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Grape

Identifying Flagging Symptoms

During rapid shoot growth look for flagging (wilting) shoots or shoot tips. If flagging is found, try to determine if it is due to branch and twig borer, Botrytis, or powdery mildew.

Names link to more information on identification and management.

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Branch and twig borer
Branch and twig borer
Identification tip: Wilting shoots may indicate branch and twig borer activity (if it is accompanied by a hole at the base of the shoot).

Botrytis
Botrytis bunch rot
Identification tip: If you see wilting, look for a lesion at the node of the shoot. Try to break or cut the shoot in the region between the flaccid areas and the adjacent area with normal turgor. Brown discoloration on the cut surface is evidence of Botrytis.

Powdery mildew
Powdery mildew
Identification tip: Newly emerging shoots displaying malformed foliage, stunting, and a white powdery or dusty appearance indicate an overwintering bud
infection by powdery mildew.


Statewide IPM Program, Agriculture and Natural Resources, University of California
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