Peanuts: Terminating Fungicide Sprays

We are starting to dig some peanuts this week in the county. Profiles are showing high percentage of mature, gradable peanuts. This week, it seems as profiles have slowed and not much change. One of the most difficult decisions is terminating our fungicide sprays. Some fields still show hits of white mold. Remember that if we get 60-70% control of soilborne disease, this is considered good – especially fields prone to WM.

peanuthullscrape-001

Here is an update from UGA Extension Pathologist Dr. Bob Kemerait on cutting off fungicide sprays based on our profile charts:

  1. Grower is 4 or more weeks from harvest and DOES NOT currently have disease problems in the field:
    • Suggestion – I recommend the grower apply at least one more fungicide for atleast leaf spot control.
    • Suggestion – Gen the low cost of tebuconazole, the grower may  consider applying a tank-mix of tebuconazole + chlorothalonil for added insurance of white mold and leaf spot.
    • NOTE: If white mold is not an issue, then the grower should stick with a leaf spot spray only.
  2. Grower is 4 or more weeks away from harvest and HAS disease problems in the field:
    • If leaf spot – Grower should insure that any fungicide applied has systemic/curative activity. If a grower wants to use chlorothalonil, then they would mix a product like thiophanate methyl (Toppsin M) or cyproconazole (Alto) with chlorothalonil. Others may consider applying Priaxor, if they have not already applied it twice this season.
    • If white mold – Grower should continue with fungicide applications for management of WM. If they have completed their regular WM program, they should extens the program, perhaps with a tebuconazole/chlorothalonil mix.
    • If underground white mold – Underground white mold is difficult to control. Applying a white mold fungicide ahead of irrigation or rain, or applying at night can help increase disease management.
  3. Grower is 3 weeks or less from harvest and DOES NOT current have a disease issue. Good news! This grower should be good-to-go for the remainder of the season, and no more fungicides are required.
  4. Grower is 3 weeks or less from harvest and DOES have a problem with disease.
    • If leaf spot – A last leaf spot fungicide application may be beneficial. If leaf spot if very severe, a last application will not help.
    • If white mold – It is likely beneficial to apply a final white mold fungicide. If harvest is 2 weeks away or less, then it is unlikely that a fungicide will be any benefit.
    • NOTE: If harvest is likely delayed by threat from a hurricane or tropical storm, then the grower may reconsider recommendation for end-of-season fungicide applications.
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