Leafroll disease in vineyards 

Leafroll disease in vineyards    

Leafroll disease is one of the most widespread and economically damaging viral diseases of grapevines. It reduces yield, delays fruit ripening and alters fruit chemistry, which affects juice and wine quality. Leafroll disease costs New York growers between $25,000 and $40,000 per hectare, depending on the level of disease incidence and impact. While leafroll disease has been recognized as a threat to grape production for decades, management strategies to control it are still lacking.

Leafroll disease is spread by mealybugs who feed on an infected grapevine and then crawl along the vine canopy and vineyard trellis system to spread it to neighboring vines. In New York, the species that spreads it never leaves plants and never flies when carrying the virus.

Cornell University researchers investigated the effectiveness of removing the visibly infected vine as well as two vines on either side of it as a means of limiting the spread of leafroll disease. Researchers believed this strategy could provide better long-term virus control than single vine removal. Working with a New York vineyard, researchers documented leafroll virus’ presence in mealybugs and tested the effectiveness of plant removal and mealybug insecticide management, alone and in combination.

Removing the infected vine, as well as two plants on either side of it, was highly effective in reducing virus incidence quickly. Vine removal reduced virus incidence from 4% in 2016 to nearly zero by 2020-2021. Insecticides applied from 2016-2020 reduced mealybug populations to almost zero as well. Despite reductions in mealybug populations, insecticides contributed relatively little to limiting disease spread to uninfected vines.

Cornell’s research confirms that removing infected plants and adjacent plants should serve as a cornerstone for leafroll disease management.

Link to full statement on website: https://landgrantimpacts.tamu.edu/impacts/show/5666