Remote evaluation of maize cultivars susceptibility to late wilt disease caused by Magnaporthiopsis maydis

Restricting maize late wilt disease (LWD), which is considered a major problem for commercial production in Israel, Egypt, Spain, and other countries, requires continuous efforts in developing novel strategies to study the pathogen and its host plant interactions, to monitor its spread and to contain its devastating impact. Despite recent years' encouraging success in developing agrotechnical, chemical, and biological control strategies, today's most environmentally-friendly, efficient, and cost-effective way to restrict the disease-causal agent, Magnaporthiopsis maydis, is to use highly resistant maize genotypes. The recent discovery of highly aggressive isolates of M. maydis that may threaten resistant maize cultivars is forcing researchers and farmers to increase programs for breeding resistant maize germlines and improve our ability to identify and nurture them. The current study offers remote sensing for evaluating maize cultivars' sensitivity to LWD based on the high-resolution, visible-channel, green-red vegetation index (GRVI), and thermal aerial imaging. A commercial field having a long history of M. maydis infestation was chosen to assess 12 fodder maize genotypes with different degrees of susceptibility to LWD. Visible and thermal aerial imaging during the growth season paralleled the disease progression evaluated by molecular monitoring of the pathogen DNA inside the host plants and the plants' growth parameters and yield at the end of the season. This remote technique to evaluate the cultivars' resistance/sensitivity to LWD may enable scanning and assessing a large group of plants simultaneously, discovering early symptomatic plants, and identifying hot spots in the field with intensive disease bursts. The method also allows to detect field-environmental structure and cultivation variations that may affect the disease severity. An examination of the nutritional values of highly resistant and highly susceptible genotypes - revealed that LWD manifested the most in a significant decrease in the plants' wet weight and less in changes in their nutritional values. No significant effect was found on nutritional values for the pathogen's latent presence in resistant maize plants.