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Around The Vineyard

Crown gall symptoms caused by A. vitis

Vineyard Bacterial and Fungal

Trunk Diseases Prevention and

Control By: Judit Monis, Ph.D., Vineyard Health Consultant
G and can be caused by bacterial or fungal Crown Gall
rapevine trunk diseases occur worldwide

pathogens, and sometimes a combination
The disease is caused by the tumor-producing
of both. Pathogenic bacterial and fungal patho- bacterial species, Agrobacterium vitis. The bacteria
gens can be found colonizing the vineyard soil. It penetrate the vines through mechanical injuries
is important to note that important trunk disease caused physical damage caused during vineyard
fungal pathogens not only affect grapevines, but operations or by freezing temperatures. The galls
also cause disease in landscape and fruit trees. are generally visible at the crown area of the plant
Grapevine stock can be infected with important but can also be found in the upper portion of the
pathogens which makes it important to screen vines and at the graft union of nursery produced
nursery material for their presence prior to plant- vines. The bacterial-induced galls cause a reduction
ing. of the flow of water and nutrients that eventually
cause vine decline and death. Although the disease
Below I describe the most common grapevine occurs more frequently in the Eastern and Mid-
trunk diseases caused by bacteria and fungi. As Western United States vineyards, I have observed
with viruses, bacterial and fungal pathogens can be vineyards severely affected by A. vitis in Californian
found in mixed infections (even viruses can be pres- vineyards. The best practice to avoid the infection
ent), exacerbating the problem in a vineyard. of this bacteria is to plant material from vineyards

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