What is in this article?:
- Dryland Central Coast vineyard challenged with another dry season
- Silver bullet
- This season’s unseasonably warm temperatures early and the lack of rainfall have forced wine grape growers to alter management.
“All things considered, the vines are doing pretty well,” says Levi Glenn, viticulturist for Tablas Creek Vineyard. He manages 110 acres of primarily Rhône variety grapes near Paso Robles, Calif.
One of those “things” is a second-straight year of drought – no small consideration for the organically-certified vineyard, where all but a few blocks are dry-farmed.
The vineyard gets most of its “normal” 25 to 30 inches of annual rainfall during winter and spring. This past winter was the driest on record, Glenn reports. Since last September, he’s recorded a total of just 16 inches of rain.
The few drip-irrigated areas of the vineyard are located on the more water-challenged hilltops. Elsewhere, moisture in the high-clay soils frequently can be found no deeper than about 6 inches, Glenn reports.
His 2013 season started early, prompted by unseasonably warm 80-degree temperatures, allowing crews to finish field work ahead of schedule.
Anticipating another dry year, Glenn’s crews have been doing more cluster-thinning and leaving more canopy to protect varieties prone to sunburn.
The crop load this season is about average to slightly higher, he notes.
It has been warmer-than-usual and if that continues, Glenn expects the grapes to be ripe and ready for picking around Sept. 1. “It could be a quick, non-stop harvest,” he says. “Instead of the usual 10-week harvest, we could be finished in just six or seven weeks.”
Despite a Powdery Mildew Index ranging between 70 and 100 throughout much of June, Glenn hasn’t seen any signs of the disease in his vines. “But other growers have,” he says. “So, it’s around.”
Because of the area’s low humidity levels, often in the teens, powdery mildew usually isn’t a major threat, Glenn says. Only in cool growing seasons, such as 2010, has he had to ward off mildew.
“We’ve been more proactive the last few years in treating the vineyards to prevent any problems with powdery mildew,” he says. “Usually, it’s a concern only in blocks with more north-facing exposure and little air movement.”
His powdery mildew control program includes a dormant spray of lime sulfur followed by early-season sprays of copper and micronized sulfur before transitioning to Stylet oil. Oil also helps control young leafhoppers feeding on the bottoms of leaves.