Foliar Chemical Protection Against <i>Pantoea ananatis</i> in Onion Is Negated by Thrips Feeding

Center rot of onion, caused by Pantoea ananatis, is an economically important disease in onion production Georgia and elsewhere the United States. Growers rely on frequent foliar applications bactericides and, some cases, plant defense inducers to manage this disease. However, regular prophylactic application these chemicals not cost-effective may be environmentally friendly. Thrips (Thrips tabaci Frankliniella fusca) are vectors P. their feeding compromise effectiveness against ananatis. In study, treatments with acibenzolar-S-methyl (Actigard 50WG), cupric hydroxide (Kocide 3000), Actigard plus Kocide were evaluated for presence absence thrips infestation at two critical growth stages: bulb initiation swelling. Onion stage had no impact either or Actigard. thrips, resulted reduced center incidence compared Actigard, regardless stage. when present, efficacy both was reduced, significantly different from nontreated control. independent greenhouse studies it observed that use protective (Kocide, combinations) rates also affected pathogen progression into internal neck tissue rot. These results suggest can reduce chemical foliage resulting scars could facilitate ananatis entry subsequently treatments. Therefore, effective management strategy should likely include addition susceptible stages onion.