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2021 Row Crop Disease Update 21 July 20, 2021


Since sending out recommendations on disease management opportunities for peanut, I have been asked a couple of questions that I think will be of common interest to many, so I’ll try to answer them here.  It is important to remember that the recommendations were based upon two scenarios.

 Scenario 1:  It is now approximately 60 days after planting.  Grower was able to make a leaf spot application at approximately 30 days after planting but has not been able to get back in the field until now.  The grower missed a fungicide application at 45 days after planting and there is the real possibility that leaf spot diseases and white mold are now active in field.

Scenario 2:  It is now approximately 60 days after planting and NO fungicide application has been made in the field.  Grower should assume leaf spot and white mold are active in the field.

Subsequent questions:

  1. “Bob, you discouraged use of Miravis at 60 days after planting because you view this fungicide best used PRIOR to the development of leaf spot in a field. I was planning an Elatus+Miravis application at 60 days so now what?  ANSWER:  Good question.  Miravis is an excellent leaf spot material best applied before disease appears in the field.  Given early season delays in fungicide applications and the possibility for leaf spot to develop, even if undetected, I think it best not to use Miravis in the 60 day application.  Use an aggressive and curative leafspot spray at 60 days, and if good scouting shows the disease is in check, Syngenta Crop Protection recommends initiating an Elatus/Miravis program no more than 14 days later. If an aggressive program is used (as noted in earlier recommendations) and leaf spot diseases are effectively managed, then it is possible to use Miravis later in the season coupled with Elatus.  Bottom line:  Miravis + Elatus could be an outstanding application, IF leaf spot is “shut down” before that application.
  2. “Bob, you didn’t mention sulfur and I had planned to mix it with my Umbra.  What is your recommendation on that?”  ANSWER:  Specific formulations of sulfur at 5 lb/A have been very effective in improving leaf spot control when tank-mixed with products like Umbra, Excalia, Abound, and Headline.  Specific sulfur formulations offer the grower to better manage leaf spot diseases.  Given Scenarios 1 and 2, I am hesitant to use sulfur ALONE when mixed with Umbra (or other products) at 60 days after planting, as CURATIVE activity is essential and sulfur is not curative. However, including sulfur in a mix with curative fungicides at 60 days after planting would be ok.  Mixing sulfur with appropriate products at later dates would be appropriate, especially if leaf spot has been effectively managed bu earlier aggressive curative applications.
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