Be Proactive Against Crop Disease

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Scouting corn field for weeds

Because disease development is highly influenced by weather and further progression in corn and soybeans can be rapid, it’s important for you to be proactive with disease management plans.

Jason Gibson, market development specialist, Corteva Agriscience, says white mold in soybeans and tar spot in corn are two diseases that should be on your radar this year. “Areas that were significantly impacted by white mold in 2021 will likely be planted to soybeans again this year, and corn acres affected by tar spot continue to grow each season,” he says.

Here are five ways you can stay ahead of crop disease this season:

  1. Prioritize scouting during key reproductive periods. Weekly scouting is ideal to check the presence and progression of disease in your fields. “If weekly scouting isn’t practical, prioritize getting in fields when the crop canopy begins to close and during key reproductive periods,” Gibson says.

    In corn, this means scouting during V10-V12 growth stages and around tasseling time. For soybeans, you’ll want to be in the field during R1-R3 and R4-R5 growth stages, especially if weather conditions favor disease development.
  2. Use free phone applications. University of Wisconsin-Madison has developed models to forecast disease risk. You can enter operation-specific information, and the application will help identify the best timing for disease treatment in your fields. Gibson recommends using Sporecaster for white mold and Tarspotter for tar spot.
  3. Time fungicide applications wisely. One of the most important factors when using fungicides for disease control is timing. Disease history, hybrid or variety tolerance ratings and weather conditions (both current and predicted) are all factors to consider. It’s also important to understand which diseases go from infection to sporulation quickly.

    “Diseases that progress rapidly, such as northern corn leaf blight and tar spot, present more risk waiting to see what happens versus taking immediate action,” Gibson says. “You won’t get back the leaf area lost to disease preceding an application, so it’s always better to apply too early rather than too late.”

    Most fungicides are very effective for a two- to three-week period. Timely applications can maximize the value of the application and reduce the need for return applications.
  4. Select the right fungicide. A fungicide labeled for white mold control may not offer the same level of control for tar spot. Work with your retailer to choose the right fungicide(s) to target the expected disease pressure on each field. Gibson also recommends a premix that includes both preventive and curative ingredients for the most effective control. And if you suspect any disease resistance, be sure to use fungicides with multiple effective modes of action against those specific disease challenges.
  5. Choose resistant hybrids. Consider hybrid or variety selection as a first step in disease prevention next season. “Don’t underestimate the value of knowing the hybrid or variety resistance score to diseases in question,” Gibson says.

Consult your local retailer or Corteva Agriscience representative and check out our Corn & Soybean Disease ID Guide for more detailed management recommendations for common Midwest crop diseases.