A month of below normal temperatures has slowed the growth of Mitch Sangha’s 400 acres of Thompson seedless grapes near Del Rey, Calif.
After budding out the last week of March, the vines had produced about 6 to 10 inches of new growth at mid-April, when nighttime temperatures were still in the 40s. “The vines are about a week or two behind normal,” says the third generation raisin grower.
Continued wet weather had increased the threat of his two main disease concerns — powdery mildew and phomopsis. To protect the vines he’s been spraying fungicides about every two weeks since bud break. Starting with liquid sulfur switch, he’ll switch to other products, alternating chemistries to avoid fungicide resistance. “Because of the disease pressure, we’ll be making some extra sprays this year,” Sangha says.
In between sprays, he’ll be dusting vines with sulfur and will continue treating for powdery mildew until berry softening. Normally, that occurs around the end of the June. However, this year that may be pushed back into July unless warm weather speeds up development of the crop.
In the first week of April Sangha also sprayed copper and zinc fertilizers on the vines. Like other growers this year, he is taking a hit from the political unrest in the Middle East, which has pushed up the price of oil and products made from it, including fertilizers.
“Every time I call our supplier I get a new price on nitrogen and that price is guaranteed for only a few days,” he says. “Compared to last year, our nitrogen costs have doubled, and potash has almost doubled. Even dusting sulfur costs twice what it did last year.”
However, he hasn’t been stung by the recent spike in diesel prices. Prompted by news from the Middle East he paid for this season’s fuel deliveries in February.
“I bought a lot of diesel then as a hedge against any price rise. I hope it’s enough to get us through this year. Two years ago, when fuel prices went up, I got caught at the other end and paid the high prices. That’s the kind of situation where you get experience. But, you have to live through the misery to get it.”
Sangha has also been gaining experience in dealing with the European Grapevine Moth (EGVM) threat to California’s grape industry. Although none have been found in his vineyards, he is one of 626 farmers growing grapes in Fresno County’s only European Grapevine Moth quarantine zone. It covers 92 square miles southeast of Fresno,
The federal quarantine zone was established last year after 11 male moths were caught in the area. Pheromone traps are being used to determine the extent of any EGVM infestation. Last year, about 7,500 traps were placed throughout the county. This year, following USDA recommendations, the county increased that number to 11,000.
The quarantine has meant extra paperwork for Sangha and the other growers in the zone to document compliance with the various quarantine requirements. Also, they’ve been taking action to help prevent the pest from becoming established. Treatment options include traditional and organic ovicides and larvicides.
He expects to make his first insecticide application at the end of April to coincide with the season’s first flight and will re-treat about every three weeks until the area is declared free of the pest.
To date, no moths have been caught in this zone since one was trapped last June 21, during the flight of the moth’s second generation. If none are trapped this year, the county can petition the USDA to end the quarantine.
Tye Hafner, Fresno County’s deputy agricultural commissioner, is encouraged by the results. “We’re very hopeful that the treatments last year were successful in eradicating the moth,” he says. “This year we have to prove it.”