A decent bloom combined with a strong nut set has set the stage for a promising almond crop for Stanislaus County growers. “A few orchards here and there are pretty spotty,” says Roger Duncan, University of California Cooperative Extension farm advisor for the county. “Some growers say the Butte-Padre production is off this year, but I haven’t seen that. There are quite a few Carmels here. Last season, their yields were down. But this year, I’ve seen some orchards were the Carmel trees were loaded with nuts.”
An early bloom and the higher number of degree-days than usual for this time of the year could mean an early hull split and harvest, Duncan notes. Near the mid-point of April the hulls had reached full size and were beginning to fill. He projects that, overall, the county’s almond crop this year would come in as good to very good. That assumes adequate supplies of water.
“Growers relying on district water for irrigation may see some yield reductions due to limited supplies of water this season,” Duncan says. “But, those with access to ground water should end up with some good yields. Industry-wide, though, production will probably drop from last year, due to cutbacks in water deliveries.”
Several inches of rain, following a mostly dry winter, has helped replenish soil moisture reserves in many of the county’s almond orchards, Duncan reports. As of mid-April, no surface water had been released in the canals. He expects deliveries will begin at least three weeks later than usual. “This delay at the beginning of the season is a good thing, because it will really help growers stretch very limited supplies of water,” he says.
Meanwhile, growers are taking other steps to make the most their available irrigation water this season. For example, some growers who normally would have allowed vegetation to grow in row middles are applying herbicides from one edge of the orchard floor to reduce competition between trees and weeds for water, Duncan notes.
Growers are also keeping closer tabs on moisture levels in their fields using such tools as tensiometers, gypsum blocks and neutron probes to measure soil moisture and pressure chambers to monitor the water status of their trees, he adds.
So far, growers have reported few disease problems in their almond orchards this season, Duncan says. However, they are concerned about bacterial spot, a new disease of almonds which poses a serious threat to some early varieties, primarily Fritz and Ne Plus as well as Padre and Price. Nonpareil, Carmel and many other pollinizer varieties seem to be pretty resistant to the bacteria and shouldn’t require treatment for bacterial spot, he adds.
Caused by the Xanthonmonas arboricola bacterium, this disease produces lesions on nuts, causing some nuts to fall prematurely and reducing the market value of those that remain on the tree for harvest.
There are no labeled products for this disease and most fungicides will not provide protection for bacterial diseases. Last year, the disease caused major losses in southern San Joaquin County between Highway 120 and the Stanislaus River in the Manteca/Ripon/Escalon area and in northern Merced County south of Turlock in the Delhi-Ballico area. “It was real eye-opener,” Duncan says. “Up to then, growers weren’t aware of the disease.”
Periods of warm temperatures in the spring with high dews and rain seem to encourage the onset of symptoms. “These conditions have passed for this season,” Duncan says. “So far, so good. We haven’t seen any problems.”
UCCE farm advisors and specialists are now drawing on the experiences of almond growers in Australia who have battled almond leaf spot to develop programs California growers can use to control the disease.
“This is the first year we’ve developed plans for managing almond leaf spot,” Duncan says. “We’re testing various materials and timing and rates of application. Basically, our approach involves one or two dormant sprays of copper and early-season application of other products.”
Meanwhile, now is the time for growers with a history of rust and scab to treat their almond orchards for these threats to their crop. Typically, that’s done with an application of sulfur or maneb about five weeks after petal fall. “Spraying trees now is a preventive approach,” Duncan explains. “Symptoms won’t show up until May. But, by then, it’s too late for treatments to do any good.”
UC IPM guideline call for following the initial treatment 4 to 5 weeks later in late spring and summer with a Quinone outside inhibitor fungicide (FRAC Group number 11) to control leaf infections. Two or three applications may be needed in orchards that have had severe rust problems.
Egg traps counts to monitor populations of peach twig borer and navel orangeworm have been low up to this point throughout the San Joaquin and Sacramento Valleys, Duncan notes. However, warm weather in the second week of April could help boost trap catches, he adds.
This year, UCCE farm advisors are testing a new type of trap for monitoring PPTB and NOW populations that uses a pheromone to attract male moths. Results are used to determine the best time for insecticide applications. Introduced last year, this pheromone trap is designed to be easier to use and provide more consistent results than the conventional egg traps.
“We’re want to see how we can use the results of the pheromone trap catches to develop a model for spraying insecticides to control the pests,” Duncan says.