How to Manage Pests

Pests in Gardens and Landscapes

Thinning

Many grape varieties, especially spur-pruned varieties, require shoot and berry thinning.

Shoot thinning

When shoots reach 6 to 12 inches, thin them out so that there are only two shoots to each spur or to each bud position on the cordon.

Berry thinning

The berry clusters also often need to be thinned to allow fewer but larger berries to form. Just after bloom and berry set, remove the lower third of the clusters or cut alternate side branches of the cluster.

Grape shoots
Six-inch shoot growth stage

Grape thinning
Thin after bloom and berry set


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