moisture is partially dependent upon soil texture (the proportion of sand/siIt/Clay), which becomes increasingly important in moisture limiting situations (Gardner 1944). When moisture is limited, the soil moisture decreases more rapidly at the size of soil particles increase (i.e. tiny Clay particles hold water more efficiently than do larger sand particles). When moisture is plentiful, soil moisture increases with increasing number and size of micro-pores and macro-pores that characterize the soil structure. The moisture content of a soil is often found to be higher under no— tillage, particularly in the upper two feet (half meter) (Amemiya 1968, Blevins 1971, Gauer 1982, Hill and Blevins 1973, Olson and Schoeberl 1970). This is attributed partially to greater infiltration and reduced evapotranspiration in no-till systems (Cannell and Finney 1983). Crop residues on the surface of the soil also enhance infiltration and limit evapotranspiration, thus playing an important part in the retention of moisture in a soil. In general, no-tillage soils have higher moisture content than do conventional-tillage soils, a difference that is greatest early in the growing season. As the crop canopy closes over the soil, evapotranspiration decreases, and differences among the different methods of tillage tend to decrease in significance (Cannell and Finney 1983, Gauer 1982). However, in some cases, higher moisture levels in no-tillage last throughout the growing season (Phillips and Phillips 1984). The moisture regime of soil is one of the factors intimately associated with the survival of invertebrate organisms that live both within and above the soil. The limits of tolerance to moisture limiting situations varies greatly with the life-stage of'the organism involved. Many insect eggs must absorb water to complete embryogenesis and hatch (Doane 1968, Krysan 1978, Mukerji and Gage 1978). The larval stage is especially critical for soil dwelling insects because of their generally soft and pliable cuticle. The cuticle allows for rapid growth of the larva, but also leaves the larva susceptible to desiccation and to abrasion by physical particles. Abrasion of the cuticle can negatively affect larval survival in moisture limiting situations (Wigglesworth 1944); Adults and pupae of insects, in contrast to the larvae, generally have a 10 tough exoskeleton which allows insects and other arthropods to survive under severely limiting moisture conditions, while still maintaining a favorable moisture balance with their environment. Adapting to moisture limiting situations, adult slugs estivate. Soil moisture indirectly affects invertebrates by affecting the vegetation (the host plant). Survival of European corn borer larvae residing within a corn plant can be adversely affected by drought conditions (Everly et al. 1979, Showers etal. 1978, Chiang 1961). Soil temperature and soil moisture are interacting factors that are in a state of flux. The amount of moisture in the soil influences the ability of the soil to conduct heat. Soil temperatures in no-tillage systems are generally higher during the winter and lower during the spring than in conventional- tillage (Phillips and Phillips 1984). Lower soil temperatures in no-tillage during the spring are partly due to larger amounts of plant residue at the soil surface (Gauer 1982). Lower spring temperatures in no-tillage soils are responsible for delayed germination and slower initial growth rate in field corn, but this factor does not greatly affect yields (Alessi and Power 1971). Conventional tillage soils are subject to more extreme fluctuations of temperature than are no-tillage soils. Soil temperature directly affects the developmental rate of soil dwelling organisms, particularly in the immature stages (Wigglesworth 1944). Indirectly, soil temperature affects soil fauna through its effect upon the growth pattern of the host plants (Branson 1981). European corn borers experience higher mortality under temperature- related climatic conditions such as drought (Showers et al. 1978). Another serious pest of field com, the corn rootworm (Diabrotica spp.) is exclusively soil dwelling throughout all of its immature stages, and therefore may be 11 particularly affected by soil temperatures. Corn rootworm egg hatch and rate of larval development in the Spring is, to a large extent, dependent upon soil temperature (Chiang and Sisson 1968). Soil bulk density is a characteristic that influences the movement of moisture and air and greatly affects the potential productivity of a given soil (Phillips and Phillips 1983). The impact of bulk density on productivity depends both upon seasonal changes and soil type. In lighter soils (e.g. sandy loam or loamy sand) during the spring, the bulk density of no-tillage soils is often greater than in conventional-tillage soils however this difference diminishes as the season progresses (Crosson 1983, Phillips and Phillips 1984, Gebhardt 1985). In more dense soils (e.g. silty-clay or clay) the bulk density of no-tillage remains greater than in conventional-tillage throughout the season (Cannell and Finney1983, Phillips and Phillips 1983). Bulk density may affect the 'rate of mobility' and the 'range of dispersal' of burrowing organisms such as the corn rootworms (Diabrotica spp.). The lower bulk density of conventional tillage could possibly allow the corn rootworm larvae to disperse more easily, and positively influence larval establishment on corn plants. Soils under no-tillage management have a higher 'porosity' than soils under conventional-tillage management, and the pores of the tillage methods also differ from each other in size and shape. No-tillage pores are contiguous and long lasting, whereas conventional-tillage pores are discontinuous and temporary. No-tillage pores are formed by by burrowing organisms such as earthworms, insects other arthropods, small mammals and plant roots. Conventional-tillage pores are formed when the soil is overturned during tillage and disappear as the season progresses (Cannell and Finney1983). 12 The greater the porosity of a soil, the greater the ability of the soil to absorb moisture and the higher the oxygen content of the soil atmosphere. Conversion of organic matter (humification process) into substances that are available for uptake by plants proceeds most efficiently and rapidly in the presence of adequate moisture and oxygen (Burges and Raw 1967, Wallwork 1976). The reduction in diversity and abundance of soil fauna associated with plowing can impair the conversion of organic matter into substances that are available for uptake by by plants (Burges and Raw 1967, Wallwork 1976). Nutrients and organic matter in no-tillage are concentrated in the upper few inches (centimeters) of soil. In contrast, conventional-tillage soil nutrients and organic matter are dispersed throughout the soil profile during the tillage process. The stratification of nutrients and organic matter Characteristic of no- tillage provides a concentration of food and a diversity of microhabitats for organisms that dwell in the upper layers of soils. In conventional-tillage the nutrients are dispersed, creating a homogenous environment which excludes those soil organisms with special requirements (Burges and Raw 1967, Wallwork 1976). In general, plowing a soil reduces the abundance and diversity of soil dwelling fauna (Burges and Raw 1967, Wallwork 1976). For example, certain shallow dwelling species of earthworms are excluded by plowing while other deep-burrowing species remain unaffected. Yet others, certain species of slugs and wireworms for example, may benefit from plowing through an increased surface area for breeding (Wallwork 1976). The positioning of soil nutrients together with bulk density can influence the growth pattern of corn plant roots (Barber 1971). As a result of the greater bulk density of no-tillage, primary corn roots do not penetrate as deeply as in conventional-tillage. Because of the shallow concentration of 13 nutrients in no-tillage, secondary corn roots spread out more in a larger diameter and to a shallower depth than in conventional-tillage. The growth pattern of corn roots might influence the initial establishment of soil pests such as corn rootworm larvae or alternatively it might influence the plant's ability to tolerate larval rootworm damage to the roots. Effects of Tillage Characteristics on Pests of Com Slugs are an erratic pest of corn that are rarely a problem in Michigan. However, in Central American countries they are serious pests (Saunders 1984). There are at least two species of slugs which attack corn in Michigan and both have been observed causing damage to field corn (Ruppel and Sharpe 1985). Moisture and temperature are two important factors which influence slug survival (Burenkov 1977). Soil texture, pH, and amount of organic matter at the soil surface may also influence the survival of these molluscs (Burges and Row 1967, Wallwork1976). Slugs have frequently been associated with no-tillage situations (Gregory and Musick 1976). Increased amounts of surface debris, increased temperatures and increased moisture probably interact to increase the abundance of these pests. Surface residues not only influence humidity at or just below the soil surface, but they also add to surface area available for retreat during the daytime, and may constitute a necessary environment for breeding (Gregory and Musick 1976). However, research in Great Britain shows that plowing the soil increases the vertical range for breeding slugs by allowing them to penetrate deeper into the soil than they normally would be able to travel (Wallwork 1976). There is some evidence that application of 14 manure attracts larger populations of slugs (Gregory and Musick 1976, Crosson 1983). The biology of the European corn borer, Ostrinia nubialis Hubner, would seem to lend itself to manipulation by the use of cultural methods of control. They remain as mature larvae within corn stalks and cobs throughout the winter. The practice of grinding up and burying residues from the previous year's crop as a control measure for corn borer is widely accepted by farmers, '...however this method was never economically evaluated.” (Pimentel 1973). This pest is polyphagous and can therefore utilize a large number of host plants in addition to corn, therefore it is not amenable to control using crop rotation or fallowing. Because the European corn borer larva lives inside the plant foremost of its life, it is directly affected by the physical condition of the plant. Recent work has demonstrated that in early stages of plant growth, borers on smaller corn plants have higher mortality than those on larger plants (Robinson 1978). This higher larval mortality in small corn plants than in large corn plants was found to be due to a secondary plant compound, Dimboa, which is found in higher concentrations in smaller corn plants (Reed et al. 1972, Robinson et al. 1977). Corn rootworms (Diabrotica longicornis (Say), Diabrotica barberi Smith and Lawrence, and Diabrotica virgifera Leconte) have been examined in greater detail than other pests with respect to the effects of tillage upon their biology and population dynamics. There are two major reasons for the interest in tillage effects on corn rootworms: first, they are the most important pest of corn in many agricultural regions, including Michigan. Second, all immature stages of corn rootworm are soil dwelling, therefore the tillage process has the potential to directly influence a major portion of the rootworm's life-cycle. 15 There are a number of soil related factors which influence oviposition by com rootworms. Ovipositing females of corn rootworms are attracted to moisture and plant residues, to loosened or disturbed soil as well as to cracks in the surface of the soil where their eggs are often aggregated (Chiang 1973, Kirk et al.1968). Weeds can also influence the positioning of corn rootworm eggs. Green and yellow foxtail are preferred oviposition sites and may serve as alternate hosts for overwintering and larval development (Branson and Ortman 1967). In no-tillage systems there is a greater problem with grass weeds such as foxtail, which potentially increases the number of oviposition sites for the rootworms. In a no—tillage situation, eggs of the corn rootworm are concentrated at the base of the corn plant, but in conventional-tillage the eggs are dispersed, both horizontally and vertically (Pruess, Weekman and Somerhalder 1968). Fall plowing exposes the overwintering eggs to extreme temperatures in winter and it has been proposed that this practice can reduce infestation levels (Chiang 1973). Spring plowing may be more effective in reducing populations when winter precipitation is minimal, partly because the diapausing eggs require water to complete development (Krysan 1978), and partly because under low moisture conditions eggs are more susceptible to desiccation by abrasion of the Chorion (egg surface) that occurs during the plowing process (Chiang 1973). In soils with a lighter texture the effect of plowing may not be significant, as less abrasion of the chorion's surface occurs in these soils (Chiang 1973). Soil moisture and soil texture appear to interact in their effect upon corn rootworm larval mortality. Abrasion of larvae by soil particles occurs normally, but in moisture limiting situations the potential for desiccation is 16 enhanced (Wigglesworth 1944). This synergy is more striking in sandier soils. As the Clay content of soils increase, so does corn rootworm larval survival under moisture limiting situations (Turpin and Peters 1971). Soil moisture also interacts with soil temperature to influence corn rootworm larval mortality. When moisture is limited, larval mortality is higher under constant temperatures; varying the temperature during larval development results in greater numbers of corn rootworm survivors (Turpin and Peters 1971). Higher larval mortality under manure mulches and in the presence of plant residues has been recorded (Chiang 1973), and predation by higher populations of mites has been suggested as a mechanism for this striking increase in mortality. With respect to rootworm populations there is not yet convincing evidence to support a hypothesis which shows an advantage of one tillage system over another. The distribution of rootworm eggs in the field is highly clumped and extremely variable, and it is extremely difficult to make valid comparisons of tillage systems. However, one theory predicts that a monophagous pest (such as the corn rootworm) will have greater mortality in a more complex environment (Risch 1983). Because the no-tillage environment is more complex than the conventional-tillage environment, according to this theory there should be less frequent and less severe outbreaks of corn rootworm in no-till systems. No-tillage treatments in one study required four times as many eggs to obtain infestation levels comparable to those of conventional-tillage treatments (Gregory and Musick 1976). Chiang (1973) noted a similar pattern of reduced infestation and damage to corn roots by com rootworms in no-tillage compared with conventional-tillage. 17 A method of control of rootworms under continuous corn that is unique to no-tillage is the practice of planting seed between the rows of the previous year (Chiang 1973). Because eggs are aggregated at the base of corn plants (Chiang 1973, Foster 1979) this method requires the larvae to travel longer distances which effectively reduces damage by influencing larval mortality. The first recorded instance of no-tillage having an adverse effect upon an insect pest was found in the lesser cornstalk borer, Elasmopalpus Iignosellus (Zeller). This is a major pest of many legume and grass crops, particularly in southern states. Infestation levels were dramatically reduced in no-tillage corn compared to the levels in conventional-tillage (All and Gallaher 1977). These differences in infestation levels were associated with higher soil moisture levels in no-tillage; irrigation also resulted in lower levels of infestation (All and Gallaher 1977). Cheshire and All (1979) identified a second factor that was involved in this phenomenon. They discovered that the lesser cornstalk borer is a facultative detritivore, and that the presence of a mulch on the surface of the no-tillage treatments provided an alternative food source for the larvae of this pest effectively eliminating their dependence upon the corn plant for food. Armyworm and cutworm infestations have been induced by specific combinations of cultural practices. Female black cutworm moths are attracted to crop residues, especially soybean residues, for oviposition (Gregory and Musick 1976, Johnson unpublished data 1982). The larval stages of these lepidopterans ”prefer" the structural characteristics of plowed soils (Wallwork 1976). The manipulation of weeds and cover-crops can influence the distribution of these polyphagous pests. Herbicide applications can effectively remove weeds as a food source for cutworms after which they are forced to turn to the crop itself (Gregory and Musick 18 1976). Cool, wet springs may also increase the probability of outbreaks of this pest (Gregory and Musick 1976, Johnson unpublished data 1982). If tempera- ture and moisture are the main factors that influence this observation, then the higher moisture and lower temperature of no-till soils could aggravate the overall abundance of this these pests. Wireworms (Elateridae) are an occasional pest of corn in Michigan. The greatest part of the life-cycle of these insects is spent in the soil. The egg stage is particularly influenced by temperature and moisture. An increase in the former accelerates the rate of water absorption and embryonic development (Doane 1968, Doane 1969). Not suprisingly, female wireworms are attracted to moist soil for oviposition (Doane 1968). Gregory and Musick (1976) hypothesized that wireworm populations would increase in no-till situations, and some members of Elateridae are more populous in unplowed than in plowed soils (Wallwork, 1976). However, certain root-feeding species of wireworms thrive under conventional-tillage conditions (Wallwork 1976). Upon plowing, organic debris which many Elaterids use for food becomes widely dispersed and is rendered unavailable. It is at this point when wireworms may become pests as they switch their feeding to crop roots; this is also true of the seed-corn beetle Stenolophus Iecontei (Chaudoir), a detritivorous member of the family Carabidae that will also feed upon the seeds of corn when other food is unavailable. The grasshopper egg stage is influenced by moisture and temperature (Mukerji and Gage 1978). In strip-farmed fields it was shown that the border between plowed and unplowed soiI was important habitat for oviposition; five times more eggs were detected in the plowed portions than in the unplowed portions (York 1951). 19 Plowing the soil interacts with soil insecticides to reduce abundances of predator populations (Dritschilo and Erwin 1982, Dritschilo and Wanner 1980, Wallwork 1976). The restricted breeding seasons and long life-cycles of many of these predators impede a quick recovery of the population from the traumatic impact of plowing and/or treatment with soil insecticides. Ground beetles are predacious beetles whose entire life-cycle is spent in close association with the soil. Most comparisons of predators between no-tillage and conventional-tillage have focused upon this abundant group of insects in the search for effective biological-control organisms. Ground beetle adults may benefit from the presence of plant residues that provide shelter and living space (Dritschilo and Erwin 1982, Dritschilo and Wanner 1982, Lavigne and Campion 1978). One study of surface dwelling arthropods in no-tillage, conventional-tillage and old-field habitats revealed a trend in abundance of ground beetle adults. No-tillage had the highest number of ground beetles and the greatest number of species, conventional-tillage had the lowest number of ground beetles and the least number of species, and the old-field habitat was intermediate in number of beetles and number of species (Blumberg and Crossely1983). MATERIALS AND METHODS Study Location and Site Description The study took place at the Michigan State University WK Kellogg Biological Station (KBS) in Hickory Corners, Michigan (Figure 1). There were two study locations (Figure 2). Both locations had soil that was composed of Kalamazoo sandy loam, with localized areas of Osthemo loamy sand. The topography was generally level, although the western-most location sus- tained a slope of approximately fifteen degrees in some parts. Both locations had been planted to alfalfa for at least tWO years prior to being used in these experiments. Experimental Design In 1982 and 1983, experiments were designed to investigate the effect of tillage methods, irrigation, manure application and crop rotation on the production and yield of field corn. In 1982, there were two rotational sequences; an Alfalfa/Corn (A/C) rotation at location A (Figure 3) and a Corn/Corn (C/C) rotation at location 8 (Figure 4). In 1983, there were three rotational sequences; an Alfalfa/Corn (A/C) rotation, and a Corn/Corn (C/C) rotation at location A (Figure 3) and a Corn/Corn/Corn (C/C/C) rotation at location B (Figure 4). Each rotation was divided into four blocks: 1. non-irrigated (l0), non- manured (M0); 2. non-irrigated (l0), manured (M1); 3. irrigated (I1), non- manured (MO); and 4. irrigated (l1), manured (M1). There were four repetitions of each block per rotation. 20 21 £35 £33 tea 85623. 31:52:38.... _8_mo_o_m 30:8. 2.3 Co n22 .— 952... 3021 do .5021... do 83:35. «3]. l I. :3 " 32.-2 1.6.1:! 81351- 06 EDA-.4 139:. 3. 33.3. R l '3 3.... ll II. M ..u. .I. . a . “a. / 9-3-0ng .... u n .l.. m . 002.255. u . .. .9.. (I. limit-Iv... o unison-ob} m. In I. .li-sl-voe. 553.1! m. .S . n be I. rho m ._ :35 3C8 " o. . I a: .8: 1:33! 3410...: 132:. . 2:. . 0: 2.40.? o / .. .- . I..- M .2115: 3.53531 w,, :2 a *; PI v n. m m . . au _ 4 M .1}. H IIECU Kg m as: w CI 5.3 up; 5 / .m a: 5.9.9.: .. .5130 :35! . 9. 553.3 ..- 20:5—0 4(0_UO..°_ I>l13§5 In; Jami-1.; doi:1- . K . H1... IAV moon D ID - 0.0 m" 7 2: 9 xammn E 1 I II .— souvu amt-49 0A gnu “www- in” .I I! .0... 530 mg :15 $9M“! “MA 01 \Dmsmoj VS . _ G. . mtg-((10 ¢-—--— sou-isw )1 22 , »,(I a In. . .Nk- a L :m G '.r‘ . ~ ,4“... '. ia! Photograph of W.K. Kellogg Biological Station showing Plot Locations. Figure 2. Aer AIC= C/C = m III 23 Not present Not present NC NC CP NT PL NA NC NR NT NR PL NA NC CP Alfalfa/Corn _ Corn/Corn PLOT SIZE - 50 FT x 30 FT Moldboard Plow Chisel Plow No-till No-till R e Cover-crop No-till C over Cover-crop NO'tlII Alfalfa Cover-crop (I1) = Irrigated cp (M1 + II) = Irrigated and Manured NT (M1) = Manured NC (IO + M0) = Not irrigated or Manured NA 2 23 II II II II II II Figure 3. 1982 and 1983 Plot Maps. location A. 24 crop fit: r////////Il w W. m w mm. mm I////é///// mu m L A I l/////// a... I. I w I II 3 l///////// 3:! I //////// //////// I////// ///////. //////// PL CP NR NA NT NT PL CP NA NR NT CP PL NR NA Figure 4. 1982 and 1983 Plot Maps, location B. 25 The blocks were further subdivided into tillage/cover-crop treatments. The six basic tillage/cover-crop treatments were: Moldboard plow (PL), chisel plow (CP), no-till (NT), no-till with an alfalfa cover-crop (NA), no-till with a clever cover-crop (NC), and no-till with a rye cover-crop (NR). The size of the plots was different for each of the two locations. At location A (Figure 3) the plot size was thirty feet by fifty feet, and at location 8 (Figure 4) plot size was fifteen feet by fifty-five feet. Site Management The Crops and Soils Science Department designed, implemented and maintained the study plots. Implementation and maintenance included all aspects of production; from soil preparation and planting, through harvest of corn and drying. The Crops and Soils researchers collected data on soil temperature, soil moisture, percent ground cover and corn yield. Management inputs were performed by the Crops and Soils researchers. Fertilizer applications dates, rates and materials are reported in Table 1. Herbicide application dates, rates, materials and treatments are reported in Table 2. Insecticide application dates, rates, and materials are reported in Table 3. Tillage operations, dates, and type of machinery used are reported in Table 4. Planting dates, varieties, and methods of planting are reported in Table 5 (field corn) and Table 6 (cover-crops). Cover-crops varied from year to year and from rotation to rotation (Table 7). In the 1982 and 1983 Alfalfa/Corn rotations, the no-till Clover (NC) treatment was tilled in an identical manner to the moldboard plow (PL) treatment. After tillage, clover seed for the cover-crop was then broadcast- planted onto the NC treatment. In 1983, the no-till alfalfa (NA) and no-till Clover (NC) treatments in the Corn/Corn/Corn (C/C/C) rotation had extremely 26 Table 1. Fertilizer Applications. Rate Year Rotation Date Fertilizer Treatment Block lbs/a kg/ha 1982 NC 4/21 0-0-60 250 280 all (MO) blocks * A/C 4/21 0-0-60 120 135 all (M1)blocks * NC 5/3 10-40-10 100 112 all blocks @ NC 6/1 ammonium 50 56 all blocks * nitrate C/C 4/21 0-0-60 250 280 all blocks * 0C 58 10-40-10 120 135 all (MO)blocks@ C/C 6/10 ammonium 50 56 all blocks * nitrate 1983 AC 5/13 340-10 100 112 all blocks @ (2% ZN) C/C 5/12 0-0-60 85 95 (I0/MO)& . (l1)blocks * C/C 5/13 8-40-10 100 112 all blocks @ (2% ZN) CIC/C 4/27 28% liquid zoo~ 224 all blocks @* nitrogen C/C/C 5/11 8-40-10 100 112 all blocks @ (2% ZN) * broadcast @ banded at planting @* SOHigro A/C Alfalfa/Corn Rotation CIC Corn/Corn Rotation CIC/C Corn/CornICorn Rotation (MO) Non-manured (M1) ('0) ('1) Menu red Non-irrigated Irrigated 27 9: .362 u 22 .362 I 32 8:83. 582.8228 n 800 5.68.3.2 u 82 26:95 I 8 8:23. 582:8 u 88 3.2.5.262 I <2 26: 282222 I : 8:32. 583232 n 82 .__o 8: 53>. 22.32 mm. 8.3 .3828 888 22.32 3 .3 8.3". on: 888 82.2 R. 83 £8. 9: 82 8.: .33. RN 8:: 888 22.32 €- 03 .5328 mm 82 22.8.: 3. 8.~ 8.53m 888 22.32 3.. 8m 92.: em 82. 8-: 3.. 09m 0:2 on 82 22.32 mm. 8.3 .5828 22m 88 22.32 8. 8.3 8:2: 8.3 oz. 22.32 3. 2; ass 33 oo 8.: 3. 8.~ 2:98 em 82 8.: 3. 09m SE 3 :3. 88 oz.<2 3m. 8.. £8. 9: 82 22.32 3. 8.~ 8:98 32 88 2.2.32 mm. 8.3 .5328 as 82 8.: 3. oo.~ 8:25 Em Up <2 mm. 3.2 as: an 82 4.2.32 3.. com 8-882 32 up 22.32 3.3 gm 233 Q... 82 8.: 3 .3 SM 95 2m oz. 22.32 mm. 8.3 8398 3m 82 8.: £- 84. .3553... 83m 82 22.32 E. oo.~ 2:93 38 82 <2 3. 2.3 8:28 mm 82 8.: G3. 8.~ 8.53m in 82 22.32 R. 8.3 8:23 em 82 22.328 3.3 com 3.882 mg 8).. 8-: 83. SN 8:22... em 82 oz 83. 8a 8863 oz... 82 2282-328 mm. 8.3 8330-3.-N m3 oz. 3383583... as: (Do 3:258..— mfimv. <2... aocuto>ou 33685381 2mm cozfiom a03u¢w>ou 2555: 335 c0220”. 88:: 32 82.3 $3 288:2? 8655: 83 2233282 865;: $3 6:038:23? 2683.8: .~ 233. 28 c0233. Eou\c._ou\c.ou c0233. 50258 3.23802 583:3? .923 02.3 :8 3:: 3823 $22 of :56: .35 wrote :56: .Cz. ___3-oc - .obcoo as: 32 .© 9.8.: =: .. 85:2: 3: 82:8 8: 8.: 2: 32:26 E: 888 .. 22:: 33 8.3 5.28 m :2. ob .. 85:2: 3.... 82:8 8: 8.: 68 389;: 33 Ho .. 22:: 33 8.3 5.28 E oi .. 85:2: 3: 85:8 8.: 8: 88 82:35 33 82 8:3 I© 22:: 8.3 8.3 :38 we: 88 © 22:3 8.3 8.3 :38 :8 88 I 85:2: 3: 82:8 3.: on: of :823 8 OD .. 85:2: 3: 82:8 3.: 8.: of :323 mm o2 ~23 3:3 <2: 8052). 83288:. 3.8 cozfiom 23> 33. . 2:233:32: 38:83:. .m 332. ODD UD U2 29 c0333. EouEBuEBu UDD 26.: .828 u 8 85:8: 5:258 I oo 26.: 22:82.22 n : 853:: 5:22.32 I o2 30£m_c_u_-flcm._ $035.0 Lt; mmmzfi >3mUCOumm AU amp—u 62.5 ”EU cm>mm :Om mOucm_0 £33 303 _wm_r_u Em UGO :wr—flciibcm... mOucw_U .E 53> 802:: 2:28:32: :85 .820 omfi .30.: 8320339: .flm ODD 8.: 2:225:28: 525 825 2:2:88 :8 oo 8 22:: =8 8822 52s 26.: .822 5: ob : 26.: 22:82.9: 3: oo 8.: 2:225:28: 53, 825 2:2:88 2m o2 8 22:: =8 88:6 5:5 26.: em o2 oz 82822528: 5;) 285.3 2:: 26.: 22:22.8: :m o2 : 32:28:22.3 Re 9: 8:3 8 8:: :22 2:: 26.: :82: :2: oo : 8:: :22 2:: 26.: 22:82.22 :2: oo 8 8:: 8.2 2:: 2.2: .822 :2: o2 oz .: 8:: :22 2:: 26.: 25:22.9: :3 oz. ~23 3:25:83. ommzfi 2052—2 32:: 8.20 33232.62 58> 8:032:20 mom...» .2 :32... 30 Table 5. Field Corn (gfi mays L.) Variety and Planting Dates.1 Year Rotation Date 1982 NC 5/3 NC 5/3 1983 NC 5/13 CIC 5/13 CIC/C 5/11 NC = Alfalfa/Corn Rotation CIC = Corn/Corn Rotation CIC/C = Corn/Corn/Corn Rotation 1Field Corn - Great Lakes Hybrid 5922 [(29,300 seeds/A ~ 64,600 seeds/ha) all no-till treatments were planted with the Buffalo no-till slot planter. 31 Table 6. Cover-Crop Varieties and Planting Dates. Year Rotation Date Cover-Crop Variety IE3: Method 1982 NC 8131/81 Wheeler rye hand-broadcast A/C 515/82 Mammoth red clover hand-broadcast C/C 8131/81 Wheeler rye hand-broadcast C/C 9/15/81 Canadian Mammoth 12 hand-broadcast red clover C/C 3129182 Canadian Mammoth 12 hand-broadcast red clover C/C 4120182 Canadian Mammoth 12 hand-broadcast red clover 1983 NC 917182 Wheeler rye hand-broadcast A/C 5110/83 Candian Mammoth 12 no-till Moore red clover * uni—drill C/C 9/10/82 Wheeler rye hand-broadcast C/C 5110/83 Canadian mammoth 12 no-till Moore red clover * ‘ uni-drill C/C/C 9/10/82 Wheeler rye hand-broadcast *reseeded to ensure a complete cover. NC = Alfalfa/Corn Rotation CIC = Corn/Corn Rotation CIC/C = Corn/Corn/Corn Rotation 32 Table 7. 1982 and 1983 Tillage Treatments by Rotation. Year Rotation Tillage Treatments 1982 Alfalfa/Corn (A/C) Moldboard Plow (PL) Chisel Plow (CP) No-till (NT) No-till Alfalfa (NA) No-till Clover (NC) Corn/Corn (CIC) Moldboard Plow (PL) Chisel Plow (CP) No-till (NT) No-till Alfalfa (NA) No-till Rye (NR) Alfalfa/Corn (A/C) Moldboard Plow (PL) 1983 Chisel Plow (CP) No-till (NT) No-till Alfalfa (NA) No-till Clover (NC) . No-till Rye (NR) Corn/Corn (C/C) Moldboard Plow (PL) Chisel Plow (CP) No-till (NT) No—till Alfalfa (NA) No-till Clover (NC) No-till Rye (NR) Corn/Corn/Corn (C/C/C) Moldboard Plow (PL) Chisel Plow (CP) No-till (NT) No-till Alfalfa (NA) No-till Clover (NC) No-till Rye (NR) 33 poor stands, and were eventually removed from the experiment by mowing during early August. Pest data for these treatments through July will be discussed in this thesis. Irrigation was performed using a solid set sprinkler system with 9 foot (3 meter) risers. In 1982, the irrigated (I1) block in the Corn/Corn (CIC) rotation was irrigated during July and August. Technical difficulties in 1982 prevented irrigation of the Alfalfa/Corn (A/C) rotation until August, at which time only two of its repetitionswere irrigated. In 1983 plots were irrigated from July through August. Manure was applied to test its effects as a compliment to (not as a substitute for) commercial fertilizer. Manure was supplied by the dairy facility at the Kellogg Biological Station. The application rate was approximately ten tons per acre (ie: 3.6 metric tons per hectare). It was applied one month before planting. In addition to manure, commercial fertilizer was also applied to the manured (M1) blocks, in amounts that were intended to equalize the total soil nitrogen with that of the non-manured (MO) blocks. Further details about the measurements and observations made by the Crop and Soil Science team are provided in Energy Integrated Farm Systems (ElFS) Reports #8, #38 and # 40. Invertebrate Pest Sampling Methodology In 1982 and 1983 the experiments were surveyed to determine damage and numbers of Invertebrate pests on the corn plants. 1982 and 1983 data were collected using different sample units, therefore the results are not directly comparable. Because of this the 1982 results will always be presented prior to, and separately from the 1983 results. 34 To avoid edge effects in the surveys the outer two to three rows of corn and approximately five feet of border at the cross-row edges were not surveyed. Survey sample units were selected by pacing a randomly selected number of paces along a row of com. A number from a double-digit random numbers table was chosen. The digit in the "ten" place indicated the number of full-paces (two steps); digit in the “ones” place indicated the number of half-paces (one step). For example, the random number 86 indicated 8 full- paces and 6 half—paces. If the end of a row was reached, the observer would cross over two rows (skipping a row) and continue to pace in the opposite direction. When the designated number of paces had been taken, the plant closest to the observer's right foot was the first in a set of five adjacent plants to be sampled. This process was repeated until three sets, each composed of five plants, had been surveyed in a plot. Descriptions of pests and pest damage were obtained from the Cooperative Crop Monitoring System Handbook (CCMS, 1982 8 1983). Qualitative assessments of damage to corn plants were dependent upon the pest and the plant stage. Major descriptive characteristics of invertebrate damage included: 1. Damage that removed the entire plant from production (ie; number of plants killed, wilted, stem broken off below the ear);2. Damage to foliage (ie; shredding, holes, mining, eaten areas); 3. Damage to stems (ie; exit holes from borers); 4. Damage to tassels, silks and seeds and cobs. Indirect assessment of pest organisms were made by surveying pest damage to the corn plant. Quantitative assessments of pest damage were recorded either as "damage intensity" or "damage incidence" (Walker 1983, Chiarappa 1971). Damage intensity, was defined as the amount of damage to a particular plant (degree of attack), and was assessed using a rating scale 35 (Walker 1981) (Table 8). Damage incidence was defined as the number of plants with damage (Walker 1981, Chiarappa 1971)). Crop growth stage charts were used to identify the morphological and physiological stages of the plant in 1982 and 1983. These descriptive tables were obtained from the Cooperative Crop Monitoring Handbook. The corn phenology system used by CCMS changed from 1982 to 1983 to conform to the development of the new Hanway phenology system (Aldrich et al. 1975); 1982 crop growth stages (Figure 5) were more general than the 1983 crop growth stages (Table 9). In 1982 all plots were sampled on a weekly basis (Table 10) beginning on July 7. The survey sample unit was a set of five adjacent corn plants, rated for damage as a single unit (CCMS Handbook 1982 & 1983). Three sets of five adjacent corn plants were sampled per plot for a total of three sample units per plot. In 1983, surveys were structured to coincide with the activities of three major invertebrate pests: Agriolimax reticulatus Muller (grey garden slug), Ostrinia nubilalis (European corn borer) and Diabrotica spp. (corn rootworms). Peak activities of these three pests were determined by combining information from a number of sources: 1. surveys from the 1982 field season, 2. preliminary field observations, and 3. field crop reports from the Pest Alerts newsletters of the Cooperative Crop Monitoring System (CCMS). Dates of 1983 surveys are given in Table 10. The 1982 analyses did not detect differences in invertebrate numbers or pest damage among tillage/cover-crop treatments. This contradicted some of our field observations. To increase our precision in 1983 we modified the survey sample unit and the intensity rating scale (Table 8). In 1983, the survey 36 Table 8 . Damage intensity ratings for invertebrates. Damage Intensity Rating 5 I C3 e 1 1982 Individualglaaant sam le S-plant sample unita “Rub p 0 None None (%) 1 Trace Trace (25%) 2 Light Light (S-9%) 3 Medium Medium(10-29%) 4 Heavy Heavy (30-79%) 5 Extreme Extreme (BO-100%) aFive adjacent plants rated as a single unit (3 sample units/plot). bOne plant rated individually (15 plants/plot). 37 Growth Stages Of Corn Stage or Approximate time Numerical alter emergence Gropth type Diagnostic character designation from the soil I’ve-emergence Seed planted 7 0 Emergence Coleoptlle above soil 0.1 0 Two-leaved 2 leaves fully open 0.5 1 week Early whorl 4 to 6 leaves fully emerged 1 2 to 3 weeks Mid-whorl 8 to 10 leaves fully emerged 2 4 to 5 weeks Late when 12 to 14 leaves fully emerged 3 6 to 7 weeks Tassel 16 leaves fully emerged 4 6 weeks Silk Silks emerging. pollen shedding 5.0 66 days Plant pollinated: silks green to brown 5.5 Maturity Brown silk. cob lull sized. blister stage 6 12 days after silklng Kernels in “soft dough” - 7 24 days after sillung Few kernels with dents. embryos developing 8 36 days after silkmg All kernels with dents 9 48 days after silking Grain mature and drying 10 60 days after silking GROWTH STAGES or CORN ”mflfim?" or A - «a um i - sell-u. om c - rem ears. was i - can: t . mm P - Slu s - co in m 1r 1 STAB! l " STAG! no: N 0.1 m II {P o l 2 J 0 A‘ _ O * WI ' _ mu III. a; nu mum mm. anon new mom moat-u» moan mar-m mammals. i. neesru. a soul-urn comm my on up «nu. mm. mm as In: max. min none. to m 11.1. “9“ “In?! a MN I msrrom SWNIIM: (mil mm. we. M W I Slu! MI 70 9.13m 8?“ a». I. new II '28? Iii? 1. it" w em '1”? l. w. 01.1 an arm .11. ”mus: mam 3:, “ml um Hum u-nm um Seedling Early Whorl Mid-late Whorl Early Reproductive Late Reproductive Figure 5. 1982 Crop Growth Stages. 38 Table 9. 1983 Corn Growth Stages 8: CCMS Codes.1 Life Stage Code Stage Description Seedling Stage 01 v0 - Emergence 02 v1 - First leaf full emerged 03 v2 - Second leaf ully emerged 04 v3 - Third leaf fully emerged Early Whorl Stage 05 v4 - Fourth leaf fully emerged 06 v5 - Fifth leaf fully emerged 07 v6 - Sixth leaf full emerged 08 v7 - Seventh leaf ully emerged 09 v8 - Eighth leaf fully emerged Mid-Late Whorl Stage 10 v9 - Ninth leaf fully emerged 11 v10 -Tenth leaf full emerged 12 v11 - Eleventh leaf ully emerged 13 v12 -Twelveth leaf fully emerged 14 v13 -Thirteenth leaf fully emerged 15 v14 - Fourteenth leaf ful y emerged 16 v15 - Fifteenth leaf fully emerged 17 v16 —Sixteenth leaf full emerged 18 v17 -Seventeenth leaf ully emerged Early Reproductive 19 v18 - Eighteenth leaf fully emerged Stages 20 v19 - Nineteenth leaf fully emerged 21 v20 -Twentieth leaf fully emerged 22 vt -Tassle fully emerged 23 r1 -Silks visible Late Reproductive 24 r2 - Blister stage Stages 25 r3 - Milk stage 26 r4 - Dough stage 27 r5 - Dent stage 28 r6 - Physiological maturity (black layer present) 1From CCMS manual (1983). 39 c0333. ccou\c:ou\c:ou u uDD 828:: 582:8 u 08 82:8: 583.32 u 02 @2838an 32 m- boom UD u\< 38:22:82.5 m~-m~ :3 08 0.4 88:228. 8:. 3.2%: 088 0.0 02 88:29:82.6 :2: :3. 08 02 33038032 3:3 m~-m— 9.4 UD u\< 3:83.23: 28.35:. 5m 93 DD u\< 2::; 8:. 5:: :2 088 88:228. 2:: m..~ :3... 08 02 2::; 82-2.2 :78 22 0...: 02 2238:. :~-:~ 22 08 0.4. 2232.8 :~-:~ 2:. 088 2::; 82-2.8 8-..: :3 oo 02 2::; 2::: 3-2 :5: 088 08 02 2232.8 3-2 :2 ob 02 9:288 m: 8s. 088 2232.8 :A :2 ob 02 omfim nob 3mm cozmoom 3:3 :00 3:0 cot-Sou flavogum .623 mm? Ezoozom >o>5m wmmp 83282: 82:: $2 2:: ~22 .8 2::: 40 sample unit was changed to an individual corn plant. As in 1982, three sets of five adjacent corn plants were sampled in each plot for a total sample size of 15 sample units per plot (as compared with three sample units per plot in 1982). The 1983 foliar damage intensity rating was modified to reflect the percentage of a corn plant's foliage affected by invertebrate pests. Numbers of invertebrates per plant were counted and recorded in both 1982 and 1983. The seasonal distribution of precipitation and temperature differed fro 1982 to 1983. The seasonal distribution of precipitation by crop stage is shown in Figure 6. The seasonal distribution of temperature is shown in Figure 7. The 1982 data was entered from field forms onto a microcomputer and later transferred to a minicomputer where it was written onto magnetic tape. The tape was loaded into INGRES database management system on the VAX/780 computer at the Kellogg Biological Station. Invertebrate numbers and intensity data collected in 1982 was summarized into tables of means. The means tables were examined visually for trends. Major trends in 1982 were then examined using a chi-square analysis. In 1983, data was entered directly into INGRES using QBF (Query by Forms). Initial data processing and analysis was done at KBS using PSTAT and BMDP statistical programs. The final analysis was done at the MSU entomology department using the SAS statistical program. In 1983, data was first characterized by frequency distributions and skewness and kurtosis indicators. Transformations were performed where indicated. Next data was analysed by the analysis of variance procedure (ANOVA) using the model shown in Table 11 (Steel and Torrie, 1980; Lopez and Lopez, 1984). Data was also analyzed using the distribution-free Kruskal-Wallis procedure (Steel 8- Torrie, 1980; Jones, 1984). Multiple comparisons of treatment means were 41 .mwmw tcm Nae .2 zeta—tuna .mCOnmom cozmzatoi .c 2:9“. 3.83533. 8.3 35323:. 2.3 _:o;>> 32.25. 29.3 2.3 9:233 a _ _ _ o e e lo \ ’ \ eee Ie(e o \o o: l I m e . ee e 6:; . \ . . I. 523382: .\ . z - a \ ‘eee-eee-eee eeeeeae’aerC Nwm— / :1 m 42 .mme Ucm NwGP 50w C033n=3£0 _MCOmmwm whaamwaF—wh .h 9.36: oztsooaom 8.2.. 81838231 >23 _:o:>> 32-2.2 _:o;>> 35m 9583 2 q q q o Co. 8.32595.— 43 only performed when significance was indicated by the ANOVA and Kruskal- Wallis tests). Tukey's w test was chosen because it (Steel and Torrie, 1980; Jones, 1984) protects the type-1 error rate when comparing large numbers of means as was sometimes necessary in this study when interactions in the ANOVA were significant. In some cases the ANOVA detected differences while Tukey's did not. In these cases, a less conservative test, the SNK mul- tiple comparison test, was employed. Slug Damage Measurements In 1982, slug damage intensity was assessed as described in the general sampling methodology. In 1983, both slug damage intensity and slug damage incidence were assessed, also asdescribed in the general sampling methodology. As an additional measure of slug damage, in 1983 the percent of the total corn plant leaf surface area damaged by slugs" was quantified in a subset of the tillage/cover-crop treatments. The assessment was carried out during the early whorl stages of com, the period of highest levels of slug damage. Ordinarily, destructive sampling of corn plants was not permissible because of the potential impact upon yield results. However, in 1983 there was an overseeding of corn in the Corn/Corn/Corn (CIC/C) rotation. We used this opportunity to further quantify slug damage intensity. The percent of total leaf area damaged by slugs was compared for the Corn/Corn/Corn (CIC/C) rotation in non-irrigated (I0), non-manured (M0) blocks for til- lage/cover-crop treatments PL, CP, NT, and NR. The no-till clover (NC), had few corn plants due to poor emergence, and therefore this treatment was not included in the comparison. The leaf area damage evaluation took place in the early whorl stages of corn when slug damage was highest. .38— 2.:o» 2:: 33m. :98: 8.: £3-53 9t :2 _ooo_2~ .239 8:80 2:: 3:52 :93: 0.003 53.23 or: .o. Enos: To: 2 -.<._.O._. 73:: 4.3.0... 28:72:: 2-05-252 3 :25 323. x 95:22 x :ozmmt: 285-22: 28.2-25-3 A2. 3:: om2E x 93:22 x cos-oat: 2-92-2. 8:...» x 8:::5. 285-8 8::: x 8:::5. 3-05-3 32:... x :ofimmt: 20:73 32.:- x c259... To a: om2E. To R: om2E 2.25.32... 3 2::: 28:75:. 2: :25 2-82-2 23:22 x .55ng 2-25:. 8:::5. x 52:92. 2-2.2-2: 3. 5:: Tn av 23:22 7: 8V o5E22 2-3 2-: A3 :25 3-3 2-: E :95 7: 2. 52:9... 7: .3 82:9... 7: 2:25:32 9.00:. T: Acct-zoom: $803 ”5 853 “5 850m 2:28 2:... 2.3-2.3 298: :22: 2.3-2.3 :32 .<>oz<. 8::..:> :: m22:52 .: :33 45 Quantification involved the use of a xerox machine and a leaf area meter. In the field, leaves of corn plants were cut at their bases and immediately placed into Solo plastic cups filled with water. The plastic cups were labeled by tillage/cover-crop treatment, repetition and leaf number. Only the bottom four leaves were used (not including the cotyledon). Then the leaves were taken to the laboratory, and scotch-taped to a sheet of paper labeled with the treatment, repetition and leaf number. Next, the corn leaves were xeroxed. The leaves reproduced well; images of slug damage were easily differentiated from images of other types of invertebrate damage (Figure 8). The xerox leaf images were cut out with scissors and an estimate of the "total leaf surface area" (TLSA) (cm2) was determined using a leaf area meter. The TLSA was somewhat underestimated due to folding of the leaf during xeroxing. Next the slug damage images on each leaf xerox were excised with an x-acto knife and the area of the xeroxed leaves, with the ‘slug damage' images excised, was determined using the leaf area meter. This second estimate was an estimate of "undamaged leaf surface area" (ULSA). The "percent of the total leaf surface area damaged by slugs" (PTLSADS) was determined using the following equations. The ”leaf surface area damaged by slugs” (LSADS) was calculated (Equation A). From this the ”percent of the total leaf surface area with slug damage” (PTLSADS) was cal- culated (Equation 8). Equation A: LSADS = TLSA - ULSA Equation 8: PTLSADS = [(LSADS/TLSA) x 100] 46 300003 Leaf #3) . :1»...qu . Slug Foliar Damage .. .. . .. . . . $2.3.) ah$rWlwnmcfllyf . .. q .3632.“- . mu - cult. . . k. . v& 2... llll- ..l£.:12.4‘...o- . .. . L. u. 2.3., mm”. ... - u”. x. . Figure 8. Xerox of Slug Foliar Damage. 47 The number of slugs per plant during the early whorl stages of the Corn/Corn/Corn (C/C/C) rotation for comparison of the tillage/cover-crop treatments. Sampling was performed at night when slugs are most active (Byers 1983, Richardson and Whittaker 1982). The number of slugs per square meter on the ground were recorded after the harvest of 1983 in the Corn/Corn/Corn (CIC/C) rotation for comparison of the tillage/cover-crop treatments. Two square meter areas per plot were examined for the presence of slugs on the ground and in crop residues at the soil surface. Measurement of Percent Ground Cover Crop and Soil Science researchers determined the percent of ground covered by crop residues using the Mannering method. A wood frame of known area was placed on the soil. Slide photographs were taken of the area enclosed by the wood frame. After the slides were developed, a grid was imposed upon the slide. The percent area covered by plant residues was estimated within each section of the grid. These estimates were combined to obtain the final estimate of the percent of soil surface covered by plant residues. European corn borer methods and results are presented in Appendix 8. Corn rootworm methods and results are presented in Appendix C. Other invertebrate methods and results are presented in Appendix D. RESULTS Slug Damage Description A single species of slug, Agriolimax Mflller, was observed to damage corn plants. Slug damage was observed on the adaxial (upper) surface of the leaves. The slug damage could be easily distinguished from other types of pest damage using several visual characteristics (Figure 8). First, the orientation of slug damage on corn leaves was longitudinal. Second, the damage had ragged, irregular edges. Third, the abaxial leaf tissue (lower- most layer) was not consumed, but remained for several days to a week before it dessicated and ripped apart. The leaf edges were left intact, except those with high slug damage intensity. It was also possible to observe where slugs had traveled on the plant because of the shiny "slime trails" they left on the corn leaves. The 1982 surveys began during the mid-whorl stages and slug damage occurred throughout the whorl and reproductive stages of corn plant growth (Figure 9). In 1983 surveys began during the seedling stage. Slug damage in 1983 began during the early whorl stages. In contrast to 1982, slug damage in 1983 ended midway through the season by the late-whorl stages (Figure 7). During the late reproductive stages in 1983 trace slug damage was observed in a single plot. 1982 Damage Intensity The Alfalfa/Corn rotation had significantly less slug damage than the Corn/Corn (CIC) rotation (Chi-square P > .0001). 1982 Alfalfa/Corn (A/C) slug 48 .mme ucm ~32 .8 8332.35 .2323 Eou 22“. :_ wmmEmo m3.m .m 239”. 33033233. _ 32 2E 2.3 49 . I I I . “cwmnm I «:32... .mmmEmo .23”. .323 02:53 _ 2.2 28 2.3 0335 32.-u l.............:nw>0>53mwoc...... NQGP mwmw J 50 intensity, and the Corn/Corn (C/C) rotation slug intensity is shown in Figure 7 (Appendix A, Table 23). The difference between rotations was especially apparent during the mid-late whorl stages of corn growth. We did not detect significant differences in slug damage intensity in irrigation, manure or tillage/cover-crop comparisons (Appendix A, Table 24). Although significant differences were not detected, isolated plots of no- tillage with rye cover-crop (NR) in manured (M1) blocks of the Corn/Corn/Corn (c/c/c) rotation suffered up to 50% reduction in yield that directly resulted from stand-loss due to slugs (EIFS Rept. #38). 1983 Damage Intensity Slug damage intensity was highly correlated with slug damage incidence (Correlation Coefficient = .9487; P>F> = .0001; Figure 11) and the results of the analysis of variance and treatment comparisons were the same. To avoid redendancy, only the slug damage incidence will be presented here; Slug damage intensity statistics are given in Appendix 1, Table 25. 1983 Damage Incidence During the early whorl stages of corn, slug damage incidence from the three rotations covered a broad range of values (0-100%). The Alfalfa/Corn (A/C) rotation had lower slug damage incidence than either the Corn/Corn (CIC) and the Corn/Corn/Corn (CIC/C) rotations (Table 11). During the mid-late whorl stages, as slug damage declined, differences among the rotations were smaller than in the early whorl stages, however the Alfalfa/Corn (A/C) rotation still had the least plants with slug damage (Table 12). By the early reproductive and late reproductive corn plant growth stages, slug damage 51 T n .5th 63228 9.3 *o :0332235 3:333 33 .3 239... 33m 9.833232. 32.22 wmmwm 9.63.232. 2.5m mono-m :23 32-22 22.3 «~92 :33. 2323 mm=< 2.2.3 3...... 3.2.2 22.2 353.223 m. _. 3-8 3:322 33:35 ommwfio 3 m2 3.. N Cozbubm c..OU\m+_m:< cos-Sou EoHEou I. m.~ 52 3:22.33. ODDV EoEEoHEou 35 CD. 52253 ES.— 35205 3253 33m 222, 3.33:. mmmEmo 32m 2o 5322.3 mam. .3 239“. 3-8 952. 33:32 32:30 33 3 m2m m.m m~.m m mud m.~ m~.~ ~ mm; m2 m~2 2 mm. m. mm. o _ _ . _ _ . . _ a 3 q 3 3 . . 2 o 333. u N. .- 9 o I I :1 ON 1 cm . $0253 0 o o I. 0.? One-whet; 3:23? 2.. . 3:039:— . cm «3228 o o o o mud—m . . .. 8 .- on . . I 8 4 cm I cop S3 $3.9 o mm 86 med $8.87o 9 -.mm 5.9 . ODE EoHEoHEou $8.86 8 mod 2: $8.82. we 3.8 8.3 GOV 532.3 $8.? o 8 86 3.9 $8.8- o 8 3m mm.m Q3 583:8? ~82. z .m.m :85. 8:3. 2 .w.m :35. 8:33. $83 :23 33.22 893m .352, 3.3 .383 .355 33.2.2 0:: .355 2:3 8::: 33:38.5 8:33. 33:33:: «92:3 9.3 .3 «Em» 54 incidence was too low to detect differences among the rotations, or among othertreatments. Irrigation did not affect slug damage during any stage of crop growth (Appendix A, Table 26). During the early whorl stages, manure did not affect slug damage incidence (Table 13; Appendix A, Table 26). However, during the mid-late whorl stages, manure had a significant effect on slug damage. The significant manure x tillage/cover-crop interaction in the Corn/Corn (CIC) rotation (P>F = .028) shown in Table 14 resulted because slug damage in manure blocks (M1) was higher in some tillage/cover-crop treatments. During the early whorl stages in the Alfalfa/Corn (A/C) rotation, slug damage incidence was not affected by tillage/cover-crop treatments (Table 15; Appendix A, Table 26). However, tillage/cover-crop treatments did significantly affect slug damage in the Corn/Corn rotation (CIC P>F = .0016, Table 15) and also in the Corn/Corn/Corn rotation (CIC/C P>F = .0207, Table 15). Multiple comparisons of slug damage incidence among tillage/cover- crop treatments in the Corn/Corn (C/C) rotation indicate that the moldboard plow (PL) and no-till rye (NR) treatments respectively with the lowest and the highest slug damage incidences, were significantly different (Table 15). The no—till clover (NC), chisel plow (CP), regular no-till (NT) and no-till alfalfa (NA) treatments had intermediate damage and were not significantly different in the Corn/Corn (CIC) rotation. Multiple comparisons of tillage/cover-crop treatments in the Corn/Corn/Corn (CIC/C) rotation also indicated significant differences between moldboard plow (PL) and no-till rye (NR) (Table 15). Forty-six percent of the variation in slug damage incidence during the early whorl stages in non-manured (M0) blocks of Corn/Corn (C/C) and Corn/Corn/Corn (CIC/C) rotations could be explained by the percent of the 55 : Na 3 439 mNNNNm m . «338 cm . 2.8» 8 3V 55 moo Nm. Edam N £6 R: 8.33 m mNd N3 3.»? m «8:523:22 NE. «.3 3.83 N .380 N; 3,22 m we... Nod ENN. m 8392.: 3.32 N 2.88 m 3.8N m E 35 N2. 2.: 8.9.: F 3d $5 MNEE F N... 8N mmmmp . 2:555. 23 N3 :3me F Rd 8.0 News N 8... mm: No.8 m v.35 “XE H. mm 5 “.AE u. 3. 3 :AE H. mm ”a . 330m QUE 5823258 02 58:58 03 583.32 .383 torts 2:3 2: @550 32:33. COD. :3 \EouEBu :8 .UD. EouEEu .0): 538:3? 05 *o 333 3:235 *o m_m>_m:< 23:35:: o 2:8 5:3 .9 ~32. 56 Table 14. Slug Dama e (Incidence): Analysis of Variance Table of the Corn/Corn( C) Rotation during the Mid-Late Whorl Stages. Source DF SS MS F PR >FF Blocks 3 0.05 0.02 1.25 0.289 Irrigation (A) 1 0.00 0.00 0.10 0.750 Error (3) 3 0.16 0.05 Manure (B) 1 0.18 0.18 7.05 0.010" Man. x Irr. 1 0.02 0.02 0.02 0.339 Error.(b) 3 0.21 0.07 Tillage (8) 5 0.48 0.10 3.74 0.005‘“ Till. x In. S 0.06 0.01 0.43 0.824 Till. x Man. 5 0.35 0.07 2.73 0.028" Till. x Irr. x Man. 5 0.05 0.01 0.37 0.860 Error (b) 57 _ 1.45 0.03 TOTAL 89 57 .CVn V3 mo. u a «a 203.383 >33 9:... meo n a 3.: $2 a. u m g 8.8 22:262-? pm 5 m a: .3... .96: .362 - oz pm 2... 2 Rd 8.9.. £32,. .562 - <2 gm no 3.3 8.3 gm 3.. m one 8.3 .5342 a... . a. w E. : 8.3 so... .85 - no a a Ba 8...; m m w a} on... 262. 283202-: 2...“... .2... ........_.m. .2... z ODE 5825258 09 582:8 .mwmmum 29:5 2.3 2.: 9:53 532.3 2.: 5 3:25am; 33-86232: *0 «29.25 22:23. ODD. 582.3258 .25 D. anu 23:22 33526:: 3223 2m .3 £an 58 ground covered by plant residues (adj. quuare = .4657, Figure 12). The no- till rye (NR) treatment had greater than 90% average ground cover and had 80% average incidence of slug damage. The no-till alfalfa (NA) treatment, also had greater than 90% ground cover, but in contrast, only had 35% incidence of slug damage. During the mid-late whorl stages, even though slug damage was low, tillage/cover-crop treatments still affected slug damage incidence, but only in the Corn/Corn (CIC) rotation where manure and tillage interacted in their affect upon slug damage (Table 14). Only the no-till treatments (NT, NC and NR) had any slug damage. In manured (M1) blocks, no-till treatments with cover-crops other than alfalfa (NC and NR) had significantly higher slug damage than no-till (NT) (P = .05; Table 16). In the non-manured (M0) blocks, the no-till (NT) treatment alone had slug damage. This different ordering of slug damage incidence among tillage/cover-crop treatments between the manured (M1) and non-manured (M0) blocks produced the significant 'manure and tillage' interaction during the mid-late whorl stages. At this time slug damage was not detected in the moldboard plow (PL), chisel plow (CP) and no-till alfalfa (NA) treatments. During the early and late reproductive stages, slug damage incidence was negligible and we could not test for differences among tillage/cover—crop treatments. Percent of Leaf Surface Area Damaged by Slugs The Corn/Corn/Corn (CIC/C) rotation was sampled for percent of leaf surface area damaged by slugs. During the early whorl stages, tillage/cover- crop treatments significantly affected the percentage of leaf surface area damaged by slugs (P>F = .005; Table 17). In treatment comparisons, 59 .2352. 009 5858.58 .25 CD. 58.58 :33 9:65 235.. 55> 3520:. 32:8 2...». *6 223.293. mam. .NP 9.29“. A3223. «SE 5.2, 2:960 335“ :9 *o a}. hw>ou 959.0 «:33.— oop cm ow on om om ow om cm 0.. o hmmv. u ~m .637 .3 39:29 0 I om .ctgmwcma *0 $3 3520:. 1 oo 38:3 93 . .. E T H twbwm o 1.. cm 32....-o2 u 22 a>O_U:_w.02 u U2 1 cm 5.3.5562 u <2 .562 u #2 3223.6 u a... i 2: ".5... 58%65. u E 60 .OVn V3 mo. u a «m 331383 >mxa© u m 8.2 8.2 m w 88 88 9: .562 - 22 u m 8.8 88 m m 88 88 .263 .562 - uz m a 8.8 88 m w 88 8.8 3.33 .362 - <2 2 m 88 of a m 8.0 8. P .562 - E a w 8... 8... m w 8.0 8.8 26: .35 - “U a m 8.0 88 m m 88 8.0 26.2 2886.2 - 8 1:05 . . anew . . @233 z w m 28.2 @233 z m m 28.2 35:33; 323 E); .8582 85; 2582.52 . .393 to 3 83.2.2 «5 92:6 20:23. GOV EouEBu of E 236235 gums—3 x 9.3.2:: *o «camtmaEOU a. £22 #35292: mmmEmo 02m .3 ~32. 61 the no-till rye (NR) treatment had a significantly greater percentage of its leaf surface damaged than did the other tillage/cover-crop treatments (NT, CP and PL) (P: .05; Table 18). The significant differences obtained from these comparisons correspond to results of treatment comparisons of slug damage incidence (Table 14 and Table 15). Slug Numbers During the peak occurrence of damage in the early whorl stages, slugs were occasionally observed on corn plants in the early morning. From the mid-late whorl stages to thelate reproductive stages no slugs were observed. Then, during the late reproductive stages (on September 5, 1983), two slugs were found in a no-till (NT) tillage/cover-crop treatment in a non-irrigated (I0), non-manured (M0) plot of the Corn/Corn/Corn (C/C/C) rotation. After harvest, slugs were found on the soil surface and in the above-ground plant residues. The Corn/Corn/Corn (CIC/C) rotation was sampled for numbers of slugs. During the early whorl stages, tillage/cover-crop treatment significantly affected the number of slugs per plant (P>F = .0453; Table 19). In multiple comparisons, the no-till rye (NR) treatment had significantly more slugs per plant than other tillage/cover-crop treatments (NT, CP and PL) (P = .05; Table 20). After harvest, tillage/cover-crop treatment significantly affected the numbers of slugs per m2 (P>F = .0195; Table 21). In multiple comparisons, no-till treatments (NT and NR) had more slugs per m.2 than moldboard plow (PL) and chisel plow (CP) treatments (P = .05; Table 22). 62 Table 17. Percent of Total Leaf Surface Area Damaged by Slugs: Analysis of Variance Table of Tillage/Cover-crop Treatments in the Corn/Corn/Corn (CIC/C) Rotation During the Early Whorl Stages. Source DF SS MS F PR >F Blocks 3.48 1.16 2.18 0.607 Tillage (A) 11.21 3.74 6.99 0.018" Error (a) 12 6.42 0.53 TOTAL 15 Table 18. Percent of Total Leaf Surface Area Damaged by Slugs: Multiple Comparisons of Tillage/Cover-crop Treatment in the Corn/Corn/Corn (CIC/C) Rotation During the Early Whorl Stages. . Tukey@ Tillage Mean SE N group PL - Moldboard plow 0.46 0.08 4 a CP - Chisel plow 0.95 0.17 4 a NT - No-till 1.60 0.49 4 a NR - No-till rye 3.11 0.70 4 b @Tukey comparisons at P = .05 (aF Blocks 3 55.75 18.58 1.48 0.258 Tillage (A) 3 120.75 40.25 4.03 0.045“ Error (a) 12 119.85 9.99 TOTAL 15 Table20. Number of Slugs per Plant: Multiple Comparisons of Tillage/Cover-crop Treatment in the Corn/Corn/Corn (C/C/C) Rotation during the Early Whorl Stages. . ‘ Tukey@ Tillage Mean 5.5 N group PL - Moldboard plow 0.00 0.00 4 a CP - Chisel plow 0.33 0.33 3 a , NT - No-till 0.50 0.29 4 a NR - No-till rye 9.00 4.04 4 b @Tukey comparisons at P 2 .05 (aF Blocks 35.21 11.74 1.27 0.355 Tillage (A) 180.05 60.02 6.52 0.019" Error (a) 12 110.52 9.21 TOTAL 15 Table 22. Number of Slugs per Square Meter: Tillage/Cover-crop Treatment in the Corn/Corn/Corn (C/C/C) Rotation after Harvest. Multiple Comparisons of - Duncan@ Tukey Tillage Mean 5.15 N group group PL - Moldboard plow 1.00 0.65 4 a a CP - Chisel plow 1.37 0.42 4 a a NT - No-till 5.12 1.23 4 b a NR - No-till rye 5.00 2.02 4 b a @Duncan and Tukey comparisons at P = .05 (aF> .0001). In treatment comparisons, no-tillage alfalfa had significantly lower damage than all other tillage treatments (Chi-square P>F>.OOO1). Tables 29 and 30 lists the 1982 statistics for irrigation, manure and tillage/cover-crop treatments for the Alfalfa/Corn (A/C) and Corn/Corn (CIC) rotations. In 1983, the Alfalfa/Corn (A/C) and Corn/Corn (CIC) rotations had higher ECB foliar damage incidence during the mid-late whorl stages (first generation damage) than did the Corn/Corn/Corn (CIC/C) rotation (Table 31). ECB foliar damage incidence was significantly affected by manure, irrigation and tillage/cover-crop treatment in the Alfalfa/Corn (Table 32), Corn/Corn (Table 33) and Corn/CornlCorn (Table 34) rotations. Irrigation statistics are shown in Table 35. Manure statistics are shown in Table 36. In tillage/cover- crop treatment comparisons (Table 37), moldboard plow (PL) and chisel plow (CP) treatments consistently had the highest ECB foliar damage incidence. In contrast, the no-tillage cover—crop treatments of alfalfa (NA) and clover (NC) consistently had the lowest ECB foliar damage incidence. 79 ECB foliar damage incidence was significantly correlated with plant height and plant stage in the Alfalfa/Corn, Corn/Corn and Corn/Corn/Corn rotations (Table 38). In 1983, ECB stalk damage to corn plants (first and second generation damage) was significantly higher in manured (M1) blocks than in non- manured blocks in both the Alfalfa/Corn (P>F=.0001) and Corn/Corn (P>F: .0034) rotations. ECB stalk damage to corn plants (first and second generation damage) was not affected by irrigation or tillage/cover-crop treatment in any rotation. ECB corn stalk breakage was not significantly affected by manure, irrigation or tillage/cover-crop treatment during the Reproductive stages of corn plant growth. 80 .3333. .o 3333‘». 2053.235 .2333. 53:3:— ommEmo 5:0". 228 Eou :3 23 ~32 .m_. Saar. 38 2323 m3 «NE him otw m8 NNK ONR m FR 9R 3-8 3.23:. 3250 5:0“. Sum: .28 Eou cowaocam 5023.33 EoHEou I m 81 Table 28. 1982 European Corn Borer Foliar Damage Intensity Seasonal Distribution Statistics for Rotations. Survey Alfalfa/Corn Rotation Corn/Corn Rotation Date Mean Std. err. N Mean Std. err. N 7/10 0.37 0.06 80 0.62 0.07 80 7/13 1.41 0.13 80 1.95 0.21 80 7/20 1.30 0.10 80 1.73 0.11 80 7/27 2.43 0.22 80 1.58 0.17 80 8/3 1.85 0.17 80 1.33 0.15 80 8/10 1.58 0.18 80 0.85 0.10 80 8/17 1.26 0.14 80 0.80 0.09 80 8/24 0.97 0.11 80 0.58 0.06 80 9/3 0.40. 0.09 80 . 0.44 0.05 80 82 Table 29. 1982 European Corn Borer Foliar Damage Intensity Statistics -- Alfalfa/Corn Rotation. Treat- Mean Std. Mean Std. Mean Std. ment err. err. Bl'l'. 7/10 7/13 7/20 10 0.24 0.09 40 1.42 0.20 40 1.40 0.15 40 11 0.50 0.04 40 1.40 0.17 40 1.21 0.12 40 M0 0.22 0.07 40 1.47 0.20 40 1.32 0.14 40 M1. 0.53 0.05 40 1.35 0.17 40 1.29 0.14 40 PL 0.44 0.14 16 1.63 0.15 16 1.50 0.18 16 CP 0.44 0.14 16 1.83 0.34 16 1.50 0.15 16 NT 0.33 0.10 16 0.94 0.09 16 1.40 0.15 16 NA 0.28 0.11 16 0.79 0.10 16 0.79 0.09 16 NC* 0.37 0.11 16 1.85 0.15 16 1.33 0.25 16 7/27 8/3 8/10 I0 2.57 0.27 40 1.81 0.24 40 1.73 0.28 40 I1 2.29 0.33 40 1.89 0.24 40 1.53 0.23 40 M0 2.26 0.27 40 1.74 0.23 40 ' 1.72 0.27 40 M1 2.60 0.33 40 1.96 0.25 40 1.38 0.20 40 PL 2.73 0.18 16 2.25 0.35 16 2.04 0.10 16 CP 2.67 0.37 16 1.96 0.16 16 1.94 0.31 16 NT 2.77 0.24 16 1.73 0.26 16 1.35 0.18 16 NA 0.94 0.39 16 0.83 0.22 16 2.79 0.08 16 NC* 3.04’ 0.26 16 2.48 0.22 16 1.23 0.52 16 8/17 8/24 9/3 I0 1.35 0.19 40 1.07 0.16 40 0.25 0.07 40 11 1.18 0.21 40 0.87 0.15 40 0.54 0.16 40 M0 1.01 0.15 40 0.99 0.15 40 0.41 0.10 40 M1 1.52 0.22 40 0.94 0.16 40 0.38 0.16 40 PL 1.81 0.26 16 1.40 0.05 16 0.83 0.32 16 CP 1.50 0.26 16 1.17 0.07 16 0.25 0.09 16 NT 1.27 0.14 16 0.81 0.11 16 0.50 0.12 16 NA 0.31 0.07 16 0.17 0.06 16 0.27 0.09 16 NC* 1.42 0.21 16 1.29 0.18 16 0.13 0.04 16 IO = non-irrigated . PL 2 moldboard plow I1 = irrigate CP = chisel plow NT 2 no-tillage M0 = non-manured NC = no-tillage clover cover-crop M1 = manured NA = no—tillage alfalfa cover-crop ‘no-tillage clover was tilled identically to moldboard plow in alfalfa/corn rotation (see Table 7, Materials and Methods). 83 Table 30. 1982 European Corn Borer Foliar Damage Intensity Statistics -- Corn/Corn Rotation. Treat' Mean Std. Mean Std. Mean Std. ment err. err. err. 7/10 . 7/13 7/20 10 0.57 0.08 40 1.80 0.30 40 1.64 0.13 40 I1 0.67 0.11 40 2.11 0.29 40 1.83 0.17 40 M0 0.64 0.08 40 1.72 0.25 40 1.78 0.12 40 M1 0.59 0.11 40 2.19 0.33 40 1.68 0.18 40 PL 0.67 0.08 16 2.98 0.28 16 1.94 0.14 16 CP 0.87 0.20 16 2.13 0.48 16 2.04 0.31 16 NT 0.50 0.10 16 2.06 0.19 16 1.92 0.15 16 NA 0.33 0.08 16 0.79 0.31 16 1.08 0.10 16 NC 0.71 0.08 16 1.81 0.28 16 1.69 0.09 16 7/27 8/3 8/10 l0 1.58 0.24 40 1.29 0.23 40 0.66 0.11 40 I1 1.59 0.23. 40 1.37 0.18 40 1.03 0.13 40 M0 1.56 0.23 40 1.42 0.18 40 0.95 0.14 40 M1 1.61 0.24 40 1.24 0.22 40 0.74 0.12 40 PL 2.10 0.58 16 2.10 0.30 16 1.00 0.17 16 CP 1.69 0.42 16 1.52 0.05 16 0.90 0.22 16 NT 2.04 0.50 16 1.19 0.24 16 1.04 0.1 S 16 NA 0.79 0.23 16 0.52 0.14 16 0.31 0.07 16 NC 1.29 0.38 16 1.31 0.18 16 0.98 0.16 16 8/17 8/24 9/3 l0 0.77 0.14 40 0.54 0.07 40 0.41 0.08 40 I1 0.82 0.09 40 0.62 0.08 40 0.47 0.07 40 M0 0.87 0.12 40 0.62 0.06 40 0.51 0.08 40 M1’ 0.72 0.11 40 0.54 0.09 40 0.37 0.07 40 PL 1.00 0.09 16 0.69 0.02 16 0.67 0.12 16 CP 1.17 0.11 16 0.75 0.11 16 0.35 0.09 16 NT 0.85 0.15 16 0.44 0.10 16 0.50 0.15 16 NA 0.44 0.21 16 0.48 0.16 16 0.33 0.06 16 NC 0.54 0.04 16 0.54 0.11 16 0.33 0.06 16 IO = non-irrigated PL = moldboard plow II = irrigated CP = chisel plow NT 2 no-tillage M0 = non-manured NC = no-tillage clover cover-crop M1 = manured NA = no-t1llage alfalfa cover-crop *no-tillage clover was tilled identically to moldboard plow in alfalfa/corn rotation (see Table 7, Materials and Methods). 84 Table 31. 1983 European Corn Borer Foliar Damage Incidence -- Mid-late Whorl States Rotation. Rotation Standard Mean error N Alfalfa/Corn (NO 41.00 2.59 96 Corn/Corn (C/C) 37.30 2.85 96 Corn/Corn/Corn (C/C/C) 12.80 2.06 80 85 Table 32. 1983 European Corn Borer Foliar Damage Incidence in Mid-Late Whorl Stages (ANOVA -- Alfalfa/Corn Rotation). SOURCE DF 55 F PR>F SIG Rep 3 0.13 2.09 .1123 NS In 1 0.16 7.30 .0091 ** Rep x Irr 3 0.15 2.39 .0781 NS Man 1 0.22 10.37 .0021 ** Rep x Man 3 0.03 0.45 .7164 NS In x Man 1 0.02 0.75 .391 NS Rep x Irr x Man 3 0.06 0.98 .408 NS Till 5 3.40 31.99 .0001 *** lrr xTill 5 0.12 1.11 .3635 NS Man x Till 5 0.21 1.98 .0957 NS lrr x Man x Till 5 0.05 0.48 .7923 NS Residual 56 1.19 Total 91 5.74 Rep 2 Repetition lrr = Irrigation Man 2 Manure Till = Tillage Table 33. 1983European Corn Borer Foliar Damage Incidence in Mid-Late 86 Whorl Stages (ANOVA -- Corn/Corn Rotation). SOURCE DF SS F PR>F SIG Rep 3 0.07 .67 .0005 *** Irr 1 0.03 0.95 .344 NS Rep x In 3 0.13 1.19 .3228 N5 Man 1 0.16 4.06 .0355 * Rep x Man 3 0.04 0.35 .7875 NS lrr x Man 1 0.10 2.54 .0927 NS Rep x Irr x Man 3 0.15 1.38 .2573 NS Till _ 5 3.96 20.07 .0001 *** In x Till 5 0.30 1.71 .1466 NS Man x Till 5 0.27 1.55 .1886 NS m x Man x Till 5 0.11 ' 0.61 .6904 NS Residual 56 2.02 Total 92 7.34 Rep = Repetition lrr = Irrigation Man 2 Manure Till = Tillage 87 Table 34. 1983 European Corn Borer Foliar Damage Incidence in Mid-Late Whorl Stages (ANOVA -- Corn/Corn/Corn Rotation). SOURCE DF 55 F PR>F SIG Rep 3 0.21 2.51 .0705 NS Irr 1 0.26 9.58 .0033 ** Rep x Irr 3 0.05 0.60 .6179 N5 Man 1 0.00 0.09 .7649 NS Rep x Man 3 0.09 1.04 .384 NS Irr x Man 1 0.00 0.00 .9635 NS Rep x lrr x Man 3 0.03 0.33 .8051 NS Till 5 0.39 3.55 .0131 ** In x Till .5 0.21 1.88 .1292 NS Man x Till 5 0.09 0.83 .5147 NS lrr x Man x Till 5 0.01 0.18 .8328 NS Residual 46 1.26 Total 75 2.59 Rep = Repetition lrr = Irrigation Man = Manure Till = Tillage 88 85:62 u :2 35:92:02 n 92 9‘ end 093 we 91V omev Q.» 3.: ommv :2 ov om.m «v.3 wv mvm om.~m mv wmmm wmmm 02 z .tm .63 :32 z .tw .3m :82 z :3 .3m :82 1 6.065 m2 mvwm. n u. A mm :0339... EoEEoEEou 2mmmo. n n. A an :22me EouESu t. :8. n a A E 8:23. 585.23 65:22 :_ momma .355 33.22 .- 3:022. 39:3 :28 Eou 52.9.3. 32. .mm 032. 369:. u : .85 _:_-:oz u o. 8 2.2 32 we Rm 3% 3 ohm $2M : 8 $6 3.2 we 23 comm 9W1! Rm 9.? 9. z .2363 :82 z .twfifi :82 z .twfiwm :82 I Vno; f. mmoo. n u. A mm 6330: Eou\Eou\Eou mz 03m. n m A E :osflom Eou\::ou .1 Eco. u u. A an. 8222: £85.22 £259... :_ 393m .555 33.22 .. 8520:. 0383 Show Eou :moaosm mag .mm 03m... 89 no.0-c0>ou 03. 09.362 u 22 aob-0>ov .060 000.562 u u2 0020-:0>ou 0:32 0mm..z-oz u <2 08.5-62 .1. 22 26.2.8.5 u RU 2>0... 0.003.032 u .E 0 m. afim 3.0 n 3 «Wm 3.3 0 5 RM mmdv «2 0 3 3d New n 9 SM 3.3 uz 6. 2.: Rd omd n. 3 mmé 3.3 0 o. cod cod <2 0 3 ~56 wmép n 9.. £6 mwdm no 3 0...? mmdv .2 m m: em... 32: m 8 21.. ~22... 6 8 m: 3.3 6 m 3 and 3.8 0 3 -.m 3.3 0 3 ~06 :dm .5 0:90 .220 0305 :0 0:96 50 28.3 z .62". 28.2 28.3 z .63 £22 28.3 z .63 :85. 690-660 2096:: 5.233. 53.50858 6:33. 53.53 8233. 533:2? 20.500... 0mm...» .0 0.035 .22.; 0.3.2.2 -. 00:00.05 03.23 20:00. 20.3 Sou :00023 33 Km 030» 90 Table 38. Correlations of European Corn Borer Foliar Damage Incidence with Corn Plant Height and Corn Plant Stage. Plant height r2 P4>F NC .9749 >.0001 C/C .5866 >.0001 CIC/C .7479 >.0001 Plant stage r2 Pr>F NC .9839 >.0001 C/C .5204 >.0247 CIC/C .0417 >.0071 NC = Alfalfa/Corn Rotation CIC = Corn/Corn Rotation CIC/C = Corn/Corn/Corn Rotation Appendix C. Corn Rootworm Methods Corn rootworm adult numbers were recorded (as described in the general methods section) in 1982 on a weekly basisfrom the Mid-Whorl through Late-Reproductive stages of corn plant growth. In 1983 the number of corn rootworm adults per plant was not used as a measure because using this measure we did not detect trends or significant differences due to tillage/cover-crop treatment in 1982. Results The Alfalfa/Corn (A/C) rotation had the fewest corn rootworm adults per plant in 1982 (Chi-square P>F>.0001, Figure 14, Table 39). Adult rootworms appeared earlier in the season in the Corn/Corn (C/C) rotation than in the Alfalfa/Corn rotation. Statistics for irrigation, manure and tillage treatments for 1982 are given in Table 40 (Alfalfa/Corn Rotation) and Table 41 (Corn/Corn rotation) 91 92 5:23.... 3:23 2.2.3 E8333. Eou 2o 5.23.5.0 3530.6. 32. .2. 05m...— m0wmp mEEmE m3 «NB 5 Cm o Cw m3 N~R GNP m E o In .1 2:03 .0: 203632 2% 5023.024 :._ou\Eou I, m 93 Table 39. 1982 Seasonal Distribution Statistics for Corn Rootworm Adult Numbers per Plant. Survey Alfalfa/Corn Rotation Corn/Corn Rotation Data Mean Std. err. N Mean Std. err. N 7/10 0.00 0.00 80 0.00 0.00 80 7/13 0.00 0.00 80 0.08 0.03 80 7/20 0.00 0.00 80 0.25 0.04 80 7/27 0.07 0.01 80 0.39 0.06 80 8/3 0.50 0.03 80 1.27 0.09 80 8/10 0.46 0.04 80 0.94 0.04 80 8/17 0.56 0.05 80 1.00 0.09 80 8/24 0.51 0.05 80 0.75 0.06 80 9/3 0.16 0.03 80 0.24 0.02 80 94 Table 40. 1982 Corn Rootworm Adult Counts (#lplant) Statistics -- Alfalfa/Corn Rotation. Treat- Std. Std. Std. ment Mean err. N Mean err. Mean err. N 7/10 7/13 7/20 l0 0.00 0.00 40 0.00 0.00 40 0.00 0.00 40 I1 0.00 0.00 40 0.00 0.00 40 0.00 0.00 40 M0 0.00 0.00 40 0.00 0.00 40 0.00 0.00 40 M1 0.00 0.00 40 0.00 0.00 40 0.00 0.00 40 PL 0.00 0.00 16 0.00 0.00 16 0.00 0.00 16 CP 0.00 0.00 16 0.00 0.00 16 0.00 0.00 16 NT 0.00 0.00 16 0.00 0.00 16 0.00 0.00 16 NA 0.00 0.00 16 0.00 0.00 16 0.00 0.00 16 NC* 0.00 0.00 16 0.00 0.00 16 0.00 0.00 16 7/27 8/3 8/1 0 10 0.05 0.01 40 0.51 0.05 40 0.40 0.03 40 I1 0.09 0.02 40 0.49 0.04 40 0.50 0.08 40 M0 0.09 0.02 40 0.45 0.05 40 0.44 0.07 40 M1 0.05 0.00 40 0.55 0.04 40 0.48 0.05 40 PL 0.07 0.01 16 0.50 0.06 16 0.55 0.14 16 CP 0.10 0.05 16 0.53 0.06 16 0.42 0.04 16 NT 0.04 0.01 16 0.47 0.03 16 0.56 0.12 16 NA 0.03 0.00 16 0.41 0.08 16 2.82 0.07 16 NC* 0.09 0.02 16 0.60 0.09 16 0.43 0.04 16 8/17 8/24 9/3 I0 0.61 0.09 40 0.55 0.08 40 0.15 0.04 40 I1 0.52 0.03 40 0.47 0.06 40 0.17 0.04 40 M0 0.67 0.08 40 0.55 0.08 40 0.16 0.03 40 M1 0.46 0.03 40 0.47 0.06 40 0.16 0.04 40 PL 0.49 0.04 16 0.64 0.14 16 0.18 0.03 16 CP 0.44 0.06 16 0.43 0.04 16 0.24 0.06 16 NT 0.48 0.03 16 0.31 0.02 16 0.22 0.07 16 NA 0.71 0.15 16 0.55 0.13 16 0.09 0.02 16 NC* 0.69 0.14 16 0.62 0.09 16 0.09 0.03 16 I0 = non-irrigated PL = moldboard plow I1 = irrigated CP 2 chisel plow , NT 2 no-tillage M0 = non-manured NC = no-tillage clover cover-crop M1 = manured NA = no-tillage alfalfa cover-crop *no—tillage clover was tilled identically to moldboard plow in alfalfa/corn rotation (see Table 7, Materials and Methods). 95 Table 41. 1982 Corn Rootworm Adult Counts (#lplant) Statistics -- Corn/Corn Rotation. Treat- Std. Std. Std. ment Mean err. Mean err. N Mean err. N 7/10 7/13 7/20 l0 0.00 0.00 40 0.10 0.04 40 0.19 0.03 40 I1 ' 0.00 0.00 40 0.06 0.04 40 0.31 0.07 40 M0 0.00 0.00 40 0.08 0.04 40 0.24 0.06 40 M1 0.00 0.00 40 0.08 0.04 40 0.26 0.05 40 PL 0.00 0.00 16 0.25 0.09 16 0.44 0.11 16 CP 0.00 0.00 16 0.10 0.03 16 0.40 0.07 16 NT 0.00 0.00 16 0.00 0.00 16 0.12 0.00 16 NA 0.00 0.00 16 0.02 0.01 16 0.20 0.04 16 NR 0.00 0.00 16 0.01 0.01 16 0.10 0.01 16 7/27 8/3 8/10 l0 0.28 0.04 40 1.12 0.12 40 0.89 0.08 40 11 0.50 0.10 40 1.43 , 0.09 40 0.98 0.04 40 M0 0.33 0.04 40 1.24 0.10 40 0.82 0.06 40 M1 0.45 0.10 40 1.31 0.14 40 1.05 0.04 40 PL 0.64 0.11 16 1.10 0.06 16 0.88 0.11 16 CP 0.52 0.09 16 1.58 0.15 16 1.08 0.06 16 NT 0.33 0.07 16 1.03 0.24 16 0.91 0.07 16 NA 0.17 0.04 16 1.40 0.10 16 0.78 0.07 16 NR 0.31 0.08 16 1.25 0.19 16 1.03 0.10 16 8/17 8/24 9/3 I0 0.96 0.13 40 0.75 0.10 40 0.25 0.04 40 I1 1.04 0.1 1 40 0.76 0.06 40 0.24 0.02 40 M0 0.76 0.09 40 0.70 0.06 40 0.19 0.02 40 M1 1.24 0.10 40 0.80 0.10 40 0.30 0.04 40 PL 0.81 0.14 16 0.44 0.02 16 0.16 0.02 16 CP 0.86 0.07 16 0.78 0.09 16 0.20 0.02 16 NT 1.10 0.21 16 0.92 0.09 16 0.29 0.07 16 NA 1.24 0.26 16 0.93 0.15 16 0.25 0.04 16 NR 0.99 0.16 16 i 0.69 0.09 16 0.31 0.06 16 IO = non-irrigated PL = moldboard plow I1 = irrigate CP = chisel plow NT 2 no-tillage M0 = non-manured NC = no-tilIage clover cover-crop M1 = manured NA = no-tillage alfalfa cover-crop Appendix D. Other Invertebrate Methods Damage that could not be attributed to any particular organism, but which. we determined was incurred by an invertebrate (e.g. grasshoppers or caterpillars, sawfly) was put into the general category of "other invertebrates". Also included into this category were invertebrate pests causing identifiable but insignificant amounts of damage (e.g. flea beetle, cereal leaf beetle, thrips). In 1983, we began sampling corn plants for pests and damage during the Seedling stages of corn plant growth in the Corn/Corn/Corn (C/C/C) rotation. We were not ableidentify the particular pests causing damage at this time, therefor it fell under the category of "other invertebrate” damage. ”Other invertebrate" damage intensity and incidence (as described in the general methodology) were recorded. During the Mid-late Whorl Stages of corn plant growth, flea beetle damage incidence (as described in the general methodology) was recorded in the Alfalfa/Corn (A/C), Corn/Corn (C/C) and Corn/Corn/Corn (CIC/C) rotations. Results The first damage observed in Seedling stage corn was a shothole-type of foliar damage. The damage appeared to be randomly distributed on the leaves. We did not observe the invertebrates causing this damage, but when we set up pitfall traps, sawfly larvae were captured in these traps in the same plots where we observed the damage. 96 97 "Unidentified invertebrate" damage intensity and incidence of in the Corn/Corn/Corn (CIC/C) rotation during the Seedling stage was not Significantly affected by manure applications. "Unidentified invertebrate" damage was significantly affected by tillage (P > F = .0001). In treatment comparisons, the no-tillage (NT) and no-tillage rye (NR) treatments had the highest intensity (Table 42) and incidence of damage (Table 43). Flea beetle damage incidence was Significantly higher in irrigated blocks of the Alfalfa/Corn (P>F 2.0001), and Corn/Corn/Corn (P>F: .0001) rotations during the Mid-late Whorl stages of corn plant growth (Figure 15). In the Corn/Corn rotation flea beetle damage incidence was also higher in irrigated blocks (Table 16), although the difference was not Significant. 98 Table 42. 1983 Unidentified Invertebrate Foliar Damage Incidence for Tillage/Cover Crop Treatment Comparisons. Experiment Treatment Mean SE. 3-year PL a .1035 .1344 3-year CP ab .1996 .1771 3-year NT c .4238 .2562 3-year NR bc .3899 .2056 *Treatments with the same letter are not Significantly different at the .95 level of confidence by Tukey's multiple comparison; ANOVA given in Table 2.a.4. . Table 43. 1983 Unidentified Invertebrate Foliar Damage Intensity for Tillage/Cover-Crop Treatment Comparisons. Experiment Treatment Mean SE. 3-year PL a 43.31 .2485 3+year CP ab 56.86 .2484 3-year NT ab 67.68 .2562 3-year NR bc 73.94 .2056 *Treatments with the same letter are not significantly different at the .95 level of confidence by Tukey's multiple comparison; ANOVA given in Table 2.a.4. 99 £03.33. 58.8.3.2. :. 30.....manu 2.0.500... 00.u..0>0u\0mm...h .0. «093m .355 0.3.0.2 05 05.00 02.0.0.0... 092:3 5:0“. 0.200m m0... .2 222: 100 .mcom..manu 0.00 m 8.. 0309......02 0:0 2.: 1023.... .3 “093m .355 0.3.2.2 05 92.0.0 00:00.0... 0 088 5:0". 0.200» 00... .3 0.00... :.ou\:.0u\:.0u :.ou\:.ou 58.2.8.4 0002.00 5.3 3cm... .x. REFERENCES Aldrich, S.R., W.O. Scott and ER. Leng. 1975. Modern Corn Production. A&L Publications, Champaign, IL. 308 p. All, J.N. and RN. Gallaher. 1976. Detrimental impact of no-tillage corn croppin systems involving insecticides, hybrids, and irrigation on lesser cornstal borerinfestations. J. Econ. Ent. 70:361-365. Alessi, J. and J.F. Power. 1971. 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