Management of Pod Rot of Peanut

Issue: Peanut producers in the High Plains of Texas have a difficult time deciding when to treat for pod rot. Ideally, fungicides to protect pods would be applied before pod rot begins, and applications would only be made to the areas of the field which are going to have a significant pod rot problem. However, pod rot does not occur every year, and pod rot does not begin at the same time of the year, even when it does occur. As a result recommendations are very vague on pod rot management and producers either don't apply pod rot fungicides in a timely manner (and suffer a loss to their crop value), or they apply fungicides before pod rot is a problem and then have years when the fungicide application was unnecessary due to no disease.

What has been done/discovered: A circle located in Gaines county which has been donated for use by the Western Peanut Growers Association was irrigated so that some sections received 100 % ET (replacement of water which was removed through evaporation), some sections received 75 % ET, and some sections received 50 % ET. What we learned, was that irrigation did affect pod rot, where the 50 % ET lost about 3 % of the pods to rot, and the 75 and 100 % ET areas lost about 8 - 9 % of the pods to rot. We did not expect the 75 % ET to have as much pod rot as the 100 % ET, but there was sufficient water at 75 % ET to initiate significant pod rot. We also learned that some positions in the field had much less pod rot, regardless of irrigation treatment than other positions in the field. In this case the more northern positions, which were higher in altitude, and may have drained the water away quicker, had much less pod rot than the more southern positions. The northern positions averaged between 0 and 5 % pod rot, while the southern position averaged between 1 and 27 % pod rot. This means that how quickly the soil drains water should be a good predictor to severity of pod rot. Developing soil water maps of a field should allow producers to sample those areas most prone to pod rot first, and allow for more timely application of fungicides.

Impact: Fungicide applications in peanuts to protect against pod rot can be costly. Each application may cost between $15 and $50/acre. Knowing what part of the field to treat (instead of treating the entire field) can result in substantial savings. The second economic factor is that delay in application of fungicides after pod rot has begun also leads to loss in peanuts that can be sold. Underground diseases like pod rot can cause very high losses (15 % in one test field in 2001) before the producer is even aware of a problem. Knowing where to look for pod rot first can save much of this loss.

Funding Sources: Precision Agriculture State Initiative and Western Peanut Growers Association

Contact:
Terry Wheeler
Associate Professor
Research & Extension Center - Lubbock
Texas A&M Agriculture Program
Phone: 806-746-4014
Fax: 806-746-6528
ta-wheeler@tamu.edu
http://precag.tamu.edu