Tache grise

Class: champignons
Common Name: Tache grise
Scientific Name: Cercospora zeae-maydis
Potential Host:

Corn

Who Am I?

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.

Control Measures

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.

Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.

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