VCLH nymphs began to emerge on May 14th, 2018
This season we will once again be monitoring the development of Virginia creeper leafhopper, VCLH, (Erythroneura ziczac) and Western grape leafhopper, WGLH, (Erythroneura elegantula) populations in Mendocino County Chardonnay vineyards. The monitoring efforts this year will be limited to three different locations in Mendocino County where known populations of Virginia creeper leafhopper occur (Hopland, McDowell Valley and Talmage). We plan to provide information regarding egg deposition and nymph development of these leafhopper species at key times this growing season.
Virginia creeper leafhopper and Western grape leafhopper continued laying eggs on basal leaves (see Figures 1 & 2). Monitoring efforts during the week of May 14th showed the first emergence of VCLH nymphs for the season (see Table 1 for # VCLH nymphs per leaf for May 24). Nymph emergence will continue to increase in the coming weeks. We will monitor the number of nymphs per leaf going forward this growing season.
Due to the lack of biological control, effective early-season control of VCLH is critical. Based on monitoring, if control measures are needed, the optimum application period would be when the majority of the population is still in the younger nymphal stages before the emergence of adults. This is especially important if you plan to spray with an oil. Depending on population levels at your site, a follow-up application may be required to impact nymphs that emerge after the spray. Consult your PCA for materials, rates and timing.
Figure 1. Average number of Virginia creeper leafhopper eggs per leaf at three locations in Mendocino County.
Figure 2. Average number of Western grape leafhopper eggs per leaf at three locations in Mendocino County (Note: the y-axis scale is different from previous graph).
Table 1. Average number of Virginia creeper leafhopper nymphs per leaf at three locations in Mendocino County on May 24th, 2018.
Location | Average # of VCLH nymphs/leaf |
Talmage 1 | 1.9 |
Hopland 1 | 0.1 |
McDowell Valley | 0.3 |
Ryan Keiffer and Lucia Varela, UCCE, are conducting the 2018 leafhopper monitoring. For more information, please visit the Areawide Virginia Creeper Leafhopper website: http://ucanr.edu/sites/vclh/