Peanut Response to Injury Caused by Tobacco Thrips and Pesticide Combinations

Thrips (Frankliniella spp.) can reduce peanut (Arachis hypogaea L.) yield by injuring peanut tissue and by vectoring tomato spotted wilt orthotospovirus (family Tospoviridae, genus Orthotospovirus). Pathogens early in the cropping cycle can cause disease, and weeds that escape herbicide applications prior to or at planting can interfere with crop yield if not controlled. To suppress these pests, farmers often apply pesticides either individually or as tank mixtures. For logistical reasons when pests are present at the same time, farmers would prefer to apply pesticides simultaneously. Three different experiments were conducted from 2012-2017 in North Carolina to determine peanut response to herbicides as a result of injury caused by tobacco thrips (Frankliniella fusca Hinds) or the implications of co-applying herbicides with insecticide or fungicide to suppress this insect pest and protect peanut from disease. In one experiment, stunting of peanut caused by a combination of injury from paraquat plus bentazon alone or with S-metolachlor and feeding by tobacco thrips was not affected by co-application with the fungicide prothioconazole. In a second experiment, stunting of peanut by co-application of the herbicides lactofen plus bentazon plus 2,4-DB or lactofen plus imazapic plus 2,4-DB alone and with S-metolachlor was not affected by thrips injury in presence of the insecticide phorate applied in the seed furrow at planting or when these herbicides were co-applied with acephate. In a third experiment, peanut stunting after co-application of acetochlor or pyroxasulfone was not affected when phorate was applied in the seed furrow at planting or when these herbicides were co-applied with acephate. Peanut yield was not affected by injury caused by herbicides applied alone or with acephate. However, in most cases peanut yield was greater when phorate was applied in the seed furrow at planting as a result of thrips suppression by this insecticide regardless of herbicide or acephate treatment following peanut emergence. Acephate did not affect yield regardless of co-applied pesticide or phorate treatment at planting