European Grapevine Moth in Mendocino County, Part 2

Two weeks ago, I first wrote about the European grapevine moth (EGVM) in a comprehensive story: The European Grapevine Moth, less welcome than your mother-in-law, is here. Since then, I had a chance encounter with one of the big wheels at Brutocao in Hopland who spoke to my concerns for the unique county wide passion for organic and biodynamic grape farming in Mendocino county in the face of the real threat of complete crop loss to the pest.

While there are completely effective insecticides that can be used by organic farmers, Dipel BT and Entrust Spinosad, they rely on ingestion by the caterpillar rather than acting through simple contact, they also have short periods of efficacy. While the organic options cost no more than their more powerful less green alternative insecticides, the organic insecticide cost is 10-12 times greater due to the need for larger and more frequent applications. Realistically, this means that some vineyards will abandon organic or biodynamic practices and certification; especially in a down economy when expenses cut closer to the bone.

In a conversation today, Mendocino County Agriculture Commissioner Tony Linegar confirmed the higher costs associated with treating the EGVM risk organically, and acknowledged that it hits Mendocino county especially hard because of the county wide dedication to greener agricultural options.

Commissioner Linegar remains optimistic that the infestation can be controlled and the threat to county agriculture fought and won. In addition to the 32 moths found at Dunnewood in north Ukiah, there have been just three single moths trapped; one in an Oak Knoll residence back yard, one in downtown Ukiah near Maple Restaurant, and one in a vineyard directly across from Weibel Vineyards three miles east of Hopland.

The EGVM is not a distance flier, it is suspected that the most found downtown Ukiah may have hitched a ride on a produce truck delivering to Maple Restaurant, and the moth found in Hopland came from trucks that had visited neighboring infested counties then parked for hours in the vineyard where the moth was trapped. It is known that Dunnewood had received fruit from Napa county.

Commissioner Linegar sees an end to the practice of transporting pomace from vineyard to vineyard. Pomace is used by some grape growers as part of a natural fertilizer. Linegar’s commission also will be enforcing tighter regulations regarding composting pomace, ensuring a minimum number of turns and a sustained temperature of 130° F. over 15 days.

Additionally, trucks moving from vineyard to vineyard will need to be cleaned completely, typically by power washing to remove all plant material. Meetings are ongoing regarding how this will be carried out in light of the remoteness of some dry farmed vineyards. Linegar said that there will be random inspections and failure to comply will result in fruit that does not make it to crush.

The EGVM has three cycles and we are coming up on the second shortly; Linegar feels that this is a most important time for Mendocino County’s wine industry and will determine much of what will follow in responding to the EGVM. While spraying of insecticide is voluntary, but recommended especially within a kilometer of a positive trap; increased numbers of moths, if found in the second cycle, could trigger mandatory spraying.

Both Napa and Sonoma Counties have established EGVM infestation, Mendocino County’s moth problem is in the early stages. With 70% of our grapes leaving the county, denying fruit from Napa or Sonoma becomes problematic; and much equipment moves by truck between counties, vineyard to vineyard and vineyard to winery, so while Linegar was absolutely upbeat, positive, and hopeful, it is understandable that many in the industry are expressing greater concerns.

 

The European Grapevine Moth, less welcome than your mother-in-law, is here.

This month, Napa County vintners began spraying their vineyards with pesticides in an attempt to fight infestation of European grapevine moths.

The half inch insect lays eggs in April, and the larvae starts feeding at bud break on grape flowers, then later generations on young grapes, and a third generation on mature grapes.

Since September 2009, after destroying a nine acre Napa Valley vineyard’s crop, when the culprit moth was identified, nearly 30,000 moths have been trapped in the county, and plans are being made to quarantine over 300 square miles of Napa County.

Although the moth is not a long distance flier, it does seem able to ride on equipment from vineyard to vineyard, vineyard to winery, and winery to winery. Neighboring Sonoma County is gearing up to institute quarantine protocols to help control moth movement.

Mendocino County, known for environmentally friendly farming practices, sustainable and fish friendly agriculture, organic and biodynamic grape growers and wineries, is facing a quarantine of nearly 6,000 vineyard acres after first one moth was found just south of Ukiah on a back yard grape vine, then more recently another 30 have been found north of Ukiah.

Tony Linegar, Mendocino County Agricultural Commissioner, suspected the moths were transported from Napa when fruit was moved from Napa County to a winery near Dunnewood’s now infested Chardonnay vineyard. Roughly 650 traps are being set in Mendocino County. Linegar believes this may be the second year the moths have been in Mendocino County, and the worst may be yet to come.

Mendocino County wineries use pomace, the residue of pressed grapes, for natural fertilizer. Alarmingly, the European grapevine moth larvae, left inside the grapes, can sometimes survive pressing and end up in pomace. Several Mendocino County wineries regularly import Napa and Sonoma County winery pomace. The problem could very well have been laid right at the feet of the vines already.

Linegar is asking all vineyards within a kilometer of Dunnewood’s infested vineyard to spray with a larvicide.

Purportedly organic insecticides do exist, and are hoped to be effective.

Only 3 of 18 Insecticides for Lobesia botrana (European Grape Vine Moth) on grape are approved for use in organic vineyards. I found no information on approved insecticide use in biodynamic vineyards.

Bruce Phillips, a Napa Valley grape grower, worries about “the long term sustainability of organic and biodynamic practices,” in the face of forced spraying to combat the spread of, or damage from, the moth.

Mendocino County bills itself as “America’s Greenest Wine Region,” and the threat posed by the European grapevine moth is not just to the grape crops but to an entire way of growing grapes.

The County of Napa Agricultual Commissioner’s website states, “Studies of the European grapevine moth internationally show that larvae feed primarily on the flowers and fruit of the grape, and that they can also feed on number of other hosts, including olives, blackberries, cherries, nectarines, persimmons and pomegranates. ”

There is further concern that after grape harvest, moths may spend the winter cacooned in olive trees on vineyard properties.

Jim Allen, the Solano County Agricultural Commissioner, describes the threat posed by the moth as having “a potential for complete crop loss.”

A Final Report of  an International Technical Working Group brought together to fight the European Grape Vine Moth in California’s north coast, dated February 10, 2010, recommends that suppression measures include ovicides, larvicides, mating disruption, and mechanical control measures. Three generations of the pest impact vineyards; the first from bud break to fruit set, the second from pea sized grapes to ripening, and the third from ripening to harvest. Whether there are any beneficial organisms that might prey on, or control, the moth is unknown at this point.

The second and third generations cause the most damage not just by direct feeding on mature grapes but by predisposing the crop to grey mold, fungus, and rot through webbing and leaving of excrement inside the grapes.

Since their discovery in Napa County; in addition to Sonoma and Mendocino Counties, the moth has been found in Merced, Fresno, and Solano Counties.