Stuart Schroeder of Stone Horse Farm drives a plow horse to cultivate a vineyard row at Frog's Leap, which is dry farmed.

Rutherford, Calif. -- The fourth Organic Winegrowing Conference sponsored by the Napa Valley Grapegrowers was held at Frog's Leap Winery on Wednesday and Thursday. As in the past, it sold out as growers and winemakers gathered to hear the latest news and learn more about organic grapegrowing.

After last year's emphasis on marketing issues, this year's conference refocused on technical issues. Talks about pest management were among the more riveting, as experts shared their knowledge at a panel examining today's biggest concerns -- notably mites, mealybugs and leafhoppers -- and included a discussion of biopesticides. Other speakers concentrated mostly on biological controls.

Vine mealybug management
After a series of valuable but serious sessions, Monica Cooper, who has been farm advisor in Napa County for only three months, presented an entertaining summary of ways to manage the vine mealybug, one of the most serious recent pests in Napa County.

She mentioned that four types of mealybugs exist in Northern California: The grape version has long been present but mostly under control, while the relatively new vine mealybug is the biggest problem.

Mealybugs can be controlled with mating disruption, biological control using predators and parasites, managing ants that protect them, and with insecticides. Resistant rootstocks have promise, too.

For mating disruption, artificial pheromones are released that confuse the males, preventing them from finding and fertilizing the females. A mated female can lay 150 to 700 eggs. In contrast, if she isn't fertilized, she will lay only about 10 nonviable eggs. The process also disturbs the sex ratio to produce more males. One deployment of Checkmate pheromone dispensers is required per year, typically around May. About 250 dispensers have been recommended per acre, but trials are going on to see if lower levels are effective. This process works best with low densities of mealybugs.

Biological control depends on a number of predators and parasitoids including Mealybug destroyers, Lacewing, Anagyrus pseudococci wasps, Coccidoxenoides perminutus, Leptomastidea abnormis, Scymnus and Cryptolaemus parasitoids. Some deposit an egg in the female mealybug, where it grows, turning the pest into a "mummy" and eventually exiting though a hole it creates. The recommended release rate is 3,000 to 5,000 per acre per season.

Cooper mentioned that controlling ants is important, too, because the ants collect the mealybugs' "honeydew" secretions and will attack predators to protect them. Ants can be controlled with baits of sugar water and diluted insecticide, which they will take back to their nests.

Organic insecticides are available including JMS Stylet oil and Oroboost. Broad-spectrum products also are available, but they aren't organic.

One interesting possibility is mealybug-resistant rootstocks. It appears that rootstocks with nematode resistance also may resist mealybugs. In this case, the rootstock is allowed to form an extended trunk. Cooper said the bugs are easier to control in the leaves than when they burrow under the bark of the plant.

She said that conventional insecticides (Lorsban, Applaud and Venom) can kill 96% to 99% of the bugs, while mating disruption and biological controls alone kill 84% after three years of application, while adding the Applaud growth inhibitor cuts percentages 98%. It takes three years to see measureable change, she said.

Predatory and parasitic insects and arachnids

 

Kim Gallagher of Sterling Insectary spoke about the predatory critters she raises to fight vineyard pests; Napa farm advisor Monica Cooper explained methods to control mealybugs organically.

Kim Gallagher of Sterling Insectary, who raises and sells predatory insects and other creatures, discussed using predatory mites, which are eight-legged acarinas of the arachnida class (like spiders), not six-legged insects. She said, "Mites and vine mealybugs are weird. They don't act like other insects."

While spider mites damage plant leaves, predatory mites eat spider mites. They should be released at the first sign of spider mite infestation. They are shipped overnight on cut bean plants and can be sprinkled or blown on to vines. "They're like hyenas running around feeding on pests," Gallagher said.

Her company also sells Anagyrus pseudoccoci parasitic wasps, which lay their eggs in vine mealybugs, and Cryptolaemus montrouzieri mealybug destroyers, which infiltrate mealybug colonies and feed on them.

Glenn McGourty, the Mendocino/Lake counties farm advisor, also reported on trials of predatory mites in Lake County, where they have demonstrated value in reducing spider mite population.

Developments in biopesticides for grapegrowing
Among organic grapegrowers, biopesticides -- certain types of natural products (microbials and biochemicals) used to control pests, plant diseases and weeds -- are a bit controversial. Some growers feel that substituting "natural" pesticides for synthetic formulations goes again the grain of organic farming, and that growers should depend instead on integrated systems to fight pests.

Nevertheless, many growers are comfortable with the substitution and find that the naturally derived substances are a viable solution for even some severe pest problems. They like these products because they can provide increased yields and quality, as well as handle emergencies and weather events.

They represent low risk to non-targets and environment. Workers can spray in the morning and be back in field in the afternoon, and they can be applied right up to harvest. Biopesticides act through complex modes, and they prevent or reduce development of resistance.
 
Pam Marrone of Marrone Bio Innovations has been involved in developing and marketing many natural pesticides. She reported that they are a growing trend, as it becomes more and more expensive to develop chemical pesticides. "It now takes an average of 10 years and costs $200 million to develop new synthetic chemicals and bring them to market," she said, adding that the cost for natural versions is much lower, three years and $5 million.

According to BBC Research, biopesticides are growing rapidly and should reach $1 billion next year, compared to $30 billion for synthetics. Among the success stories in biopesticides are Bacillus thuringiensis (Valent Biological DiPel/Xentari and Foray) and Myrothecium verrucaria (Valent Biological DiTera), Bacilluspumilus (AgraQuest Serenade), B. subtilis 713 (AgraQuest Sonata), distributor Monterey AgResources Kaligreen (Potassium bicarbonate) and JMS Stylet oil.
 
Interestingly, not all natural products are biopesticides. Compounds such as pyrethrins, spinosad and abamectin are "natural," but classified as chemicals by the Environmental Protection Agency if they act on the nervous system of the pest. Other examples include Azoxystrobin fungicide (Syngenta), derived from a mushroom, Tebufenozide insecticide
(Rohm & Haas), which mimics insect hormones, and Spinosyn insecticide (Dow) from a microorganism.

Biopesticides classified by the EPA Biopesticides and Pollution Prevention Division include genetically modified crops with plant-incorporated protectants, microbials (e.g., bacteria, virus, etc.) and biochemical products such as plant extracts, pheromones and fatty acids that act in what is ironically called "nontoxic mode of action to the pest," such as suffocation, desiccation, anti-feedant and mating disruption.

These substances must pass many tiers of non-toxicity, including rat acute oral, inhalation, iv, dermal; rabbit eye; guinea pig skin sensitization, product chemistry, batch analysis, microbiology/qc: no human pathogens, ecological effects (non-target birds, fish, daphnia, honeybees, lacewings, ladybeetles and endangered species) review. In addition, California requires that they work, the only state to do so.

After EPA approval for the National Organic Program (NOP) listing, these products must also be approved by the Organic Materials Review Institute, which can take three to six months.

Unfortunately for the producers, Marrone admitted that some issues are holding back wider acceptance of biopesticides. These include a perception that they're not as effective as synthetic chemicals or even that they're "snake oils." The market is also highly competitive, and many prospective customers see no strong reason to change.

Many users lack knowledge and understanding of biopesticides, too, and distribution channels are complex, while the small companies involved do not have funds for all the required field and demonstration trials and customer education.

Marrone's company attempts to counter these problems partly by developing biopesticides that lower the cost and increase yields in organic farming and improve yield and quality in conventional farming compared to chemical-only systems. She formed Marrone Bio Innovations in 2006, and so far the company has launched GreenMatch bioherbicide containing citrus oil, other oils and organic surfactants, and Regalia biofungicide for powdery mildew and botrytis (formerly KHH Biosciences Milsana). Its Zequanox to kill invasive mussels is at the EPA for approval, and four more products are in development, with 20 early stage candidates.

Marrone develops products by collecting samples from around the world and testing them. The products are scaled up through fermentation processes.

Registered biopesticides from other companies include:
•    NemaQ -- Quillaja saponaria, extract from Chilean tree from Monterey AgResources
•    Actinovate Biofungicide (suppression of mildew/Botrytis) from Streptomyces lydicus -- Natural Industries
•    Requiem Plant extracted insecticide (leafhoppers, mites in grapes) from AgraQuest

Awaiting approval is Bacillus firmus nematicide from Agrogreen (Israel), which was purchased by Bayer.

In the works at Marrone are a new microbial insecticides and a bionematicide. Get more information at marronebioinnovations.com.

Other speakers covered topics including compost and hummus, cover crops, certification, labels and mildew control

The conference included suppliers of products for organic farming, and there were demonstrations of specialized equipment for organic growing, use of horse and plow to till, Olde English Southdown Miniature Babydoll sheep, beneficial birds and bees, and a discussion of dry farming as