Grape IPM Program: Identifying Pierce's Disease

Identifying Pierce's Disease

From summer through harvest, look for symptoms of Pierce’s disease and flag vines showing these symptoms. Vines that have had symptoms for a second year and first-year vines with extensive foliar symptoms (including tip dieback) on most canes should be removed.

Names link to more information on identification and management.

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Pierce's disease

Pierce’s disease
A common symptom of this disease is Irregular, patchy bark maturity. Note that half the shoots are brown and half are green with islands of green and brown.

In the spring, leaves on plants with Pierce's disease may show interveinal chlorosis.

Advanced late-summer or fall symptoms of Pierce's disease on foliage of a white grape variety shows concentric rings of drying from the outer edge toward the center.

Leaf margins of a red grape variety turn red and then brown when affected by Pierce's disease in late summer and fall.

Pierce's disease causes petioles of leaves to remain attached to canes after leaf fall.

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