The weather this spring is different than any that we have seen in quite a while. From now through planting it will be critical to watch the weather closely and base your peanut disease management decisions on the weather patterns we are experiencing. Here are some thoughts from Extension Pathologist Bob Kemerait on this topic.
Above-average temperatures throughout most the 2012-2013 winter seemed to indicate that growers could expect the same early-season warm (hot?) soil temperatures experienced in 2011 and 2012. Hotter soil temperatures early in the season increase the opportunity for the white mold pathogen, Sclerotium rolfsii, to become active and for outbreaks of white mold to develop more quickly. It is during such conditions that growers are most likely to enjoy benefits from initiating their white mold program prior to the more traditional date of “60 days after planting”. Where risk to white mold is greatest, for example short rotations, a history of white mold in the field, and warmer –than-normal soil temperatures, the banded application of Proline should have a significant advantage over broadcast applications of tebuconazole. In recent studies, the benefit from the banded application of Proline has been greater for applications made as late at five weeks after planting as compared to three weeks after planting; however the best timing is likely affected by how warm the temperatures are. For example, in a high-risk field with very warm soil temperatures, there may be some advantage to applying the fungicide earlier than five weeks after planting.
Over the past month, our weather in Georgia has become cooler and wetter than in recent years. This reversal from warmer-than-normal to cooler-than-normal may have a significant impact for our growers. Whereas I have been concerned about the threat from early-season white mold, should soil conditions stay cool and wet, the greater threat to some growers will be from Cylindrocladium black rot (CBR).
From now and through planting, peanut growers in Georgia should consider general weather conditions. If conditions remain cooler and wetter, growers planting into fields with a history of CBR should consider an IN-FURROW application of Proline (5.6 fl oz/A) or fumigation with metam sodium/Vapam (10 gla/A) rather than an early-emergence application of Proline or Abound. However, I believe that the tank-mix of tebuconazole with early leaf spot applications is effective enough and inexpensive enough that growers should still consider this application regardless of early-season soil conditions.