Powdery Mildew of Grapevines Alert


This disease usually appears on the upper surfaces of leaves as white-grayish spots with a powdery-like texture, while the underside of leaves often appear brown. The infection can occur on both upper and lower leaf surfaces.

Who Am I?

Erysiphe necator is a fungal disease that grows only on grapevine tissue. The disease is host-specific, which means that certain pathogens can only infect plants from the same genus or family. In this case, powdery mildew of grapevines can only infect grapes.

Control Measures

Monitoring: Make it a routine to monitor the field regularly and search plants for the presence of powdery mildew on a weekly basis. It is easier and more cost effective to overcome the infestation by controlling it during the initial stage.

It is a common practice to prevent powdery mildew by spraying early in the season on the basis of the growth stage of the vines, namely somewhere around 10-15 centimeters of green vegetative growth.

Consider an application of fungicides every 7-14 days until the grapes have finished changing their color.

Consider an extra application when infected plants have been observed, which is common even under a heavy spraying regime.

Sulfur (dust, wettable, flowable, or micronized) and potassium bicarbonate

Bacillus pumilis and bacillus subtilis

*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.

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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