How Late Can We Plant Peanut?.

For many years peanut, Arachis hypogaea L., was planted between April 15 and May 25 in the southeastern United States. This correlated with more desirable climatic conditions, particularly soil temperature and moisture. In the late 1980’s and early 1990’s tomato spotted wilt tospovirus became a major yield limiting factor of peanut. Previous research indicated the severity of tomato spotted wilt virus was much greater on peanut planted during the earlier time frame of the traditional planting window. To avoid the higher risk of tomato spotted wilt virus on early planting, producers shifted to later planting dates when the risk was not as high. Later planting caused logistical problems with cotton harvest and the risk of cold weather shutting down peanut maturation before optimal yield potential. Several cultivars that have been released over the past few years have a significantly higher level of resistance to tomato spotted wilt virus compared to the cultivars that were being planted. The objective of this research was to determine if these recently released cultivars with increased levels of resistance to tomato spotted wilt virus could be planted earlier without suffering the negative impacts of tomato spotted wilt virus. Another objective was to determine how late can peanut be planted in south Georgia without risking the negative impacts of cold temperatures on maturity and yield potential. Trials were conducted in crop years 2004-2008. Eight runner-type cultivars were planted at several locations in Georgia in a split plot design with four replications. Planting date served as the main plot and cultivars as the sub-plot. Plot size varied with location. Planting dates were late April and late May or early June. The most dramatic response was with tomato spotted wilt virus. There was a significant reduction in tomato spotted wilt severity in the late May planting date, especially in cultivars that were more susceptible to the virus. Cultivars that were more susceptible to the virus has a significant yield increase as planting date was delayed from late April to late May. Cultivars with a higher level of resistance to the virus had a reduction in the virus at the later planting but yield response did not always increase at a significant level. In 2006 and 2008 minimum air temperature reached in the 35 F range by October 20 and 28, respectively. The average first frost date for south Georgia is November 15. As a result of these findings, producers that need or want to plant earlier should plant cultivars with the higher level of resistance to tomato spotted wilt virus and planting in late May or early June is a risk for freeze damage.