As a team of University of California research scientists working to develop strategies that may help California grapegrowers control leafroll disease, we were very concerned about Kerry Kirkham’s article “Live with Leafroll” in the June edition of Wines & Vines. In particular, we are concerned that readers who do not know very much about leafroll disease could easily be persuaded that this problem is easily overcome in the winery by technical manipulation.

One of our challenges in educating the grapegrowing community about this problem is that growers with severe leafroll want to take care of the problem quietly so it does not affect the perception of their fruit and the wines made from it. Most individuals willing to be quoted about the problem have mild disease problems or rely on a winemaking style that minimizes any effects of the virus on the fruit.

With the help of the American Vineyard Foundation, a trial of nearly 8 acres has been undertaken at the Armstrong farm at UC Davis. Cabernet Franc has been grafted with multiple treatments of virus, on multiple rootstocks. The vineyard was planted last year; within a few years, we should have unequivocal data on the range of effects of leafroll disease on all parameters of vine and fruit as well as wine quality. We hope that will make a case for virus control and management that will be convincing to the grower community for years to come.

Dr. Rodrigo Almeida
Associate professor, UC Berkeley

Dr. Monica Cooper
Napa Valley viticulture farm advisor

Dr. Kent Daane
Cooperative extension specialist, UC Berkeley

Dr. Deborah Golino
Director, Foundation Plant Services, UC Davis

Dr. Neil McRoberts
Assistant professor, UC Davis

Dr. Adib Rowhani
Project scientist, UC Davis

Dr. Jim Wolpert
Cooperative extension specialist, UC Davis