Consider planting peanuts in ... April?

An amazing thing is happening at Georgia’s peanut production meetings in 2013. During every presentation, University of Georgia Extension agronomist John Beasley is urging growers to plant a portion of their crop in the latter part of April to achieve top yields.

Not too many years ago, it was unthinkable to recommend planting peanuts out of a restricted window in May and early June. Planting outside that window significantly increased the risk to tomato spotted wilt virus, a disease that literally threatened peanut production in the Southeastern U.S.

Tomato spotted wilt, a virus transmitted to a number of important crops by the tiny insects know as thrips, has caused significant damage in peanut fields across Georgia, Alabama and Florida. For many years, peanut breeding efforts and implementation of production practices were squarely focused on the goal to reduce the risk for severe outbreaks of TSWV in a field.

The Tomato Spotted Wilt Virus Risk Index (now incorporated into Peanut Rx) became an important tool in the concerted effort to manage this very important disease.

At its peak in 1997, TSWV was estimated to be costing growers across the tristate area as much as 12% of their yield potential. In an effort to manage the disease, growers rapidly adopted the Georgia Green variety, increased their seeding rate to 6 seeds per foot, switched to twin-row peanuts and from Temik to Thimet, and adjusted planting dates.

One of the most important considerations has been to avoid planting peanuts in April to reduce the risk to TSWV. Such a recommendation resulted in a rapid and dramatic shift to later planting dates in May and even early June. That Dr. Beasley now notes the importance of planting some of our peanut crop in April is clear proof that we may finally be gaining the upper hand on this viral disease.

As many may recall, at the onset of spotted wilt in the Southeast, no peanut varieties were resistant to the disease. For growers today, planting seeds of TSWV-resistant varieties such as Georgia-06G and Tifguard, and using the insecticides Phorate and Thimet, have been critical in reducing yield losses associated with the disease.

Newer varieties can still succumb to the disease under high thrips and TSWV pressure. Therefore, it is still critical to use insecticides to reduce thrips-induced injuries, especially in early stages of the crop.

Researchers on the UGA peanut team have realized that time is critical to identify alternatives to Temik and Thimet usage in peanuts to effectively suppress thrips and TSWV. In recent years, a number of new insecticides with potential to manage thrips and TSWV have been released. The peanut team believes the enhanced levels of resistance in new peanut varieties provide flexibility when replacing Temik and Thimet with newer insecticides. The team has conducted research over the past two years to address this critical issue. The focus of the research has been to identify new insecticides and to evaluate their compatibility with cultural tactics such as seeding rates, row spacing and planting dates.

Babu Srinivasan and other researchers at UGA are assessing how these new insecticides can be applied at planting time more easily. Seed treatments and in-furrow applications with neonicotinoid-type insecticides such as thiamethoxam (Cruiser) and a few other new insecticides have shown tremendous potential. Some of these new insecticides have not been labeled for use in peanut yet, but both researchers and the agrichemical industry are seriously assessing this option. Within the next two field seasons, some peanut researchers at UGA are confident they will identify alternatives and include them as part of the risk management index (Peanut Rx) that growers currently use.

Kemerait is an Extension plant pathologist for UGA. Babu Srinivasan contributed to this article.

This article published in the April, 2013 edition of SOUTHERN FARMER.

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