With good soil moisture levels following late winter and early spring rains, all that Don Norene’s walnut trees needed to prod them into serious production mode was warm, dry weather.
“We didn’t have that in April,” says the veteran Sutter County grower, who has also serves as chair of both the Walnut Bargaining Association and the California Walnut Commission
“Once May rolled around and temperatures ramped up, things have improved greatly. The trees have good vigor. In the second week of the month, we had a lot of nice days in the 90s, and by the middle of May the forecast was for more decent weather. However, if we get the cool weather forecast for the week of May 21 and the rain predicted for the 25th, there would be some concern about walnut blight.”
Norene Ranches, Inc., grows Ashley, Chandler, Chico, Hartley, Howard and Vina varieties on 700 acres near Rio Oso, Calif.
Bloom started in early varieties, like Ashley and Chico, in late March; Chandler, his latest variety, began blooming the third week of April. A month later, nutlets on Chandlers and Hartleys measured from one eighth to one quarter inch in diameter. Depending on varieties, some nutlets on other trees were about twice as large.
It’s much too early to make a realistic forecast of this year’s crop size, Norene says. “But, based on trees in this area I don’t see the prospect of a record crop. Of course, that doesn’t mean it couldn’t happen.”
Some rain at the end of April and a sprinkle a few days later added to concerns about walnut blight. Early-leafing varieties are most susceptible to walnut blight, which tends to be more severe in northern California. But Norene is hopeful that he and other growers in the area can avoid a repeat of the heavy disease pressures they experienced last year, when rain fell through the month of May and beyond. In fact, one storm last season brought 1.5 inches of rain to his orchards June 29.
Although a few neighbors report some blight in their orchards, including high levels in one block of Vinas, Norene hasn’t seen any in his trees so far.
He began his blight control program, which usually includes three or four sprays, the last week of March with the start of bloom in early varieties. The sprays protect buds, flowers, and developing nuts from disease-causing bacteria that are spread by rain. Depending on weather and blight pressures, he normally treats trees once a week while the disease remains a threat. By mid-May, he had just about finished these applications.
“I’d like to wrap them up, but I’m not sure I can,” he said at the time. “I might treat every other row to make sure we have some protection in case some rain comes along.”
This is the fourth season Norene has controlled codling moth using pheromone-emitting puffers to disrupt mating. He evaluated the effectiveness of mating disruption by monitoring moth trap counts.
“On average, one trap catches about four of them a week. That’s much less than we typically caught when we were spraying for the pest. Mating disruption has been very effective in the Rio Oso area, and I’m quite happy with the results.
“In a wet, cold spring like this one, we’re always concerned about the impact of the weather on root systems and crowns of our rootstock. I continue to look for rootstock that can accommodate the kind of weather we have in northern California,” Norene says.