UC Delivers

IPM program helps North Coast growers in fight against Virginia Creeper Leafhopper

The Issue

Virginia creeper leafhopper (VCLH) first arrived in California's Sacramento Valley and Sierra Foothill regions in the 1980s. It was recently introduced into the North Coast, where a lack of biological control led to severe outbreaks in 2011-2012. The native Western grape leafhoppers are typically controlled well by native parasitoids. When chemical controls are necessary, applications occur later in the season, in August. In the absence of biological control, chemical controls for VCLH were required, needing to go on earlier in the season, in May or June. When the first outbreaks of VCLH occurred, many growers responded by putting on multiple late season sprays to little effect. Some certified organic growers resorted to conventional pesticides and lost their organic certification.

What Has ANR Done?

In 2012 UC ANR Advisors identified the leafhopper outbreaks as VCLH and studyied its biology and control. They brought together a team of UC scientists, growers, pest control advisors, and other industry stakeholders, establish the “Area-wide IPM Program for Virginia Creeper Leafhopper” in 2014. The program's short- and long-term objectives sought to stem the ongoing outbreaks and reestablish biological control of VCLH. Field days and seminars educated growers on VCLH identification, seasonal ecology, and management. A regional monitoring effort also provided growers with a weekly email update on VCLH life-cycle and population development across Mendocino and Lake Counties. Spray trials were conducted to refine product selection and timing for organic growers. Additional information can be found at http://ucanr.edu/sites/VCLH and http://ucanr.edu/blogs/LeafhopperBlog. A survey for VCLH parasitoids was conducted across northern California, leading to the identification of a population of the VCLH egg parasitoid, Anagrus daanei, in the Sacramento Valley. A pilot release of these parasitoids into a North Coast vineyard resulted in increased VCLH parasitism and a large-scale rear-release program was initiated. From 2015-2017, more than 30,000 A. daanei were released into Mendocino County and Lake County vineyards. The full impact of this release program will become apparent in the long term.

The Payoff

ANR program results in improved identification and management of VCLH pest

Growers are now well-trained in the identification and management of VCLH, resulting in improved spray timing and reduced frequency of applications. The project website continues to serve as a resource for growers. Ongoing regional monitoring efforts are announced through the Leafhopper Blog. Annual trends indicate that VCLH parasitism is increasing across the region, especially at the end of the season. In some cases late season VCLH parasitism occurs at sites where no parasitoids were introduced. Genetic evaluations are underway to determine whether or not these are the same parasitoids that were introduced. The colony of A. daanei is maintained at UC Berkeley and additional introductions may take place in the future.

Contact

Supporting Unit: Integrated Pest Management (IPM) Statewide Program

Lucia Varela, North Coast Area IPM Advisor, UCCE, lgvarela@ucanr.edu

Glenn McGourty, Viticulture & Plant Science Advisor, UCCE Mendocino County, gtmcgourty@ucanr.edu

Houston Wilson, Asst. CE Specialist, Kearney Agricultural Research and Extension Center, houston.wilson@ucr.edu