Phlloxera infestations were reported in the Salinas Valley of Monterey County for the first time in July 1983. One of the first two affected vineyards contained several scattered regions of dead or depressed vines ranging in size from a few vines to a few hundred vines each. When and how the phylloxera insects were introduced is not known. Small areas of vine depression were later detected on aerial photographs taken as early as 1981. Color infrared aerial photographs taken in 1983 and 1984 showed 8% and 30%, respectively, of vines in a 26-acre block were depressed by phylloxera, compared to 0.5% in the 1981 photograph. This rate of increase is about 381% per year. Projecting the rate forward, all vines should be dead or depressed in 1985. Projecting the rate rearward, the infestation could have started in 1978 or earlier from a single point infestation. For the first three to four years, it was too limited to detect, but in the following four years the entire vineyard block has been infested.
- Copyright 1986 by the American Society for Enology and Viticulture