Which cide are you on? Vineyard pesticide update

Wines & Vines, April, 2003 by Jane Firstenfeld

Since Rachel Carson's seminal work Silent Spring prompted the 1972 U.S. ban on the hyper-effective insecticide DDT, chemical pest control has remained a ticklish subject. Yes, the brown pelican and other species endangered by DDT's long and lethal half-life have made spectacular comebacks. So have malaria and other deadly diseases transferred by the mosquitoes that were DDT's intended target.

In the three decades since that historic ban, more than 50 chemical pesticides have suffered similar fates, banned or restricted for the greater good. Multi-national chemical companies spend billions to keep ahead of the curve, developing new tonics for new threats to agriculture, animals and humans. It's a costly balancing act, with nature as the fulcrum.

Now, as the wine industry becomes ever more focused on the philosophy of sustainable agriculture, and with it, the tenets of Integrated Pest Management (IPM), not to mention organic and biodynamic farming (see stories, pg. 16 and 42), the economic and environmental costs of chemical pesticides are under closer-than-ever scrutiny.

"Kill It"

Sometimes, sustainability requires drastic measures. With glassy-winged sharpshooter (GWSS) and Pierce's disease (PD) a continued threat and the alarming arrival in California of the vine mealybug, in many cases chemical pesticides are the only way to fly. For the past couple of years, imidacloprid, marketed by Bayer CropScience under the names Admire [R] and Gaucho [R], among others, has been the poison of choice to combat GWSS.

There is also evidence that it's effective against vine mealybug. And, in the words of Dr. Kent Daane, UC biologist, speaking at the Central Coast Vineyard Team's annual educational meeting in Jan., 2003, "We don't want you to think about (vine mealybug) right now in terms of sustainable agriculture. Don't think about what we're doing in areas where it's well established. Here we want you to kill it....Eradication and control now will mean far fewer pesticides later."

The current recommended treatment regimen involves dosing affected vineyards with different, powerful insecticides at various stages of the growing cycle.

According to the UC IPM Pest Management Guidelines: Grape Insects and Mites, "If vine mealybug is found in the vineyard, treatment is recommended. Make an application at bloom to control this pest during the current season. A post-harvest application in September will help provide control for the following season.

Timing, dosages and cautions for applying chlorpyrifos (Lorsban), narrow range oil (Superior, Supreme), buprofezen (Applaud), imidacloprid (Admire) and Provado(R), another Bayer product, can be seen at the Web site ipm.ucdavis.edu/PMG/r302301911.html.

Vintners in Temecula, the Southern California AVA hardest hit by GWSS, received federal grants to pay for applications of Admire and other remedies for the past several years. The PD threat is significantly reduced, but at considerable cost. At approximately $60 to $90/acre per treatment, Admire is among the most expensive of insecticides.

Other costs may accrue as well. Imidacloprid has been banned as a sunflower seed treatment in France since 1999, after sunflower growers suspected it was killing bumblebees, essential to the pollination process.

That same year, imidacloprid was approved for use in the potato fields of Prince Edward Island and New Brunswick. Less than two years later, Canadian beekeepers protested its registration for use on the vast canola fields of that nation's prairie provinces. At the behest of the Canadian Parliament, the Canadian Agricultural Department undertook an investigation to determine if the pesticide was responsible for a disastrous loss of honeybees--a 50% to 80% population reduction in imidacloprid-treated areas. Bayer denied its product was the cause of "mad bee disease," and actually helped to fund the study, but final results will not be known for another month or so, according to the office of John Bryden, Member of Parliament, beekeeper and instigator of the study. As with other chemical, systemic pesticides, the question of eventual pest resistance also applies to Admire.

An Organic Option

A promising alternative in the fight against GWSS is surround [TM] Crop protectant, manufactured by New Jersey's Engelhard Corp. Though registered as a pesticide, Surround does not actually kill the sharpshooters. As the name implies, it creates a barrier that keeps the insects from feeding and thereby transmitting Pierce's disease (PD). In a 2001 study, more than 10,000 acre-treatments were applied post-harvest in Kern County, Calif., vineyards, resulting in "huge reductions of visits by adult GWSS to the treated vines, and egg lay was reduced by 99% on vines that had received the repeat-treatment prescription," according to Engelhard.

Concocted of 95% kaolin, a naturally-occurring clay-like substance, Surround is listed by the Organic Materials Review Institute (OMRI) for use in organic production, and is registered by the U.S. EPA with an exemption from the requirement of a tolerance for residues. Sprayed on vines as needed throughout the year, it produces the visually startling effect of plants "flocked" like Christmas trees, eventually fading to "a pastel look," according to John Mosko, Surround marketing manager. At a product cost of $15 to $16 per acre, it must be reapplied after heavy rains to maintain its protective qualities.