Evaluating the Impact of Insecticides on Arthropods in Cover Crop to Corn Transitions.

View the project final report

Commodities

• Agronomic: annual ryegrass, corn
• Animals: arthropods

Practices

• Crop Production: cover crops, cropping systems
• Education and Training: on-farm/ranch research
• Natural Resources/Environment: biodiversity
• Pest Management: chemical control, traps
• Sustainable Communities: sustainability measures

Cover crops have continued to increase in acreage across the US as a sustainable means of improving soil health, reducing soil runoff from fields, and as an alternative strategy to manage weeds. To maximize these benefits producers are encouraged to allow cover crops to grow as long as possible in the spring before planting a cash crop. Conversely, such practices can be counterproductive if a cover crop harbors arthropods that cause damage to the subsequent cash crop. In such cases, farmers may attempt to mitigate these threats by tank mixing an insecticide at the time of termination of the cover crop. Tank mixed insecticides are relatively cheap but are unlikely to control insects that secluded within the stems of the cover crop that emigrate to the cash crop several days after a herbicide application. In addition, the use of insecticides will likely kill beneficial insects in cover crop systems. In 2017, we reported a newly emerging pest, the wheat stem maggot (WSM) (Meromyza americana Fitch) in rye and wheat cover crop to corn systems. Yield losses from this pest have spurred an increase in insecticide use when terminating a cover crop. Farmers also face potential losses from other insects associated with cover crops such as black cutworm, true armyworm, common stalk borer and stink bugs. Insects such as common stalk borer and wheat stem maggot are only likely to be controlled when migrating between the cover crop and cash crop. Research is needed to address the best management practices for arthropod pests and beneficials in cover crop to corn transition systems. The proposed study will be conducted with two farmers to address efficacy of delayed insecticide applications relative to cover crop termination on insect pests and the impact of this practice on beneficial arthropods. Results from this study will enhance the education of farmers and consultants by providing them with the skills necessary to scout cover crops for pest and beneficial arthropods, protect the environment by reducing unnecessary insecticide applications, and increasing profitability of grower by providing them with information on when to apply. Findings will be disseminated through field days, conferences, CropWatch articles, as well as extension and research publications.

This study will increase our participant knowledge of arthropods and their pest or beneficial impact in cover crop to corn transition systems. Knowledge gains will occur through hands-on participation in data collection during field visits, demonstration plots at the Eastern Nebraska Research and Extension Center, extension publications, and presentations at fields days and conferences. These experiences will increase participant awareness on the activity and abundance of pest and beneficial arthropods when insecticides are used in cover crop systems. Participation in data collection, demonstration plots and information from presentations will provide participants, with the skills to properly scout for and group arthropods in these systems as beneficial or pest. Results from the study will also provide farmer with information on the efficacy of insecticides application timing to control key pests and skills to properly time applications.
Several action outcomes are anticipated from this project. We expect an increase in scouting efforts of cover crop fields prior to termination as a result of the training and hands-on experience as well as the ability to weigh the presence of beneficial insects in cover crop systems. Such skills should result in a reduction in tank-mixed insecticides at cover crop termination. When pest pressure is high we anticipate that producers will adjust timings of insecticides to achieve greater efficacy resulting in reduction in situations with significant economic losses and a greater return on investment.