Gray leaf spot is a major fungal disease of corn found throughout the world. Previously diseased corn plant debris and leftovers from previous seasons are the primary sources of the infestations. Additionally, spores from adjacent infected fields can be carried by the wind causing infestations.
Infection can occurs after prolonged warm and moist conditions. The demand of biofuel resulted in a rise of monocrop fields, which means that corn is grown on the same land year after year, season after season. Continuously growing corn on poor land preparation causes gray leaf spot to become a serious disease in some countries.
Lower leaves are usually the first to catch the disease; 12-14 hours of leaf wetness is enough to initialize infections. With time, rectangular necrotic lesions form between leaf veins. Lesions are initially tan or brown in color.
The economical impact depends on when in the season leaves become infected. In the majority of cases, significant yield losses occur when ear leaves or leaves above the ear exhibit signs of the infection prior to the pollination time, which is the key time of the season. Ear leaves are the “driving force” of plant activity; they are the primary absorbers of light, thus losing these leaves damages kernel development and affects expected yields.
In severe cases, when all leaves above the ear are lost, the plant will cannibalize its available sugars. This impacts the strength of stalks and makes them vulnerable to other pathogens.
Utilisez des variétés de plantes et des semences résistantes à la maladie.
Technique de perturbation de l’accouplement : Utilisez des dispositifs spécialement conçus, tels que des phéromones sexuelles synthétiques, qui perturbent le processus d’accouplement en déroutant les hommes. Cela peut réduire considérablement le besoin d’applications d’insecticides.
Calendrier: Il est plus facile et plus rentable de surmonter les infestations au cours des premières étapes. Surveillez régulièrement le champ et recherchez les signes ci-dessus.
Les produits utilisés dans une ou plusieurs régions du monde peuvent contenir les ingrédients suivants :
pyrachlostrobine, cyproconazole, prothioconazole, metconazole, tebuconzole fluxapyroxad, propiconazole, azoxystrobine, trifloxystrobine, picoxystrobine, chlorothalonil, et mancozèbe.
*Names marked in red are considered to be highly poisonous to beneficial insects.
*Names marked in green are considered to be organic and IPM (integrated pest management) compatible.