Based on our observations the following viticulture practices could be responsible for early vineyard decline:

1) Grafting healthy plant material on to old infected trunks.

2) Grafting infected noncertified plant material onto healthy wood.

3) Replanting a new vineyard but leaving the vine stumps of the former vineyard in the ground, providing a source of disease inoculum.

A high level of production is needed for California’s table grape growers to maintain its dominant position in the marketplace but canker diseases threaten this goal.

It is critical for the industry to develop and implement a management program that supports sustainable crop productivity in order to ensure of the long-term profitability of vineyards. California researchers are working towards that goal by identifying canker causing pathogens, learning their biology and looking for manage management methods that will inhibit fungal infections.

Future research will focus on the following points working closely with the table grape industry:

1) Measure the economic impact of canker diseases in table grape production.

2) Survey additional vineyards to map the disease distribution in California’s table production areas.

3) Evaluate the long-term spray application of thiophanate-methyl on the reduction of disease incidence in young vineyards.

4) Evaluate the practice of grafting plant material and disease expression.

 

Philippe Rolshausen in a viticulture plant pathologist located at UC Riverside. Stephen Vasquez is the UC Cooperative Extension viticulture farm advisor for Fresno County. Carmen Gispert is the UC Cooperative Extension viticulture farm advisor for Riverside County.