Anyone living, or visiting, the Napa valley has seen the European Grapevine moth signs.
This pest invaded California almost a decade ago and attacks the blooms of the grape flowers. Why is this problematic? Because, no blooms, no grapes, no grapes, no wine.
The European Grapevine moth decimated vineyards in Temecula, and was headed North. Since the moth only has a flight path of 30 yards, it was clearly hitching rides. Billboards, bumper stickers and signs urge individuals not to bring plants or produce into agricultural counties in California.
But it clearly isn’t feasible to quarantine an entire county, so other precautions need to take place.
Say what you will about how pristine European vineyards are, and how US agricultural standards are lackadaisical, but most people I know who are blessed enough to own land in the Napa Valley take care of it. This means minimal (or no) use of chemicals, and an attempt at nutrient balance in the soil. So, the answer to getting rid of moths is definitely not to spray the vineyard. Not only do you want to limit chemicals on the grapes, wine, or runoff water, but you don’t want to kill other organisms that are of benefit to the soil or harm plants that break down nutrients for the vines.
“Integrated pest management” is a field of study where one looks at the lifestyle of the pest in question and tries to naturally disrupt it. This may be introducing natural enemies, or reducing surrounding shrubs as breeding ground. In the moth’s case, it involves mating disruption.
If you are a lonely male grapevine moth looking for love, you do what all men do- you go searching at the local hangout, flirt with girls, and gauge who might be into you. In the grapevine moth’s case, this interest is determined by a pheromone that is released from the females that indicates they are ready to mate (green-light) or that they have already been mated with (red-light).
It was a sad year to be a grapevine moth in Napa. If you walked though vineyards you might notice very small twist ties on some rows of vines. These tiny ties contained the female “red-light” pheromone. Poor male moths found no luck looking for a viable female this year as they traveled through vineyard flooded with overpowering pheromones telling them no females were interested.
Since the grapevine moth has several life cycles throughout the season, we could monitor if the efforts were working, and indeed they did.
The first cycle count was 100,000 moths in 2010, with only 87 found in the first count of 2011. So in one seasons we were basically able to confuse them into extinction – with twist ties.
But, that isn’t all that went well for the 2012 harvest. Stay tuned for Balanced vintage Part III…