Current Situation:
Foliar applications of broad-spectrum, contact insecticides are often made to soybeans in Illinois to control a variety of insect pests. Often these applications are made at a specific growth stage, such as beginning pod formation (R3). However, damaging populations of insect pests may occur at different times throughout the soybean production season and target different growth stages. For example, stink bugs, which have grown in importance in Illinois in recent seasons, typically reach their highest population densities at the pod fill stages (R5-R6). Information on the effective window of control provided by an insecticide is usually not readily available to producers. This window can vary dramatically from product to product and depending upon weather conditions. Ready access to information on the effective window of activity provided by commonly used insecticides would allow producers and crop advisors to optimize the timing of these materials, thereby improving their return on investment.

Approach:
A series of small-plot insecticide efficacy trials will be conducted at various locations in Illinois. These trials will be located in soybean fields (at University of Illinois research farms and/or on commercial soybean fields) that are experiencing a damaging infestation of one or more insect pests. Once spray applications are made, insect population densities will be assessed in the field at three, seven, and ten days post-application, with additional intervals measured as necessary. In addition, soybean foliage (defoliating insects) or pods (stink bugs) will be collected, brought to the laboratory, and placed on benzamidazole-agar media (this prevents the plant tissues from wilting) in petri dishes. Pest insects (stink bugs, bean leaf beetles, Japanese beetles, and/or green cloverworm larvae) will be introduced to this insecticide-treated foliage, and mortality will be observed after 24 hours of exposure. These assays will be conducted until all insecticide-treated foliage no longer results in mortality of the insects. We will conduct four of these experiments during summer of 2020, with each one testing mortality of at least one of our target pests. If funded for 2020, we would seek continuing funding for 2021 and 2022 to repeat these studies across multiple growing seasons and environmental conditions. In addition to a scientific manuscript, the results of this project will be published in the University of Illinois Crop Sciences Applied Research Results on Field Crop Pest and Disease Control, a yearly summary of the results of applied research trials that have direct relevance to producers and crop advisors. In addition, a web-accessible database that includes the expected duration of control will be produced and made available to soybean producers, crop advisors, and other pest management clientele.

1. Determine the duration of control provided by commonly used foliar insecticides for major insect pests (stink bugs, bean leaf beetles, Japanese beetles, and green cloverworm) when exposed to field conditions.

2. Develop a web-based platform to make this information available to producers and crop advisors to help inform management decisions in Illinois soybean fields

The aim of the project is to conduct at least four field experiments during summer of 2020 which will evaluate insecticide materials against four target insects: stink bugs, bean leaf beetles, Japanese beetles, and green cloverworm. This should result in residual activity information for these four pests that can be published through a web-based application.

Outputs:

A web-based application made available to the public through the University of Illinois Cooperative Extension Service.

A scientific manuscript based on the results of these experiments.

Updated October 16, 2020:

View uploaded report

Constraint: Insecticides commonly used for broadcast applications in Illinois soybeans have periods of residual activity that vary depending on material used, insect species, and environmental conditions. However, this information is not readily available to farmers.

Opportunity: By evaluating the residual activity period of common insecticides and making this information available, we hope to empower growers to use these tools more effectively for insect control.

Farmers, crop consultants, Extension personnel, and scientists will have access to emipirical data on the residual control provided by common insecticides used in soybean. This information will be used to directly inform control decisions in the field and management recommendations provided by Extension, crop consultants, and others.