How to Manage Pests
UC Pest Management Guidelines
Bot canker causes death of arms, cordons, and vines. The wedge-shaped, darkened cankers that develop in the woody vascular tissue are indistinguishable from Eutypa dieback. Unlike Eutypa dieback, there are no foliar symptoms.
Bot canker is a pruning wound disease commonly seen in vines 10 or more years old. Pycnidia, spore-producing structures produced on surface of canker, provides inoculum for infection. Bot canker is the major cause of arm and cordon death statewide and is most prevalent south of Madera County.
If your table grape vineyard has a history of Bot canker, look for symptoms of poor budbreak in spring and for damage symptoms in late summer or fall.
Pruning wounds provide an infection site. Once infected, complete removal of canker is necessary. On older vines, doubling of spurs to replace lost spur positions and extensive cordon retraining is necessary to maintain production. Cultural practices, such as proper water and fertilizer management and good pruning techniques, designed to maintain vine vigor are necessary and may enable the vines to outgrow infections by this organism.
UC IPM Pest Management Guidelines: Grape