At the beginning of August, the hulls were still tight around the nuts in Yuba County grower Jack Gilbert’s walnut orchards. But, judging by the pace at which the crop was maturing, he expects to begin harvesting his earliest varieties, Ashley and Serr, in the second week of September. That would be about a week earlier than usual.
Once underway, all signs point to a bountiful harvest. “It looks to be one of our best crops,” he says. This follows the 2013 season when production was down significantly. However, with strong field prices it turned out to be a pretty good year.
Gilbert, who’s been growing walnuts for nearly 40 years, is now farming 1,650 acres of walnuts with his two sons, Henry and Jack, Jr., on four ranches near Wheatland, Calif. The varieties also include Chandler, Chico, Hartley, Tehama and Vina along with a few Franquette trees.
“The trees aren’t overstressed,” Gilbert reports. “We’ve had a number of 100-degree days but not much sunburn and no disease problems. We should end up with high-quality nuts. We’re very fortunate to have had adequate water for irrigation.”
Depending on the particular block, this includes surface water from one of three irrigation districts. One district has reduced their water allotments this year. However, Gilbert draws on ground water to make up any shortages.
Normally, he begins irrigating his orchards around the first of June. This year, due to the dry winter and low soil moisture levels, he started in April.
Trap counts have shown typical walnut husk fly numbers this year. Based on those results, Gilbert treated his trees for the pest in the second week of July. Depending on trap counts, an additional spray may be required for adequate control, he notes. Sometimes, though, certain hot spots of husk fly activity require a third or even a fourth spray.
Over the years, the timing of his husk fly sprays has moved to earlier in the season. “In the past, we sprayed the first week of August and that took care of the problem,” Gilbert says. “Now, we’re seeing husk flies emerging as early as the end of June.”
The use of pheromones over the last five years to disrupt mating of codling moth has just about eliminated the need for insecticides to control this pest. In fact, no sprays were necessary this season, he says.
An outbreak of spider mites, mostly two spotted, near harvest time last year required a miticide treatment in the first week of September to control a significant flare up in certain blocks. Gilbert has included a miticide with his walnut husk fly spray as his normal practice but will monitor the mite population much more closely this season.
Meanwhile, he and other growers in the area continue to keep a close eye on ground water levels. He’s been monitoring the water table for the past two decades, Gilbert notes.
“We’ve been careful not to overdraft,” he says. “In fact, as surface water distribution has expanded around here, the water table has come up. We’re certainly hoping that we don’t have any significant drop in groundwater levels. But, if we don’t get any rain this next season, all bets about that crop are off.”