Performing Department
(N/A)
Non Technical Summary
Barley yellow dwarf virus is transmitted by several species of cereal aphids and has been a threat to winter wheat in the southeastern USA in recent years. Integrated pest management (IPM) is the most effective approach to managing BYDV and aphids. However, the recommended strategies in the southeastern USA (i.e., planting date, seed treatment, and/or timing of foliar insecticide application) are based on information generated more than two decades ago, which no longer fit to our current climate patterns or best management practices. This proposal aims to provide research-based support for the effective management of BYDV and cereal aphids in winter wheat in the southeastern United States and develop much-needed, up-to-date educational material to prevent the unnecessary application of insecticides and promote the implementation of IPM. We will also provide estimates of expected revenue associated with implementing each practice and develop a calculator and educational material to assist producers with the decision-making process.
Animal Health Component
0%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Goals / Objectives
The overarching goal of this project is to provide research-based support for the effective management of cereal aphids and BYDV in winter wheat (and other small grains) in the southeastern United States and to develop much-needed up-to-date educational material and workshops to prevent unnecessary application of insecticides and promote the implementation of IPM. There are four specific project objectives that are interconnected:i. Test the natural vegetation in and around fields to identify regional reservoirs of BYDV and aphid vectors in Virginia,ii. Establish field plots to determine and demonstrate appropriate practices to minimize BYDV;ii.1. Demonstrate the effectiveness of planting time in evading BYDV infection.ii.2. Compare the efficacy of neonicotinoid seed treatment and foliar pyrethroid applications in managing cereal aphids and BYDV.iii. Determine yield loss due to BYDV and estimate farm profitability implications of BYDV damage and adoption of the control practices evaluated through Obj. ii. iv. Develop educational material and conduct workshops to increase grower awareness of recommended management practices for controlling BYDV.
Project Methods
Objective 1: Identifying regional reservoirs of BYDV and aphid vectors. We will sample foliar tissue from grasses in grazing land and the adjacent winter wheat (or other cultivated small grains) to identify potential virus reservoirs. Sampling will cover areas known for frequent BYDV outbreaks as well as areas where BYDV occurrence was not reported in 2021 and 2022 (as control fields)..Sampling will be conducted twice in each year of the project, once in September and once in March. Each year, at least 40 winter wheat fields across Virginia, either adjacent to forage grasses or to other non-grass crops (primarily soybean and tobacco) at the time of planting, will be considered for this objective. Sampling consists of inspecting plants and counting cereal aphids and removing plants from a one square foot area every 50 feet, for a maximum of 200 ft of the wheat fields and the neighboring grazing land on two rows that are 100 ft apart (a total of 20, 1-ft samplings from the wheat field and its neighboring grazing land). The first row will be at least 10-ft away from the edge of the field (or grazing land). The collected plants will all be transported or shipped overnight to the Southern Piedmont Entomology Laboratory in Blackstone, VA, and evaluated for BYDV presence using the quantitative reverse transcription polymerase chain reaction (RT-qPCR) test. To detect and quantify BYDV, 100 mg of leaf tissue will be removed from two fully expanded young leaves. RNA extractions will be performed using a Qiagen RNeasy plant mini kit. cDNA synthesis and BYDV titer quantification will be carried out by a Luna® Universal One-Step RT-qPCR Kit (New England Biolabs) with forward and reverse primers according to Balaji et al. (2003). The percentage of plants found positive for the BYDV will be estimated for each of the collected plant species. A generalized linear mixed model with a nonlinear distribution (TBD based on data) will be used to predict whether BYDV incidence in a wheat field is influenced by its proximity to grazing land. Spearman rank correlation can be used to examine the relationship between disease incidence and aphid pressure. In addition, plant species that may serve as BYDV reservoirs (and alternative cereal aphid hosts) will be identified. Species identification will be sent to Virginia Tech Weed Identification Laboratory for confirmation.Objective 2: Establish field plots to determine and demonstrate appropriate practices to minimize BYDV.Two-year field experiments will be conducted on the research farm of Virginia Tech's Southern Piedmont Agricultural Research and Extension Center in Blackstone, VA, as well as on Leslie Farms located in Amelia, VA (see letter of collaboration and support). In each location, there will be three experimental fields, 200 feet apart, planted mid-September ('early planting'), mid- to late-October (commonly practiced; hereafter, 'optimal planting'), or late-November ('late planting'). Plots planted early, optimally, and late are separated to reduce the risk of aphid movement from early-planted plots to plots planted later into the fall. The commonly used winter wheat variety in the southeast region, Shirley, will be used in both locations. For each location, there will be six treatments (including the control) per planting time: 1) untreated control, 2) neonicotinoid seed treatment, 3) fall broad-spectrum foliar insecticide application (upon aphid detection), 4) spring broad-spectrum foliar insecticide application (upon aphid detection), 5) neonicotinoid seed treatment + fall foliar insecticide application, 6) neonicotinoid seed treatment + spring foliar insecticide application. Treatments will be replicated 4 times within each planting time arranged in a randomized complete block design (24 plots per planting time/location; 144 plots, total). In both locations, plots will be 5 × 30 ft, planted with a 5-ft Zurn D82 planter. Replications will be planted 10 feet apart to maximize exposure to incoming aphids from reservoirs (as opposed to between plot movements early in the season). The spaces between experimental fields and plots will remain fallow. A Zurn 150 combine will be used to harvest all plots and record yield.Each plot will be monitored and sampled every ten days starting day five post-germination (80% emergence) in the fall and ending in early April. Monitoring includes counting the number of aphids per 5 randomly selected plants perpendicularly across each plot and removing the aboveground tissues for BYDV testing. RNA will be extracted, and the number of BYDV copy numbers (titer) will be quantified using RT-qPCR. A generalized linear mixed model (repeated measure) will be used to compare BYDV incidence (percent positive) and aphid numbers among treatments within each planting date and across planting dates over time. A generalized linear mixed model assuming a normal distribution and an identity link function will be used to analyze yield data among treatments.Objective 3: Determine yield loss due to BYDV and estimate farm profitability implications of BYDV damage and adoption of the control practices evaluated in objective ii. We will estimate the profitability implications associated with each IPM strategy evaluated in objective 2. To estimate revenue losses to BYDV, we will use yield and pesticide usage data collected from the implementation of the plot trials described under objective 2 in both years of the study. Specifically, to obtain estimates of expected revenue, the yield data from the trials implemented under objective 2 will be combined with wheat market prices to estimate revenues associated with each treatment. For production costs, existing enterprise budgets for wheat production in the eastern and southeastern US will be used as a baseline regarding fertilizer, pesticides, labor, and equipment-related usage in winter wheat production. These enterprise budgets will then be adjusted to reflect changes in the usage of any production-related inputs associated with the investigated IPM strategies. Costs associated with inputs needed for the implementation of the IPM strategies and that were not encompassed into the production-related assumptions for the baseline enterprise budgets will be obtained from project collaborators who buy materials for implementing the field trials. Since the field trials will be implemented over the course of 3 years, the profitability estimates for the first year will be updated in years 2 and 3 to reflect updated yield-to-BYDV infestation relationship information and associated yield and price variability as observed in the field trial and price data. Based on the estimated variability of yields and prices, and hence, profitability, a "breakeven analysis" will be implemented in each year that field trials are implemented. Multiple years of data will provide more realistic ranges for yields and prices that can be expected under various production conditions and wheat market conditions.