Pierces Disease in the Vineyard
Once infected, vines will rarely live for more than two years. Symptoms include dryness and withering of vines. They are literally starved of nutrients and water. Pierces Disease affects many other plants including peach and orange trees. Avocados are also very susceptible.
The disease is named after Newton Pierce, a scientist who made major breakthroughs in understanding the blight. The first major documented outbreak occurred in the Anaheim area during the early 19th century. Over 40,000 acres of vineyards were destroyed.
Pierces Disease was first carried by the blue green sharpshooter. Because the insect was not capable of flying more than a few feet, the disease was naturally contained. The blue green sharpshooter typically only eats new shoots, and is responsible for the devastation Pierces Disease has caused in Napa and Sonoma Counties.
Unfortunately, the glassy winged sharpshooter was discovered in California in 1990. Experts believe that the sharpshooter entered the state as eggs on plants. The potential threat of the glassy winged sharpshooter is much greater than the blue green sharpshooter. It is a more formidable insect that is larger and can fly farther. It feeds on bark and wood on vines.
> Related Articles