At mid-April, Bob Johnson, director of winegrowing for Snows Lake Vineyard, Lower Lake, Calif., was expecting bud break to begin the third week of the month, assuming warmer weather.
That’s unusually late for the Lake County vineyard and comes after the vines were dusted with snow the first week of April. It was very cold last winter; during February, snowfall on some of the blocks totaled 21 inches.
Snows Lake’s 800 acres of Barbera, Cabernet Franc, Cabernet Sauvignon, Merlot, Petite Syrah, Syrah and Zinfandel, are growing on rolling hills at elevations of 1,800 to 2,500 feet. The late start to the growing season could prove helpful.
“Often, with hillside vineyards like ours, the vines on the top of the hillside break earlier than those at the bottom,” Johnson says. “Because the vines are all ready to break bud and start growing, we should have a more uniform bud break and more uniform grape quality at harvest.”
After bud break, they’ll begin their fungicide sprays, starting with JMS Stylet Oil to take care of any overwintering powdery mildew spores and knock down any spider mites remaining from last season.
“The stylet oil is a very soft material and can be used in organic grape production,” he says. “In addition, we water our roadways to keep down the dust that promotes mites. Also, for the past five years we’ve been releasing beneficial mites to help control the spider mites.”
“They‘re working very well,” Johnson says. “We’re seeing them overwinter and we haven’t had to apply a mite spray for the past three years.”
Due to the volcanic soils, the vines require regular fertilizer applications. So, two weeks after applying the stylet oil, Johnson will spray the vineyards with boron, zinc and iron. Also, this year, he’ll experiment for the first time with some molybdenum treatments prior to bloom.
In June, Johnson will begin the first of several treatments during the season to correct his biggest nutrient deficiency, phosphorous. He’ll apply monoammonium phosphate (MAP) through the drip irrigation system, along with magnesium sulfate salts to meet the vines’ need for magnesium and gypsum to add calcium.
Up to now, there’s been no need for nitrogen applications. That will change this season.
“Several years ago, we began to notice the color in the vineyards fading about mid-season,” Johnson says. “In some areas it was worse than others. The problem was diagnosed as a nitrogen deficiency. So, this year we’ll be applying small amounts of calcium nitrate through the drip systems in mid-season.”
The volcanic soils also add to the irrigation challenge. He uses such tools as a neutron probe and pressure chamber to track soil moisture and vine water requirements throughout the season. “We’re trying to micromanage under- performing areas on a block-by-block basis,” Johnson says.