The other day I was reading “Lack of Sex Among Grapes Tangles a Family Vine” in the New York Times and came across the line “…a host of pests have caught up with the grape, obliging growers to protect their vines with a deluge of insecticides, fungicides and other powerful chemicals.”

The line was a throwaway, with no supporting evidence. But this is received wisdom, right? Doesn’t everyone know that modern commercial agriculture can’t exist unless growers use an ocean of dangerous environmental toxins?

Well, not at our vineyard. As I have said before, we farm in a manner that “…I would have no fears of my kids running around on site, getting dirty and putting things in their mouths.” Most of the growers I know in this business do as well. So why is the idea that we are drowning our grapes in pesticides so pervasive? Where is the evidence?

Data Sources

I spent time last night (in one of my frequent bouts of insomnia) looking for the evidence. First I decided to simplify things and focus just on data for Sonoma County. Sonoma has vineyard operations large and small, industrial and artisanal, high-dollar and low-rent, hidebound and cutting edge. I make the explicit assumption that pesticide use trends in Sonoma are fairly representative of trends in the wider industry.

Second, I went to primary data sources. For Sonoma wine grape acreage I went to the “California Grape Acreage Report: 2009 Crop” published by the NASS. For the amounts of pesticides used in Sonoma I went to the site for the California Department of Pesticide Regulation to find the annual Pesticide Use Report. I pulled data from the Sonoma County Summary Report for wine grapes, for each vintage from 2001 through 2009.

In the CDPR reports, every material — or any aggregate of materials — is listed in a single line with the total pounds of active ingredient (AI) applied in the year, the total number of applications of that AI and the sum total of acres treated. If an acre is treated more than once with the same material it is summed into the total more than once. In 2009 while there were actually 57,150 acres of wine grapes in Sonoma, a total of 1,995,710 pounds of registered materials were applied to a total of 726,475 treated acres in 40,653 separately listed “applications.”

I guess this means that each acre of wine grapes in Sonoma received an average of 2.75 pounds per acre of registered materials in the year, or on average 49.09 pounds of registered material per application. I’m not trained as a Pest Control Adviser but it seems to me that neither number is “correct” nor conveys much useful information. More interesting numbers can be arrived at by simply dividing the total material applied by the actual number of wine grape acres to give 34.92 lb/ac, or by dividing the number of treated acres by the actual acres which gives 12.7 treatments per acre — which is around the number of applications of sulfur one might expect to apply to a vineyard in the course of a season to prevent powdery mildew.

Which leads to the next caveat in the CDPR data: not all registered and reported materials are pesticides (or fungicides, nematicides, herbicides, or -cides of any sort) — not all are even considered be “toxic.” In 2009 the top 5 registered AIs by total number of wine grape acres treated in Sonoma were: sulfur (by a wide margin) followed by three components of adjuvant sticker/spreaders used in applying sprays of other AIs (these adjuvants are on EPA List 4 “Inert Ingredients”), and glyphosate (the active ingredient in Roundup™). With the exception of glyphosate, the others are approved for organic viticulture. It is important to recognize that the materials required to be reported to CDPR are not all equally vile.

I refuse to accept that controlling powdery mildew with sulfur and surfactants that are registered for organic viticulture — and are widely considered to have low toxicity, don’t cause cancer, reproductive or developmental problems, or endocrine disruption, and have little or no environmental persistence — amounts to “…a deluge of insecticides, fungicides and other powerful chemicals.” So I turned to the Pesticide Action Network to help me determine which “powerful chemicals” are of real concern. PAN maintains a comprehensive pesticide database, and has worked with Californians for Pesticide Reform to identify a set of “most toxic” pesticides — their “Bad Actors.”

Toxic Materials — The Bad Actors

PAN’s “Bad Actors” are known or suspected acute toxins, carcinogens, cholinesterase inhibitors, ground water contaminants, reproductive or developmental toxins, and/or endocrine disruptors (I can find no pesticide that fits ALL of these categories). I pulled a list of “Bad Actors” from PAN’s list of the top 50 pesticides used on California wine grapes in 2008, and then tracked the cumulative use of twelve listed compounds in Sonoma from 2001 through 2009.

I did some research on each of the “Bad Actor” AIs I followed, and was unable to find unqualified independent support for the inclusion of all compounds on the list. Of them all, I decided to omit data on “mineral oils,” because the only place I could find them characterized as carcinogenic was on the PAN list. Mineral oils are approved for organic viticulture, considered inert by the EPA and even listed as GRAS by the FDA. The sole reason I can fathom for their “Bad Actor” listing as a carcinogen is that they are derived from petroleum distillates, and petroleum distillates require a Prop 65 warning. I discovered a PAN update referring to mineral oils that states: “The inclusion of these compounds is misleading, since only a small fraction of the components of these oils are carcinogenic…” compared to other AIs where 100% of the material is toxic or carcinogenic.

The Result

I added up the pounds used of the eleven “Bad Actors” and divided by the actual vine acres in Sonoma for each year studied to see if we actually are drowning our vines in toxic chemicals — contrary to my experience and expectation. Enough beating around the bush; here’s the money shot:

Sonoma Pesticide Use 2001 - 2009

Of the 34.92 pound average application of AIs per real acre in Sonoma in 2009, just 1.53 pounds, or 4%, were “Bad Actors.” And though the number of wine grape acres in Sonoma increased by 21% from 2001 to 2009, the rate of use of the “Bad Actors” has decreased by two-thirds over the same period. The trendline suggests that at the current rate of decrease, the use of the “Bad Actors” on the list at this time will effectively reach zero in 2014.

A pound and a half per acre (and decreasing) does not strike me as a deluge, but the situation is even better than this graph suggests. The worst actor on the PAN list is 1,3-dichloropropene, which some growers use as a pre-planting soil fumigant. Although it never gets on or into the grapes themselves, the material is universally recognized as a carcinogen with high acute toxicity and the potential for groundwater contamination. In 2009, 1,3-dichloropropene represented a whopping 70,049 pounds of the 87,408 pounds of “Bad Actors” reported County-wide, and was applied to just 211 of the total 726,475 treated acres in Sonoma. Backing 1,3-dichloropropene out of the data leaves 17,359 pounds of toxic chemicals applied to Sonoma vineyards, or just 0.30 pounds per acre.

Conclusion — No Pesticide Flood

I humbly submit that the idea that wine grapes are being drowned in powerful chemicals is factually incorrect and absurdly hyperbolic. As the Gray Lady puts itself forth as the anchor medium in “the reality-based community” we should expect the reporters and editors at the New York Times to engage more in fact and less in sensationalism.

The question of how vineyard pesticide use is portrayed is a small part of my concerns over the the Times article. In a future post I may deconstruct the central thesis and rebuild it as it should have been done from the first.

If anyone is interested in the abstracted data and calculations, click here to open the spreadsheet.