INTRODUCTION
Crown gall on grape, caused by the bacterium Agrobacterium vitis, occurs throughout the world where grapes are grown. In Pennsylvania and New York, crown gall can lead to vine decline and mortality in vineyards (Stewart & Wenner, 2004). Grapevines grown in areas subject to freezing winter temperatures are especially vulnerable to crown gall because freeze injuries provide a wound where the disease can initiate.
The crown gall pathogen survives systemically within the grapevine and causes disease at wounded areas on the vine (Lehoczky, 1968). There are both tumorigenic and nontumorigenic strains of A. vitis found on grape (Burr et al, 1998). Tumorigenic strains are detected only in soils that have been used to grow grapes and can induce infected vines to develop large galls at, above, and/or below the soil line. Nontumorigenic strains can be found on the roots of wild vines and have not been associated with gall formation. Tumorigenic strains of A. vitis are initially introduced into new vineyard soils by planting infected nursery stock.
Fruit Characteristics Chart
Plant Troubleshooting
Field Notes
