Effects of Hybrids, Foliar Treatments, and Infection Conditions on Bacterial Leaf Streak of Sweet Corn

Abstract

Bacterial leaf streak (BLS) of corn caused by Xanthomonas vasicola pv. vasculorum was first reported in the United States in 2017. The biology and management of BLS are poorly understood. The objective of this work was to determine the effects of hybrid, foliar treatments, and infection conditions (timing, temperature, inoculation site) on BLS of sweet corn. Field studies were conducted to determine if hybrid or foliar disease management treatments influenced BLS development and yield. Corn leaves were inoculated in plots with X. vasicola pv. vasculorum, and noninoculated plots were used for comparison. The leaf incidence and severity of BLS differed significantly among sweet corn hybrids, suggesting different levels of susceptibility to BLS. Grain yield was significantly reduced (14.7%) by BLS for one hybrid. The corn growth stage at time of infection influenced BLS, with incidence and severity significantly greater following inoculation at stage V6 than V9. Foliar application of Kocide®, LifeGard®, and Kocide®+LifeGard® significantly reduced leaf severity compared to nontreated controls in field studies. Kocide® significantly reduced leaf incidence, but no treatments significantly increased yield vs. controls. In comparisons of inoculation methods in a growth chamber, lesion length on leaves was significantly greater on stalk-inoculated than leaf-inoculated plants. Lesions developed on leaf-inoculated plants only at inoculation sites whereas lesions developed on stalk-inoculated plants on multiple leaves. In controlled environments, lesion length on leaves was significantly greater at 21°C than 27°C and 32°C. This study expands our understanding of factors that influence development and management of BLS of sweet corn.