Impact of selected cultural practices on late season and overwintering stem borer infestations in sugarcane and rice

The sugarcane borer [Diatraea saccharalis (F.)] and Mexican rice borer [Eoreuma loftini (Dyar)] are pests infesting graminaceous crops along the Gulf Coast. Experiments were conducted in sugarcane and rice to study the role of common production practices impacting late season stem borer infestations. In sugarcane, the differential impact of four planting dates (from early August to late November) on D. saccharalis infestations was assessed in a two-year experiment conducted in Louisiana. Compared with later plantings, the August planting contributed important D. saccharalis infestations towards potential major overwintering populations. In rice, the impact of harvest height (20 cm vs. 40 cm) and producing a ratoon crop on D. saccharalis and E. loftini infestations was assessed in a two-year experiment conducted in Texas. Although substantial post-harvest infestations remained in rice culms regardless of harvest height, the lower cutting height removed a greater proportion of E. loftini than D. saccharalis. During the late growing season (October), ratoon rice plots harbored more stem borers than plots that were not ratooned. However, after ratoon harvest, in January more stem borers infested non-ratoon plots, while in March differences were not detected between ratoon and non-ratoon plots. Potential new production recommendations for stem borer management in sugarcane and rice will be discussed.