(Wines&Vines) - Based on data released from the California Department of Pesticide Regulation (DPR) in its annual Pesticide Use Reports (PUR) through 2014 (the latest year of available data) for California wine grape acreage, use of fungicides (including sulfur) and herbicides from 2010 through 2014 indicated relatively similar annual use levels during this period, while the use of insecticides for the same period showed a slight increase. These trends are attributed, in part, due to drought conditions that reduced weed growth and reduced pressure from powdery mildew and fungal pathogens. However, milder winter and spring weather with higher temperatures increased insect pest pressure as more generations of vineyard pests were able to reproduce and required a greater number of insecticide applications.

Pesticide Use Report data

During the five-year period from 2010 to 2014, overall planted acres of wine grapes increased (based on data sources used by DPR) from 535,000 acres in 2010 to 615,000 acres in 2014. For the purposes of reporting data, DPR’s figures for total acres treated includes the cumulative number of acres treated with pesticides during the year. Thus, the number of acres treated can be higher than the number of acres planted due to the fact that many growers make multiple applications on the same acreage during the growing season.