A website from UGA Cooperative Extension

A common peanut question has been concerning late season fungicides. In short, apply fungicide earlier due to forecasted rain as apposed to later due to conditions being to wet to get a tractor in the field. With peanut disease its better to be proactive than reactive. Dr. Kemerait UGA Plant Pathologist notes that when Georgia-06G drops more than 50-60% of its leaves, it’s probably time to get the plow ready no matter what the maturity board says. Below are more late season fungicide considerations from Dr. Kemerait: 

Grower is 4 or more weeks away from harvest and currently has excellent disease control.
• Suggestion – I recommend the grower apply at least one more fungicide for leaf spot
control with an inexpensive white mold material mixed with it, for good measure. It is
generally helpful to use a mix of a protectant leaf spot fungicide (like chlorothalonil)
mixed a leaf spot fungicide with some curative activity (e.g., Alto, Domark, Topsin) for
best protection.

• Suggestion – Given 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.
o NOTE 1: If white mold is not an issue, then the grower may stick with a leaf spot
spray only.
o Note 2: If grower has planted Georgia-06G or Georgia-12Y and the plants are
leaf spot-free at 4 weeks prior to the anticipated digging date, an additional
fungicide application for leaf spot may not be needed if grower is willing to
watch/scout the field for other disease, for example peanut rust, and put a
fungicide out if harvest is unexpectedly delayed, as with the approach of a
hurricane.

Grower is 4 or more weeks away from harvest and has disease problems in the field.
• If the problem is with 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 (Topsin M) or cyproconazole (Alto), with the
chlorothalonil. Others may consider applying Priaxor, if they have not already applied
Priaxor twice earlier in the season. Provost Silver from Bayer Crop Science has become
a “go to” product for helping to protect peanuts from leaf spot diseases late in the
season. Provost Silver is NOT a “silver bullet” but it has performed very well. A tank-mix
of Provysol + tebuconazole may also be appropriate.
• If the problem is white mold – Grower should continue with fungicide applications for
management of white mold. If they have completed their regular white mold program,
then they should extend the program, perhaps with a Fontelis, Provost Silver, or
tebuconazole/chlorothalonil mix. If the grower is unhappy with the level of control from
their fungicide program, then we can offer alternative fungicides to apply. Where white
mold AND leaf spot are late-season problem, then adding a little extra to the Fontelis for
additional leaf spot control may be beneficial.
• If the problem is 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 to increase management of this disease.

Grower is no more than 3 weeks away from projected harvest and does not currently 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. SEE NOTE BELOW ABOUT HURRICANES

Grower is 3 or fewer weeks away from harvest and has a problem with disease.
• If leaf spot is a problem and 2-3 weeks away from harvest, a last leaf spot fungicide
application may be beneficial. If leaf spot is too severe (more than 25% defoliation
already occurs), then a last application will not help. Tank mixing chlorothalonil with a

systemic fungicide, like thiophanate methyl, Domark, or other appropriate systemic
fungicide, could be beneficial.

• If white mold is a problem and harvest is 3 weeks away, then it is likely beneficial to
apply a final white mold fungicide. If harvest is 2 weeks or less away, then it is unlikely
that a fungicide will be of any benefit.
o NOTE: If harvest is likely to be delayed by threat from a hurricane or tropical
storm, then the grower may reconsider recommendations for end-of-season
fungicide applications.

Pics from this week:

Nematode galling on cotton roots.
TSWV on peanut hull.
TSWV on peanut. Has a “water stain” appearance.
Board says 7 days, vines and stems in good shape, nothings turning loose in hulls, let them sit but make sure digger is ready.
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