Virginia Creeper Leafhopper Invading California Vineyards

The Virginia creeper leafhopper (VCLH), known scientifically as Erythroneura ziczac, has been found in vineyards from the Oregon border to the northern Sacramento Valley, but as of March 2013, it has not made its way to the vineyards of Napa or Sonoma counties. However, VCLH has been found in neighboring Lake and Mendocino counties, primarily in backyard and organic vineyards (1).

This newcomer is already common in Ohio, the rest of the Midwest, and some of the east. It is more damaging than the western grape leafhopper. If left untreated, VCLH may cause complete defoliation.

For information on how to differentiate leafhopper species, and to view the life stages and damage caused, view the UC video (2).

In many parts of California, natural enemies (such as parasitic wasps) have been able to control western grape leafhoppers. A complex of Anagrus wasps lay their eggs in leafhopper eggs (3). When the larvae hatch, they feed on the eggs, destroying them. The species of Anagrus (A. erythroneurae) that is present in California now, however, does not appear to parasitize the eggs of the VCLH, but a full investigation of biological control species has not yet occurred. Anagrus daanei is a species that prefers VCLH; it has not been as effective because it lacks a species that can host it over the winter. A third species, Anagrus tretiakovae, parasitizes eggs of both types of leafhoppers. Unfortunately, it is not known to be in California at this time (2).

Cultural Controls

Cultural controls are of utmost importance for this pest because it is still unknown what spray materials might be effective in organic vineyards.

Remove basal leaves in early June when the eggs are hatching. This technique has been shown to reduce VCLH populations by as much as 70 percent with little impact on grape quality (2).

Plants that are well-fed and watered are also generally more resistant to leafhoppers. However, over-fertilization can be a problem so it is important not to stress the vines. Encouraging diverse vegetation around vineyards such as hedgerows and riparian areas can help beneficial organisms find habitat. Use sticky tape in hot spots to help with control (2).

Proper monitoring is important to determine which leafhoppers are present, where, and how many. It is unknown how many leafhoppers will cause enough economic damage to be worth controlling, but setting up a sampling plan for both the pest and beneficial organisms will help give growers and pest control professionals enough information to make decisions about controls (4).

References

1. Boyd, Vicki. “New leafhopper pest found in California vineyards.” The Grower. 09 Nov. 2012. http://www.thegrower.com/news/New-leafhopper-pest-found-in-California-vineyards-178148591.html.

2. Mitham, Peter. 2009. “Allow parasites to control leafhopper.” Good Fruit Grower. December 2009. http://www.goodfruit.com/Good-Fruit-Grower/December-2009/Allow-parasites-to-control-leafhopper/.

3. Warnert, Jeannette E. “New pest found in California vineyards.” Blog. 13 Nov. 2012. http://cesonoma.ucanr.edu/?blogtag=Virginia%20creeper%20leafhopper&blogasset=9611.

4. Wright, Larry. “Sequential Sampling Program for Grape Leafhoppers: A Method for Making Pest Control Decisions.” http://www.goodbugs.prosser.wsu.edu/Leafhopper%20Sampling%20Plan.pdf.

 

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