For peanut growers in Georgia, the message is clear: “It’s game time! It’s white mold time.  Let’s do it!”

There are several important reasons why it is white mold time. First, temperatures are warming considerably as we enter the summer season. Outbreaks of white mold are more severe and are fueled by warmer soil temperatures.  Second, warm soil temperatures and moist conditions are critical ingredients for the development and spread of white mold.  Third, our peanut crop is now growing to a point where a small canopy of leaves is present.  Higher humidity and periods of leaf-wetness will increase within the canopy as it continues to expand during the season.  This warm, moist environment is essential for explosive outbreaks of white mold.

The “backbone” of white mold management remains the use of appropriate fungicides over the period between 60 and 102 days after planting.  This is our historical “white mold management block”.  However, there has been a revolution in the management of white mold over the past five years.  Not only do we have an expanding arsenal of effective fungicides for the management of white mold, such as Fontelis and Proline, but the cost of fungicide tebuconazole has dropped allowing creative new programs. 

Based largely on research from Tim Brenneman’s program, we manage white mold more aggressively.  The most obvious changes have been 1) the value of applications of fungicides at nights, 2) the value of banded applications of Proline and Abound within five weeks of planting, and 3) the value of early-season broadcast applications of tebuconazole. “Get their first with the most,” is a good strategy to manage white mold, concentrating fungicides to the target earlier than we have in the past.

How to handle white mold

University of Georgia Cooperative Extension recommendations for the management of white mold are:

  • All growers should use some fungicide program for the management of white mold over the period of 60 to 102 days after planting.  The specifics of that program is influenced by the severity of the risk to white mold (see Peanut Rx) and the fungicides that are included in the fungicide program.
  •  All growers should consider the opportunity to tank-mix tebuconazole (7.2 fl oz/A) with chlorothalonil or pyraclostrobin (Headline) early in the season. Such a tank-mix is affordable and provides a start to leaf spot and white mold control.  (Growers who will use a full-season Provost, Quash or tebuconazole program should carefully consider fungicide-resistance issues before starting the season with tebuconazole.)
  • Applying fungicides for the management of white mold at night or in the very early morning while leaves are still folded is an important tactic to optimal placement of the fungicide in the crown of the plant.  Some thought should be given to maintaining best control of leaf spot since only the underside of the leaf will be treated at night; however this is easily addressed with the use of a systemic fungicide.
  • The newest tool in the management of white mold is the use of a BANDED full-rate application of Proline (or Abound) in a narrow swath over the young peanut plants.  Depending upon weather and risk, this application can be made anywhere between two weeks and six weeks after planting.  Earlier applications are likely most effective when risk to white mold (early-season hot weather and high Peanut Rx risk value) is greatest.  Delaying the application until four-to-five weeks after planting is more appropriate in many cases and also reduces or even eliminates the need for early-season leaf spot fungicide sprays. 

Bob Kemerait is a plant pathologist with the University of Georgia Cooperative Extension.

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