Evaluating Abiotic Factors Associated with Onion Maggot Control Failure in Northeastern Onion Production Systems

View the project final report

Commodities

• Vegetables: onions

Practices

• Pest Management: chemical control, integrated pest management

Onion maggot (Delia antiqua) is a significant pest of onion in the Northeast. In New York, where 90 percent of the Northeast’s onion production is concentrated, onion maggot can cause yield losses upwards of 50%, which threatens the viability of onion production in the region. Growers use cultural and chemical controls to manage this pest and predominantly rely on insecticide seed treatments. However, inconsistent performance of seed treatments has resulted in the increased use of chlorpyrifos, an environmentally harmful organophosphate insecticide, as an in-furrow drench applied at planting. To curb the excessive use of chlorpyrifos, the mechanisms behind increased onion maggot abundance and the failure of seed treatments alone to control this pest must be better understood. The purpose of this project is to investigate how local climate, soil temperature, and moisture impact onion maggot abundance regionally as well as within fields and to determine how soil moisture impacts seed treatment dissipation in this system. Information generated from this project will improve current onion maggot prediction models and enable growers to assess their risk for onion maggot based on moisture levels anticipated within their fields. This project will also contribute much needed information on the effects of seed treatment dissipation and its consequences for plant protection against herbivory. Altogether, this work will help to improve management of onion maggot and is one of the first steps in reducing reliance on chlorpyrifos and improving sustainability in Northeastern onion production.

The long-term goal of this project is to identify abiotic factors associated with increased onion maggot pressure and control failures and to evaluate how those factors impact control measures, specifically seed treatments. To achieve this goal, I propose the following objectives:

1) Evaluate associations between local climate and soil conditions (temperature and moisture) on the occurrence and relative pressure of onion maggot across onion producing regions of New York. We hypothesize that regions with greater seasonal precipitation, higher soil moisture, and lower temperature maxima will have a greater relative abundance of onion maggot compared with fields that have lower precipitation and soil moisture and higher temperature maxima in the spring.

2) Identify within-field conditions associated with onion maggot damage in fields where control failure occurs annually. We hypothesize that as soils within fields increase in soil moisture retention, exhibited by features such as low topography, organic matter content, and moisture holding capacity, we will see an increase in damage from onion maggot.

3) Assess uptake of novel, reduced-risk seed treatments under conditions of chronically high and low soil moisture in greenhouse studies to estimate insecticide dissipation and the potential for reduced control of seed treatments. We hypothesize that conditions of increased moisture will be associated with reductions in insecticide uptake by onion plants and increased damage by onion maggot.

4) Share research findings with Northeast onion growers