Despite challenges, optimism rules
Tiny grape bunches – reason enough for optimism. Photo by Jay Gamel.
May in the vineyard is the time when optimism rules. We can now see the tiny grape bunchlets – each about one to two inches long. The individual grapes are spheres a mere 1mm in diameter. By month end each will open up with a tiny blossom, ready for pollination, and on its way to becoming a delicious grape. Each growing cane left after pruning should have two grape bunchlets that will become bunches. I call May the month when optimism rules because you can now go into the vineyard and actually see if each cane is indeed working on its assigned two-bunch quota for the September harvest. In some years, some canes may only have one would-be bunch or, now and then, no bunch at all. However, all seems well with vintage 2014. As we approach the end of April all growing canes appear to have gotten the memo about their two bunch assignment. Growers are so seduced with even a glimpse of optimism, I can almost start to write bank deposit slips!
May in the vineyard is the period of grand growth when each cane may actually grow two inches a day. Vintage 2014 will be my 33rd harvest at MacLeod Family Vineyard, but somehow each year I manage to forget the difficult obstacle course the vines and I still have to run together before reaching a successful harvest. Go back to bed, George! This kind of critical thinking is too scary!
The question of water remains
Speaking of scary, facing up to the issue of water usage in the vineyard is like throwing a bucket of cold water on May’s optimism. The recent feature story in the Kenwood Press presented between the lines a host of difficult decisions in our future. What crops can we use water for? How do we regulate the amount of water we can pump from subsurface sources? How deep can we drill more wells to further deplete subsurface water supplies? Historically, all the hillside vineyards in Sonoma Valley were dry-farmed, until the development of black plastic drip lines made it possible to irrigate on hillsides. Four years ago we started an experiment, planting 50 zinfandel vines to practice learning to dry farm, i.e., no irrigation, only natural rain water. All 50 vines have survived, and this month we will be grafting them with zinfandel bud wood. Sounds promising, but dry-farmed vines take about twice as long to come into commercial production and generally produce less fruit, so whether the practice is financially feasible remains to be seen.
A significant victory in the war with insects
Plant scientists have recently been able to develop synthetic female sex pheromones for many insects that enable the grower to use sexual mating disruption to control many pests. May sound kinky, but it’s really just putting good science to work. If you place small amounts of the targeted female insect’s pheromones in your vineyard, the males of the species are attracted to it but find no female insects. Hence there is no mating, no reproduction, and no new insects.
Here in Sonoma Valley we have just fended off an invasion of the European Grapevine moth using exactly this technique. This moth lays her eggs in the center of the tiny grape bunches. They subsequently hatch and the young larvae befoul and destroy the center of the grape bunch. County Agricultural personnel placed small red boxes in suspected areas throughout vineyards in Sonoma and Napa counties. The inside of these red boxes were plastered with glue-like stickum along with a tiny capsule of the sexual pheromones of the female European Grapevine Moth.
Now let your imagination take over. It is nighttime and the male moths are flying around in the vineyard. Suddenly one of them catches a whiff of that female sex pheromone, gets excited and flies down, discovers the red box source, flies in the opening and gets stuck on the stickum. A few days later a young county engineer comes out, opens the red vineyard boxes and counts the number of males caught. In this way we learn just exactly where, and in what numbers, the European Grapevine Moth is present. This in turn allows growers to deploy a targeted spraying program and significantly reduce the timing and areas of pesticide spraying. This targeted spraying has in effect eliminated the moth from Sonoma County and greatly reduced affected areas in Napa County. Good news for all. Except the male moths. Sorry, guys.
Owner, Indian Springs Ranch and Vineyards