Performing Department
Plant & Soil Sciences
Non Technical Summary
The research outlined in this proposal would explore five general areas of concern pertaining to organic pest and disease management strategies for apple production: 1)the effects of organic disease management strategies on populations of disease-causing organisms, on disease incidence, severity and inoculum availability, and rate of disease increase in organic systems, 2)the effects of organic disease management strategies on populations of non-pathogenic phylloplane microbes, 3)the effects of organic insect management strategies on populations of insect pest and pest damage, 4)the relative performance of various apple cultivars in an organic system, and 5)the relative costs and benefits of organic disease management strategies to the apple industry, and some initial test marketing. The common focus, as well as goal, of these areas of research is a better understanding of organic pest and disease control practices in orchards and the prospects for using organic pest and disease management strategies in commercial orchards. Diseases of concern in West Virginia apple orchards are numerous and include apple scab, powdery mildew, cedar-apple rust, fire blight, Brooks spot, bitter rot, black rot, white rot, sooty blotch and flyspeck. The potential for implementation of organic strategies to manage apple diseases is enhanced, relative to fruit destined for the fresh market, by the fact that disease tolerance in processing apples is generally greater. Greater tolerances exist for powdery mildew, sooty blotch and flyspeck, whereas there is little tolerance for apple scab, cedar-apple rust, fire blight, and fruit rot diseases.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
Our objectives aim to compare yield, fruit quality, and multiple-year risks of organic apple disease and insect pest management in West Virginia via field and post-harvest experiments. Objective 1: determine the effects of organic disease management strategies on populations of disease-causing organisms, on disease incidence and severity, inoculum availability, and rate of disease increase in organic systems; Objective 1a: determine orchard floor ascospore density measurements and ascospore concentrations for apple scab; determine orchard floor and within-plant populations of rot organisms; study the potential for suppression of rot inoculum by mechanical substrate destruction and mechanical tillage; Objective 2: determine the effects of organic disease management strategies on populations of phylloplane microbes, and determine populations of yeasts, filamentous fungi, and epiphytic bacteria on leaf surfaces receiving organic management treatments; Objective 3: determine the effects of organic pest management strategies on populations of insect pests and on pest damage in organic systems; Objective 4: determine the relative performance of five apple cultivars in an organic system and identify their strengths and weaknesses for organic culture; Objective 5: determine the relative risks, costs and benefits of organic pest and disease management strategies to the apple industry; Objective 5a: collect economic cost and return data for the various organic practices; and, Objective 5b: test market organic fruit in West Virginia and Washington, D.C.
Project Methods
Organic cultural practices will include treatment of prunings with a flail mower to separate the bark from the xylem, thus rendering the prunings unsuitable for the reproduction of rot pathogens. In addition to inoculum reduction, summer rot diseases will be managed (as described above) by increasing host resistance via regular (every two weeks for a total of 65 kg/ha/yr) applications of calcium during the summer and preharvest period as a nutritional supplement to limit the occurrence of calcium-related disorders that may serve as infection courts for rot pathogens. Fruit on the orchard floor will be removed within one week to eliminate these as sources of inoculum for the current season. A postharvest application of compost tea or organic nitrogen source will be made to hasten leaf litter decomposition, thereby reducing apple scab inoculum for the following spring. Lepidopteran pests, including spotted tentiform leafminer, Oriental fruit moth, codling moth, and tufted apple bud moth will be monitored with Scenturion delta traps for each species installed in the center of the experimental plot. Apple maggot (AM) will be monitored with a single disposable plastic red sphere coated with tangletrap and baited with a vial of apple essence installed in the center of the plot. Traps will be checked and insects removed weekly, with Lepidopteran lures replaced every 6 weeks, and AM spheres and apple essence replaced every 3 weeks. Injury from fruit-feeding insects will be determined at harvest by evaluating 50 apples from each of 4 single-tree replications per cultivar in each section of the block that will be collected near optimum fruit maturity dates. Internal worms will be collected from harvested fruit and identified to species. Trap monitoring and fruit injury data will also be taken (4 single-tree replications/treatment) from conventionally managed and untreated trees in an adjacent block of Golden Delicious trees. Ten trees per subplot were selected randomly for routine monitoring of insect and mite populations, foliar disease incidence, weed populations, and tree growth. The same ten trees were used during the 3-year period. Tree growth was determined by measuring: 1) trunk cross-sectional area at 20 cm above soil level, 2) tree height, 3) tree width, and 4) number of lateral branches. We will partition risk assessments into multiple-year risks (main plots) and production-season risks (cultivar plots). Two main-plot treatments will each incorporate 3 production-season treatments arranged in a randomized complete block with 4 replications of 10 trees each. One main plot will use best management practices to prevent pest overwintering, including flail mowing or composted-manure fertilization in late fall to reduce scab pathogen survival in fallen leaves, chipping of pruned branches to reduce fruit rot pathogen survival, and removal of dropped apples to prevent codling moth survival. One other main plot will be a control (no treatments to reduce overwinter survival).