It may be an official off-year for California’s alternate-bearing pistachios trees, but the healthy looking trees now give Brian Blackwell reason to expect a good crop from his orchards.
Most of the orchards are in Kern County, but Blackwell Farming Company, based in Bakersfield, Calif., also grows pistachios in Kings, Madera and Tulare Counties.
Overall, production in California this year is expected to decline from last year’s record level. Still Blackwell expects this to be a very good off-year for growers.”
“We had good chilling, a very pleasant spring, and all the heavy rains earlier have contributed to a good crop,” he says.
Many of his younger trees, six through eight years old, sported an early, prolific bloom this spring, but over time many of the berries started to shatter. He suspects the cause was a set too large of for the trees to sustain.
“I haven’t seen shatter as significant as I saw this year,” he says. “But, I have never seen such a significant bloom on younger trees as I saw this year either.”
“I load up the trees now with phosphorus and potassium to prepare them for nut fill, which should start the middle of this month.”
Diseases haven’t been a problem so far. “Because of the late spring rains, we could very easily see alternaria and botryosphaeria later,” he says.
Early August to mid-September is the critical period for development of alternaria late blight, which can cause fruit staining, early defoliation and lead to moldy nuts. Usually, the disease is more a problem for growers in Kern County, while botryoshphaeria, considered the most serious disease of California pistachio trees, poses a greater threat to growers in Tulare County and northward. It destroys shoots, leaves and nut clusters
Blackwell has dealt with three serious infections of botryosphaeria over the past 16 years on one ranch in Tulare County.
“We had to make three separate fungicide applications in June and July and then, in late August we had to take out all the diseased fruit and shoots,” he says. “Controlling each outbreak cost about $300 to $400 an acre.”
To ward off botryosphaeria, he treated his trees with a fungicide during the first week of June and again, with a different chemical, at the end of the month. The first spray also included an insecticide to control stink bugs.
Good orchard sanitation and timely insecticide treatments have kept navel orangeworm populations very low, he says.
All of Blackwell’s orchards are drip irrigated. He’s frustrated that, despite the end of California’s drought, he’s still not getting his full allocation of water from the State Water Project. Some of that water is being diverted to protect Delta smelt and Chinook salmon.
“Even though the mountain snowpack was over 100 percent this year and the reservoirs are full, we’re only getting 85 percent of our state allocation of water, because of the water being turned out to the ocean,” he says.
Despite the cutbacks over the past few years, Blackwell has been able to meet his trees’ need for water, either by buying more surface water or using water from deep wells. The weather this past winter and spring helped fill the soil profile in orchards.
“We were able to reduce the amount of water we put on in April,” he says. “That saved some water on the front end of this season to help get us through the back end with enough water for our trees this year.”