American gooseberry mildew (Sphaerotheca mors-uvae) – identify and control

The American gooseberry mildew, Sphaerotheca mors-uvae is a fungal disease native to America, being first observed and described in 1833. This disease also attacks clove plants, blackcurrant, redcurrant, and mountain currant.


Symptoms.
The fungus Sphaerotheca mors-uvae attacks the leaves, young shoots, and fruits. On the leaves appear whitish spots, formed by the mycelium of the fungus, visible on both sides. The leaves remain small, and the white powdery growth on their surface acquires a dusty appearance due to the formation of spores. The leaves fall, the plants grow abnormally, produce little fruits, and the frost resistance of the stems is reduced.

The attack on the fruit is similar to that on the shoots. The young fruits turn black and shrivel up, the more advanced fruits have whitish, then gray-brown spots, in which the tissues will necrotize and the whole fruit is covered with a dry or wet mold (depending on the atmospheric humidity). During the summer (July-August), the whitish mycelial patches acquire a gray-brown coloration, due to the formation of a large number of fruiting resistance with spores.

The pathogen. The wintering of the Sphaerotheca mors-uvae fungus is carried out by the resistance mycelium located in the shoots and buds or by the cleistothecia. The American gooseberry mildew is greatly favored by the excess moisture and the presence of spores spread by the wind.

Prevention and control. In plantations, it is recommended to cut the attacked shoots and burn them, as well as to bury the attacked leaves under the furrow, by deep plowing. During the growing season, it is recommended to apply treatments with specific fungicides.

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American gooseberry mildew (Sphaerotheca mors-uvae) – identify and control
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