New Invasive Vineyard Pest Found in California
European grapevine moth (aka European grape berry moth; (Lobesia botrana) was recently found in Napa County, a first known find for California. The insect has the potential to cause great economic harm to California’s diverse grape industries. The moth was trapped in Napa County’s, famous Oakville grape growing region known for high valued wines. Common to Europe and the Mediterranean, European grapevine moth has been intercepted from across the US where international travelers, cargo or mail disembark from planes originating from overseas. Currently, the Napa County Agriculture Commissioner is working with the CDFA and USDA to survey the area where the moth was first located in an attempt to detect additional European grapevine moths.
European grapevine moth identification
European grapevine moth can be confused with American grape berry moth (Endopiza viteana) native to the eastern United States or European grape berry moth (Eupoecilia ambiguella). Wings of the invasive European grapevine moth, L. botrana, have a mosaic shaped pattern with black-brown, cream, and gray-blue ornamentation (Fig. 1). Larvae tend to develop a purple cast after feeding and will often be found inside the berry. Samples should be taken to a trained university or state entomologist for proper identification and documentation. It is important to note that samples should be enclosed in a sealed container, jar, or vial if found prior to moving the insect (all stages) from an infested site.
Damage
Damage can be seen to both grape flowers and developing fruit. Larvae feed on flowers prior to bloom and continue through bloom. As bloom peaks, larvae protect themselves by producing webbing around the damaged flowers and feeding on neighboring flowers and parts. Second and third generation larvae feed on berries hollowing and contaminating them with excrements (Fig. 2). Cultivars that naturally have tight clusters—like Chardonnay, Pinot noir and Zinfandel—will suffer the most damage. Much like infestations from other worm pests, feeding damage will lead to infections by bunch rot fungi. Raisin and table grape cultivars will also experience damage, especially when bloom is prolonged due to weather, making flowers less responsive to applications of gibberellic acid used for bloom thinning. Table grape cultivars with tight clusters have the least tolerance for the moth due to fruit feeding damage and contamination with webbing, excrements and rot. All life stages can be found in vineyards infested with European grapevine moth but larvae from the second and third generations have been found to be the most damaging when fruit is maturing.
Host range
The host range for European grapevine moth is diverse. In addition to Vitis vinifera (cultivated grape), they also feed on other important agricultural crops like apple, cherry, nectarine, persimmon, plum, pomegranate and olive. It has been documented that privet and some grape cultivars are preferred for oviposition. Plants should be inspected for eggs, larvae and pupae. Larvae can be found in flower or fruit clusters along with webbing and in berries or other fruits. Pupae are frequently found inside a silken cocoon in rolled leaves, inside clusters, and under the bark of any of the previously mentioned host. At this time there are no regulations in place regarding the movement of fruit or other plant material from Napa County but growers and industry representatives should be vigilant. Trapping beginning at budbreak, using a tested pheromone is the best approach to monitoring vineyards for activity. Pheromones attract males to traps and allow one to estimate a population of European grapevine moth. With cooler fall temperatures, adult moths will be absent and only the diapausing pupal stage inside a silken cocoon can be found protected by grapevine bark. Growers should consult with their County Agriculture Commissioner or University of California personnel to determine the best approach to monitoring and properly identifying European grapevine moth.
Stephen Vasquez the UC Cooperative Extension viticulture farm advisor in Fresno County. Walt Bentley and Lucia Varela are UC IPM advisors in Fresno and Sonoma Counties, respectively.
Lbotrana-moth
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Grape Days; a Longstanding UC Tradition
University of California (UC) researchers have extended information at Grape Days for 58 years. Here is a brief history, as remembered by Amand (Kas) Kasimatis and L. Peter Christensen, Extension Specialist Emeriti, Dept. of Viticulture and Enology, UC Davis.
Commodity days were quite popular on the Davis campus in the early fifties; the first Grape Day was held there in Aug., 1951. H. B. Richardson, Ext. Specialist, and A.J. Winkler, Chair of the Dept. of Viticulture and Enology, organized the first program. At the time, there was a lot of field research being done in the University vineyard, so most of the Department faculty put on a demonstration. It included lunch on a lawn with shade trees around the Viticulture fieldhouse and had a luncheon speaker. L. Peter Christensen remembers attending one of campus Grape Days in the mid 1950s. “Nick Dokoozlian Sr. drove the van. It was very popular and awe inspiring for a farm boy.” Amand Kasimatis took over in 1956 and chaired the campus programs yearly until the early 1980’s. In January 1976, Kasimatis, in collaboration with California Association of Wine Growers, developed Wine Grape Day. Additional Wine Grape Days were held every February through 1985, on the Davis campus, with the exception of one that was organized by Vince Petrucci (Professor of Viticulture, CSU Fresno), and held in Fresno. No Grape Days have been held on campus since 1985, but the Department presents RAVE (Recent Advances in Viticulture and Enology) in March.
In the 1960s, Kas established several regional Grape Days at off campus facilities. The first of these was the Coast Grape Day, at the Oakville Station, Napa Valley. Grape Day at Oakville continued for some time, eventually under the direction of Jim Wolpert. The first Grape Day at the Kearney Agricultural Center (KAC), also initiated by Kasimatis, was held in 1967, two years after the center was opened. Kasimatis directed Kearney Grape Days until 1973, when Fred Jensen (Extension Specialist Emeritus, UC Davis) assumed those responsibilities. In the mid 1980s, L. Peter Christensen became an Extension Specialist, and then was responsible for the Grape Day at Kearney until Nick Dokoozlian (former Specialist, Dept. of Viticulture and Enology, UC Davis) took over in the early 1990s. Since 2005, Matthew Fidelibus has organized Grape Day at the KAC. We hope you find this year’s program to be interesting and enjoyable, and that you will join us again in 2011.
Erineum mites
Erineum mite populations seem to be exploding this season. In the past two weeks, a half-dozen samples have been dropped off at my office for inspection. Normally, a few samples are brought in from backyard vineyards, which I expect. However, the most recent samples and calls have been from commercial wine grape vineyards with concerns that it is downy mildew. First, let me assure you that it is not downy mildew. The Valley has not experienced an outbreak of downy mildew since the mid-90’s when a few table grape vineyards were identified with the disease after optimal weather; rain and warm temperatures. The recent erineum mite outbreaks in commercial vineyards are easily explained by a reduction in sulfur use for powdery mildew. Winegrape vineyards tend to experience more frequent outbreaks when wineries request a reduction in sulfur dust so it does not interfere with fermentation. Below is a summary of erineum mite life cycle.
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Erineum mite
We're on Facebook!
Recently we joined Facebook, a social networking site on the internet. To find us, click on the following link: San_Joaquin_Valley_Viticulture. Our pages are public, so you may visit them and view all of the content, without subscribing to Facebook.
When you first visit our site you’ll notice several tabs near the top center portion of the page. Currently, the tabs are labeled “Wall”, “Info”, “Photos”, “Boxes”, and “Notes”. Wall is the default page, and here you will find a list of short messages and updates, including weekly powdery mildew reports. The wall is interactive, and Facebook members can comment on our messages, or add their own. Many of these messages are simultaneously sent via Twitter, and you can receive them that way if you prefer (http://twitter.com/grapetweets). The next tab, labeled “info”, only has the address to the
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Money available to off-set the cost of grape stake disposal
Have you recently removed an old vineyard that had treated grape stakes and now have piles sitting on your property and don’t know how to get rid of them? The Natural Resources Conservation Service (NRCS) is offering financial assistance to California grape growers to help properly dispose of chemically-treated wooden stakes. Treated grape stakes are typically treated with preserving chemicals that protect the wood from insect attack and fungal decay. Chemicals added to preserve wood and known to be toxic or carcinogenic include arsenic, chromium, copper, creosote, and pentachlorophenol. Burning treated grape stakes is prohibited by law.
