Dave Keyawa believes his Sacramento Valley walnut crop is shaping up to be a large one. He and his brother, Ronald, operate Keyawa Orchards, Inc. in Butte and Glenn counties.

“If everything goes right, it should be a good year,” he says. “There shouldn’t be any surprises as far as the ability of the industry to move the expected large crop — it can use every one of the walnuts. Demand is great.”

He expects his Chandler and Howard varieties to bear heavy crops; in fact, during the week of June 21 he was tunneling both varieties to remove limbs that had dropped too low for tractor operations due to the weight of the nut load. Plenty of chilling hours along with a mild, wet spring have contributed to favorable production prospects.

“Rains during bloom helped the crop by removing some of the pollen,” Keyawa explains. “Too much pollen without enough rain can cause pistillate flower abscission (PFA). But since we had rain at the proper times, we’re seeing a decent set on all our varieties — Ashley, Chandler, Hartley, Howard, Serr, Tehama and Vina.

However, the rain also brought with it the prospects of walnut blight, necessitating an aggressive fungicide program.

“We like the rain but, at the same time, we have to keep up with a bactericide to protect our trees. Any moisture, even morning dew, can cause the blight bacteria to grow and be dispersed in the tree canopy tree. We continue to spray for blight unless we expect a long dry period.”

Keyawa begins the blight sprays once buds have reached the prayer stage and start to unfold, applying a bactericide weekly to every other row, depending on the variety and stage of tree and nut growth. Usually, he continues this schedule, rain or shine, through May, until he’s convinced there’s almost no chance for any more rain.

The timing of the sprays is based on crop development rather than calendar. This year, for example, he estimates his crop is about two weeks later than normal. “The calendar may have said May, but for the trees the weather was more like the last week of April, when conditions were more favorable for blight,” Keyawa says.

In a wet year like this one, he may treat Ashley, one of his earliest varieties, as many as eight times and Chandlers up to six times in a season. He normally sprays any one variety about four times a year. If wet ground prevents the timely use of a ground rig, he uses a helicopter to apply the bactericide.

This was the first year to use Manzate, under a Section 18 emergency exemption, to control blight. It replaced Manex, which is no longer permitted. Some walnut trees growing near houses where he chose not to spray Manzate allowed him to assess its effectiveness. There is moderate blight in the untreated trees.

“I’m very pleased with the results,” Keyawa says. “The bactericide is working for us in the treated areas.

This is also the first season he has used pheromone-emitting puffers to disrupt codling moth mating. After extensive research, he and Ron chose to implement this technology on about 850 acres. The idea is to reduce the need for pesticides to control the moths over time.

“This seems to be the wave of the future for coddling moth control,” Keyawa says. “The pheromone should mean fewer and fewer moths each generation. We’ll continue with our normal coddling moth spray program this year.

“The pheromone will disrupt the mating of three generations of moths each year. So, if everything goes right, we should have a very low number of coddling moths in by 2013 and, hopefully, no need for spray control.”