Pierce’s disease affects vines especially in California and the rest of the United States. But it exists also in South America. The disease is spread through insects called sharpshooters. It is difficult to cure and the vines usually die within five years. Now, the University of California Davis has released five new grape varieties that have very good resistance to the costly Pierce’s disease. (The picture does not show a sharpshooter.)
The grape varieties have been developed at the university by crossing Vitis vinifera grapes with the American Vitis arizonica, which carries a gene for resistance to Pierce’s disease. It was not just a matter of one crossing. The researchers selected the off-springs that had inherited the resistant gene and crossed these again with Vitis vinifera, not just once but several times.
All of this has taken around 20 years and has resulted in four grape varieties that are 97% Vitis vinifera but with high resistance to Pierce’s disease. The grapes are called:
- Paseante Noir,
- Errante Noir,
- Ambulo Blanc,
- Camminare Noir and
- Caminante Blanc.
It is not yet known how, or if, the Californian wine producers will welcome these new varieties. (This is similar to what could be achieved with gene technology in less than 20 years, where a specific gene giving resistance could be transferred. This, however, is not accepted in the wine world today.)
Read more about new grape varieties in California here: UCDavis