Winter covers, planting dates and cultivar influence on diseases and nematode pests of peanut in a rainfed production system

Peanuts (Arachis hypogaea L.) are a valuable crop in Alabama that is vulnerable to tomato spotted wilt (TSW), stem rot (SR), and the peanut root-knot nematode (PRKN, Meloidogyne arenaria Race 1). Winter co-vers are widely employed in Alabama strip or no-till peanuts to suppress erosion and runoff as well as en-hance moisture retention and carbon sequestration. Adjusting planting dates for disease avoidance along with disease and nematode resistant cultivars help maximize yield and reduce input costs. Here, the influence of the cereal winter covers (oat, rye, and wheat) along with a weed fallow was evaluated on the above diseases and nematode pest, as well as yield components, in the following peanut crop on a rainfed site with resident M. arenaria and Agroathelia (Sclerotium) rolfsii (SR) populations. The impact of April or May planting dates along with the PRKN-resistant Tifguard and susceptible Georgia-09B cultivars, both of which are partially re-sistant to TSW, and any interactions were assessed annually from 2014 to 2018. Superior yields were often obtained for peanut cropped behind a rye or weed fallow compared with oats and wheat. Except for oats in 2017 and 2018, pod grades did not significantly differ by winter cover. In addition, winter cover had limited effects on TSW and SR indices, root and pod galling (RKDam) and M. arenaria juvenile populations (RKPop) in the following peanut crop. While yield was greater for April than May peanut plantings for the 2017 and 2018 study period, May plantings had superior yields in 2016 with similar yield reported for both plantings in 2014 and 2015. Higher grades were noted for May than April plantings in only one of five years with similar grades for both plantings recorded for the remaining four years. Planting date had limited impact on TSW and SR indices along with RKDam and RKPop. Georgia-09B often suffered greater SR than Tifguard. In addition, the resistant cultivar Tifguard had significantly less RKDam along with lower final PRKN juvenile popula-tions compared with the susceptible Georgia-09B. Because of reduced SR, RKDam, and RKpop, Tifguard pro-duced significantly greater yield than Georgia-09B. Except for 2015, Tifguard and Georgia-09B had similar grades. Therefore, the PRKN-resistant Tifguard consistently produced significantly greater yield often with less damage attributed to SR along with PRKN in a rainfed production system compared with the susceptible Georgia-09B with a rye or weed fallow being the preferred winter cover for optimizing yield of strip-till peanuts.