Calculate Your Soybean Disease Risk

New Take Action resource helps determine risk of soybean disease development

A new resource on the Take Action website can help farmers assess the risk of disease in their soybean fields.

The Know Your Disease Risk fact sheet contains an easy-to-fill-out chart in which farmers can score their fields based on common disease risk factors: crop rotation, tillage, variety disease-susceptibility, overhead irrigation, weather conditions before plant reproduction, and planting date.

Each of these factors, referred to as categories on the fact sheet, have a corresponding risk scale. After adding the total from each category, farmers have a better understanding of their disease risk for foliar diseases and white mold.

The ideal score is less than eight, where the risk for disease development is low. To obtain this score, farmers should consider incorporating six management best practices: rotating two or more crops, planting disease-resistant varieties, managing crop residue using tillage, managing irrigation use to reduce unnecessary periods of extended wetness, and planting at the optimal time. While farmers can control these factors, weather is beyond their control, but also incorporated into the formula. In years when dryer weather during the vegetative and early reproductive stages is predominant, risk for disease is further reduced.

Damon Smith, a plant pathologist at the University of Wisconsin-Madison who helped develop the fact sheet, says “Ideally we want farmers to achieve a score of less than 8. The tactics used to gain that score will maximize the efficacy of fungicides and slow fungicide-resistance development. It is a win-win. A score of 8 might be hard to achieve in some years, but getting as close as you can will help preserve certain active ingredients into the future”

A big concern in agriculture is fungicide resistance, so farmers should only apply fungicides when necessary. The Know Your Disease Risk fact sheet is a helpful tool for use in that decision-making process, assisting farmers in determining if fungicide application is warranted. Applying fungicides only when necessary can reduce the risk of fungicide resistance development, since disease-causing pathogens will be exposed to the fungicide less often, offering the pathogen less opportunity to overcome the active ingredients.

This resource shouldn’t be the only practice influencing farmers’ disease-management decisions. Smith recommends farmers scout ahead of critical times to spray for foliar diseases.

“This will help gauge disease levels and determine if the crop is at risk at the optimal time to spray,” says Smith. “If no disease is present and weather has been dry, a fungicide might not be needed. For a disease like white mold, paying attention to weather before and during soybean bloom helps make the decision to spray or not. If it has been cool and wet at this time, a spray might be necessary.”

Using this fact sheet in conjunction with other Take Action resources gives farmers a better understanding of how to remain profitable and sustainable. By applying fungicides only when necessary, farmers are saving money, time, and the risk of resistance for seasons to come. Take Action has many resources available for farmers to stay current on best management practices, which can all be found at www.IWillTakeAction.com.