Evaluations of economic benefits and long-term sustainability of neonicotinoid seed treatment use in the mid-Atlantic

View the project final report

• 2016 annual report

Commodities

• Agronomic: corn, soybeans, wheat

Practices

• Crop Production: crop rotation, double cropping
• Education and Training: extension
• Pest Management: chemical control
• Soil Management: organic matter, soil analysis, soil chemistry, soil microbiology, soil quality/health

Neonicotinoids, which are the most widely used class of insecticides in the world, are most commonly applied as seed treatments. When this application technique is used, only a small proportion of the active ingredient is taken up by the plant. The majority of the insecticide remains in the soil, where it may accumulate with repeated use. There are many concerns regarding potential non-target effects of neonicotinoids, including their adverse effects on soil health as a result of their accumulation in the soil. This study examines the impacts of neonicotinoid seed treatments (NSTs) in a three-year field crop rotation (soybean, wheat, double cropped soybean and corn) at two sites in Maryland. Specifically, we are studying the effects of NSTs on pest suppression and yield, as well as non-target effects on arthropods and soil microbial communities. The prophylactic use of NSTs may not always be economically justifiable or in keeping with the principles of Integrated Pest Management (IPM); their impact on yield varies with pest pressure, and their persistence in the environment depends on factors such as physical soil properties. However, there is a lack of region and crop-specific guidelines for the use of NSTs, making it difficult to determine when their use is appropriate. This study will increase our understanding of the effects of NSTs in our region and will help growers make management decisions that will allow them to use NSTs in a profitable and sustainable way.

The primary objectives of this study are as follows:

Objective 1: We will examine the effects of NSTs on arthropod pest populations in order to determine whether their use results in significant suppression of economically important pests. We will also determine whether the use of NSTs results in a consistent increase in plant growth and yield.

Objective 2: We will evaluate whether NSTs cause non-target effects on the arthropod community, and whether those effects become more pronounced with repeated use.

Objective 3: We will examine the effects of using NSTs on soil health, and evaluate whether these effects increase with repeated applications. Specifically, we are investigating their effect on various physical characteristics of the soil, as well as the soil microbial community, with an emphasis on nitrifying bacteria. We will also evaluate the commercially available Solvita soil respiration test kits (Woods End Laboratories, Mt. Vernon, ME), available for use by farmers, for their accuracy as indicators of microbial abundance in comparison with molecular diagnostic tools, specifically quantitative PCR.