White mold could easily become one of the greatest threats to peanut production in 2022.
Temperatures in southern Georgia are expected to be in the mid-to-upper 90s for the remainder of
June. Rainfall is anticipated to be sparse and scattered. Sclerotium rolfsii, the fungal pathogen that
causes white mold (more properly referred to as “southern stem rot”) thrives in hot weather. Lack of
rainfall, especially in non-irrigated fields, can make it more difficult to control white mold as rainfall or
irrigation within 24 hours after a fungicide application is important to move the fungicide from the
foliage to the crown of the plant. Protecting the crown of the plant is an important “target” for
management of white mold.
Sclerotium rolfsii can infect peanut plants at any growth stage, but causes the greatest damage when
the limbs and foliage along a row have closed. This allows the fungus to easily spread from one plant to
the next when conditions are warm and humid. Smaller plants can be affected by white mold early in
the season; however spread from one plant to the next is much more restricted.
Recommendation: Though “white mold programs” typically begin at about 60 days after planting when
the peanut canopy is larger and more at risk for disease spread, growers should consider putting
something out at 45 days after planting. I believe a more aggressive white mold program is justified this
season because of early-season conditions. Growers could initiate a “white mold” program by one of
- Mix 7.2 fl oz of tebuconazole with a leaf spot material, for example chlorothalonil.
- Use products like Priaxor or Lucento that have fair white mold activity in addition to stron leaf
- Initiate the 3-spray Elatus (7.3 oz) or Excalia (2.0-3.0 fl oz/A) programs
For several reasons beyond those mentioned above, June is a critically important month for disease
management and, sometimes, for nematode management as well. Based on planting date, most of the peanut crop will be between 30 and 45 days after planting at some point in June. Some of the below is “recycled” from last season. I hesitate to do this, but if fits again this year, so here goes….
- Fungicide programs for management of leaf spot diseases (except for the earliest and latest planted peanuts) are typically initiated during the month of June. Leaf spot programs should
begin closer to 30 DAP when A) the field is at higher risk to leaf spot based upon results from
Peanut Rx, and/or when B) fungicides to include chlorothalonil, Mazinga, chlorothalonil +
Domark, and chlorothalonil + Alto are used as the first fungicide application.
- Fungicide programs for leaf spot management can safely begin closer to 45 days after planting
when A) the field is low-risk to leaf spot diseases as determined with Peanut X, B) fungicides
such as Priaxor, Lucento, or Aproach Prima are used in the opening fungicide application, or C)
Velum or Velum Total is used in-furrow at planting.
- Growers should avoid, if at all, possible initiating a peanut fungicide program later than 45 days
- The “backbone” of most fungicide programs for control of white mold does not begin until
approximately 60 days after planting; however growers often start earlier, especially when short
rotation increases risk to disease. Effective ways to begin a white mold program within the first
45 days after plantings are to A) apply Proline (5.7 fl oz/A) in a narrow band over the peanuts, B)
include tebuconazole or azoxystrobin with your first leaf spot applications, or C) adopt Elatus or
Excalia programs that begin as early as 30 days after planting.
- Applications of Propulse can be made as early as 45 days after planting to fight leaf spot, white
mold, and to supplement earlier nematicide applications for control of nematodes.
The “Good”: Timely fungicide applications (before disease is established) are a critically important tactic for controlling disease. Starting your leaf spot program on-time, often in June, sets the stage for a successful disease management program and best yields.
The “Bad”: Getting behind in a fungicide program early in the season may allow disease to become
established that is difficult (if not impossible) to manage later in the season. While I know some growers wait until 50-55 days after planting to begin their program, I strongly advise you to not wait later than 45 days after planting and to begin as early as 30 days after planting in a number of situations.