Sustainable Agriculture Research and Education in the Field A Proceedings (1991) / Chapter Skim
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PART THREE: RESEARCH AND EDUCATION IN THE SOUTHERN REGION
PART THREE: RESEARCH AND EDUCATION IN THE SOUTHERN REGION
Pages 163-228
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From page 163... ...
PART THREE Research and Education in the Southern Region
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Pest management programs in both Virginia and Georgia have sought to provide good regionally adapted control (Taylor and Dobson, 19743. The authors of this chapter have tried to provide growers with dependable, low-risk, preventative spray guidelines and to emphasize regional pest biology and selective, well-timed pesticide use.
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From page 166... ...
impractical for Georgia and Virginia growers since leafminer sprays provide plant bug control. Green fruitworms also are controlled at the pink and petal fall stages with sprays made for other pests.
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, is fostered by making every effort to avoid unnecessary pesticide use. Careful pest management minimizes all unwarranted pesticide use (Croft and Brown, 1975~.
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Conidia of B obtusa are produced on dead wood in the trees and on the orchard floor throughout the year (Beisel et al., 1984~.
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PATHOLOGY RESEARCH University of Georgia LISA fruit research centered on the development of IPM-compatible controls for sooty blotch and fly speck. The heavy preventative spraying required to control these diseases was not conducive to further pest management implementation.
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Values with the same symbol are not significantly different. Postharvest Removal of Sooty Blotch and Flyspeck Initial testing of postharvest chlorine dips in 1988 showed that these treatments removed sooty blotch and reduced flyspeck.
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Pesticide residues were reduced by the postharvest chlorine treatment (Table 10-3~. Captan resi TABLE 10-3 Effects of a 5-Minute Dip of 500 ppm of Chlorine Followed by Brushing and Rinsing with Nonchlorinated Water on Residues of Captan, Phosmet, and Maneb on Harvested Apples Residues (ppm)
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From page 172... ...
Fruit finish was not affected at 4,100 ppm of chlorine, with or without buffer, even when fruit was stored for 30 days in plastic bags in the presence of chlorine solution. Conclusions of Fruit IPM Research Postharvest chlorine dips have been found to be an effective technique for the removal of sooty blotch and the reduction of flyspeck.
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From page 173... ...
Postharvest chlorine treatment has allowed Georgia growers to eliminate up to eight sprays that, in preventative programs, are dedicated, at least in part, to the control of sooty blotch and flyspeck. No chlorine treatment-induced phytotoxicity was observed, even when eight times the necessary concentrations or two times the necessary exposure durations were used.
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From page 174... ...
Because these leafrollers are not direct fruit feeders, control of fruit damage may be attained without complete mating disruption. Variegated leafroller capture has been suppressed to a greater degree than has tufted apple budmoth capture.
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Ground Cover Management Inventory A survey of the ground cover management practices of Virginia growers was expanded to all pesticides and plant growth regulators that are applied to fresh-market apple orchards. About 45 conventional growers responded.
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This probably accounts for the low densities of this predator that have been observed. Assessment of Grower Expertise for IPM Evaluations have revealed that most growers in Virginia are lacking in critical pest management skills.
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From page 177... ...
Sprayings that were solely for insect control were made to alternate row middles to hold down costs and conserve predators. Prepink and pink sprays were applied to the alternate row middles for spotted tentiform leafminer, tarnished plant bug, and green fruitworms in a scheduled preventative fashion.
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From page 178... ...
Fungicides are applied on a prescription basis. Sanitation is practiced by pruning out and removing as much dead wood from the trees as possible and by either removing dead wood from the orchard and destroying it or mowing the wood on the orchard floor with a
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From page 179... ...
If scab, rust, and Brooks spot have not been a problem in the orchard in the past, it is not necessary to apply sprays for these diseases. If they have been a problem, the sprays suggested in the Georgia apple spray guide should be applied.
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The percentage of apples that could be packed, after chlorine treatment for sooty blotch and flyspeck was equivalent to that in the Georgia spray guide blocks. TABLE 10-7 Insect Injury to Harvested Apples in 1989 Grower Trials in Georgia Loss (%)
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1989. Economic threshold for tarnished plant bug (Hemiptera: Miridae)
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University Park, Pa.: Cooperative Extension Service, The Pennsylvania State University.
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The concept of low-input sustainable agriculture (LISA) has emerged that addresses multiple objectives: increasing agricultural profitability, conserving energy and natural resources, and reducing soil erosion and loss of plant nutrients (Harwood, 1990; Schaller, 19893.
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From page 184... ...
Recent research has demonstrated that stocker cattle grazed on tall fescue-alfalfa (Festuca arrundinacea-Medicago sativa) during fall and winter made higher daily gains both during the growing phase and again 1 year later when these cattle were finished on corn silage (Allen et al., 1989b)
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From page 185... ...
Legume cover crops can contribute more than 80 lbs of N per acre to the succeeding crop (Corak et al., 1987; Ebelhar et al., 1984; Hargrove, 1986; Mitchell and Teel, 1977; Neely et al., 1987~. Extensive work on the use of legumes in conservation tillage systems has been summarized by Power (19874.
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In the low-input corn research project reported here, the central focus is the integration of winter-annual cover crops into ridge-till systems for corn production. Particular emphasis is placed on weed management, evaluation of mechanical cultivation, the role of the cover crop mulch in weed suppression, and banded herbicide applications.
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. Insect pest management practices in the low-input system rely on rotational effects, and insecticides are applied based on pest population sampling and economic thresholds.
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Establishing the Crop Rotation Sequence LISA System In order to initiate the crop rotation sequence required in this experiment, Cimmaron alfalfa was seeded into three blocks and corn was seeded into the fourth block in the spring of 1989. Pioneer 3192 corn was no-till drilled into herbicide-killed sod in 1.5-acre blocks with four replications.
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From page 189... ...
evaluation of the contribution of various winter-annual legume and small grain combinations to silage corn production, (2) evaluation of alternative cover crop management practices for winter-annual cover crops in no-till corn (comparing the effects of rotary mowing with those of conventional herbicide desiccation)
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ratios were determined prior to disk incorporation or desiccation. The effects of cover crops and tillage practices on weed densities, water infiltration rates and soil moisture, seasonal N uptake, and corn silage yields were determined.
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Averaged across both years and cover crops, the no-till system produced a $44 greater net return per acre than that of the disk tillage system. Within the no-till system, the hairy vetch cover crop produced net returns of about $22/acre greater than that of the rye cover crop with 125 lbs of N per acre.
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From page 193... ...
Additional long-term research is needed to incorporate these variables into economic analyses of cover crops. Evaluation of Alternative Cover Crop Management Practices for Winter-Annual Cover Crops in No-Till Corn The second subproject for developing a low-input corn system involved the evaluation of alternative cover crop management practices for rye cover crops in no-till corn, comparing the effects of mowing with those of conventional herbicide desiccation.
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TABLE 11-3 Estimated Net Return to Management from Corn Silage Following Two Cover Crop Treatments and Two Tillage Methods Estimated Net Return ($/acre)
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per acre, which cost $40.35/gallon in 1990. The recommended application rate for paraquat for contact killing of rye cover crops is 1.5 to 2.5 pints/acre (Webb et al., 1988~.
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~ 0.2 0.6 O UJ UJ ~3 C, En lo G LL LL At: > at; 4 _ 2 _ 1 _ O . 96 SUSTAINABLE AGRICULTURE FIELD RESEARCH AND EDUCATION Allison, 1989 | ~8 6 6 _ ,~' "my ° 4t /i~ I -- a- sprayed 1 6 t Cover crop kill treatments 0 mowed Bishop, 1988 be, \ '` \ ()
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197 ~ a' ~ o ~ : ~0 ~ 1 1 1 1 1 1 1 1 1 1 ~ 1 i 1 ~ 1- 1 1 1 1 0 oo ~cad 0 ao CM ~ ~ (duo) coda 30~11S NUOO ~CM o o cn ._ -Cal CO _ En U
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From page 198... ...
Evaluation of Ridge-Till Corn Production Systems Using Winter-Annual Cover Crops Weed management practices were evaluated in a ridge-till corn production system using winter-annual cover crops. The experiment was conducted at the VPI&SU Whitethorne Research Farm, near Blacksburg, Virginia.
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From page 199... ...
Cultivation apparently stimulated germination of smartweed, with significantly more smartweed biomass than when no weed control treatment was used. Weed biomass in the furrows, where there was a thick mulch of cover crop residue, was considerably less than that on the ridges, where the soil was disturbed and no mulch existed.
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Although these first-year results are preliminary, they indicate that the ridge-till system, in which a mowed cover crop was used for mulch and a very shallow skimming of the ridge was used during planting, may provide significant levels of weed control, reducing the need for both mechanical and chemical weed controls. A second-year replication of this experiment is in progress, with rye-hairy vetch cover crops established in the fall of 1989.
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It answers a fundamental need in the pursuit of a sustainable agriculture because it is impossible to implement low-input sustainable practices without addressing the whole-farm planning problem. Planning crop rotations involves or influences (1)
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3. A multicounty farmer educational meeting on sustainable agriculture in Amelia County was cosponsored by the Virginia Cooperative Extension Service and the Virginia Farm Bureau Federation.
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Research on the integration of cover crops into low-input ridge-tillage systems will also continue. Development of the computeraided crop rotation farm planning system will be continued, with on-farm testing of the system anticipated in 1991.
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1987. The need for legume cover crops in conservation tillage production.
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1989. Profits and risks of using crimson clover and hairy vetch cover crops in no-till corn production.
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Through proper selection of living mulch cover crops, weed competition may be eliminated because of allelopathic or smothering effects from the mulch barrier (Putnam, 1988) , and nutrient inputs could be supplied by the decomposing mulch (Wagger, 1989~.
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. · to investigate the feasibility of eliminating fertilizer and herbicide inputs on blueberries grown in the South by using legumes and annual forage rotations for living mulches, and · to evaluate solarization and cover crops or manures as replacements for fumigation and fertilizers in annual strawberry production in the South.
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A somewhat different experimental protocol was followed in Texas. During the winter and summer, cover crops were planted at five grower locations and at the Overton experiment station farm.
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Barker subterranean clover Common hairy vetch Summer 1989 Tifleaf pearl millet Headless wonder sorghum Green graze sorghum Sudan Iron and clay cowpeas Sun hemp crotalaria Everglades 41 Kenaf Sericae lespedeza Winter 1989-1990 Gulf ryegrass Elbon rye Dixie crimson clover Common hairy vetch Yucchi arrowleaf clover D-3 rose clover HO HO? FR, CH HO, FR, CH, OV HO HO OV,NC, HV, RU, TY HO HO, OV, NC,NC HO OV HO OV,NC OV,NC CH, FR, OV, NC, HV, RU, TY OV,NC OV OV,NC, HV, TY, WB OV,NC,TY, WB OV,NC, HV, WB OV,NC, HU, TY, WB OV,NC, HV, TY, WB OV OV HO, OV, NC, HV, TY, WB OV,NC, HV, TY, WB HO, OV, NC, HV, TY, WB OV, WB OV, WB, TY OV Very p`~(>r tr' fair'f Very poor to good'f Very poor to ~oodt' Poor to fair1' Very poor to good ~ Poor to very goodl- i: Very poor''' ~ r .I.
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Weed suppression with cover crops was assessed by measuring weed densities in the field and allelopathic responses in the laboratory. Several crops were assessed for their allelopathic suppression of weed seed germination.
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Overton Winter 1988-1989 Elbon rye2,948a t0 2,103a ~5,642a Triticale - 3,799b Marshall ryegrass 1,963c Wheat 2,005a 3,038bc Crimson clover951b0 2,394a 2,537bc Subterranean clover587b0 Ob 1,991c Hairy vetch 4,224b Summer 1989 Pearl millet17,460a11,563a 4,898a 26,550a 8,202b Sorghum Sudan16,942a1,410c 4,269a 21,895b 7,715b Sorghum20,803a 21,044b 7,056b Cowpeas~0 b5,009b 6,151 a 12,901 c 7,558b Crotalaria~0 b0 d 1,251 b 14,463c 17,91 Oa * Overhead irrigation was used at this location.
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For example, when summer nonlegume cover crops were grown on a minimum N fertilizer program (50 lbs of N/acre) , they exhibited severe N stress symptoms, and all had leaf N levels of less than 0.6 percent (data not
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The poor crop stands of crimson clover in 1990 TABLE 12-4 Weed Control Between Blueberry Rows as Affected by Living Mulch Cover Crops Percentage of Ground Covered by Weeds* Nacogdoches Nacogdoches Crop Plot 1 Plot 2 Winnsboro Overton Pearl millet l5b't 20c la 3a Sorghum Sudan 52b 31bc Stab 26b Sorghum 39b 36c 9ab 22ab Cowpeas 1 00c 50b 45bc Crotalaria 99c -Jr 66c Control 1 00c 94a *
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. A single application of manure per year, however, may not provide sufficient N to grow both a winter and summer living mulch The high levels of manure required to supply the nutrient inputs for the cover crops may have an adverse effect on seed germination or, over the long term, may increase soil pH or P levels above the range desired for blueberry plants.
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The estimated cost of growing and using cover crops for living mulch twice a year was $300/acre of blueberries. These costs represent approximately $80 more than those associated with fertilizers and herbicides in conventional blueberry production programs.
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agriculture system, however, is unlikely to be cost-effective during the transition time between systems. During this period, weed control and nutrient input from living mulches may not be completely satisfactory.
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Experimental Protocols In the Overton experimental plots, the following experimental protocol was used. In 1987-1988, the soil treatments were 6 weeks of solarization, fumigation with 400 lbs of 98 percent methyl bromide and 2 percent chloropicrin per acre, or a control.
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Soil temperatures were monitored by placing thermocouples at soil depths of 4 and 8 inches. For the 1989-1990 season, whole-plot soil treatments were expanded to include legume cover crops or manure combinations.
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The yield was higher with fumigated soil than with solarized soil in 1988, but there was no difference between fumigated and solarized plots in 1989. Plants grown on 13-inch beds tended to have a greater total yield than did those grown on 8-inch TABLE 12-7 Effect of Soil Treatment on Strawberry Yield and Weed Control Surface Area Covered by Weeds (%)
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Weed Control Weed control in response to soil treatments varied by species. There was no difference in the number of annual dicots per plot between fumigation and solarization plots in 1988, and both treatments had fewer annual weeds than the control plots did (Tables 12-7 and 12-8~.
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levels were reduced on solarized soil compared with those in untreated soil (Table 12-10~. Manure applied before solarization markedly increased soil pH, electrical conductivity, potassium, calcium, magnesium, phosphorus, ammonium, zinc, manganese, and copper.
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The reduction in annual weeds with solarization may explain some, but not all, of the increase in yield over that in untreated soil. In several other studies on solarization, increased plant growth response has also been reported in the absence of major soilborne pests (Katan, 1981; Stapleton and Devay, 1986~.
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From page 223... ...
The goal has been to attempt to build a supply of slowly released N and other nutrients in the soil, under the plastic, that could supply several sequential crops with adequate fertilization. Direct manure applications have resulted in the most vigorous plants at the lowest cost in comparison with a combination of winter and summer legume cover crops and manuring followed by a nonlegume cover crop (data not shown'.
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Option 1: Chicken manure delivered and spread at 15 tons/acre t Option 2: 600 pounds of 13-13-13 NPK fertilizer/year + 10 supplemental N applications at 20 lbs/acre through a drip line Soilborne pest controller Option 1: Black plastic + hand weeding Option 2: Solarization (cost of plastic laying,, pigmenting, occasional hand weeding) Option 3: Fumigation (custom application)
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From page 225... ...
1989. Time of desiccation effects on plant composition and subsequent nitrogen release from several winter annual cover crops.
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Frisbze This reaction is to three sustainable agriculture projects in the southern region described in the following chapters: "Southeastern Apple Integrated Pest Management" by Dan L Horton and colleagues, "Low-Input Crop and Livestock Systems in the Southeastern United States" by John M
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From page 227... ...
The project at Texas A&M University described by Kim Patten and colleagues that deals with strawberries and blueberries in eastern Texas is a good example of how to design a sustainable agriculture system in soils with extremely low levels of organic matter and that receive low levels of rainfall in summer. Although this research program has been under way for only a short time, it has shown that ground cover and other management strategies that may work in some areas of the country are not suitable everywhere.
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