Driving around Glenn County in early March and looking at walnut orchards, about all you’d see was freshly pruned trees and clean berms as most growers finished winter field work.
“For the most part, things are quiet in the orchards right now,” says University of California Farm Advisor Bill Krueger, based at Orland, Calif. In a few cases, though, some growers hadn’t yet pruned their younger trees.
“Research a few years ago showed that pruning younger walnut trees later in winter, or when they are just beginning to grow, encourages more bud break,” he explains.
Over the last weekend of February, almond growers were running their irrigation systems, mostly solid set or microsprinklers, to protect trees from sub-freezing temperatures.
However, Krueger says he doubts the cold weather posed much of threat to walnut trees, even the earlier varieties. In this part of the Sacramento Valley, they typically don’t begin to break buds until mid-March or later. Based on chilling hours, the bloom this year should be fairly uniform, and that would mean a better nut set.
“We had some good chilling early on,” Krueger says. “Temperatures warmed up some in January. but then turned cool again, so I don’t think chilling will be much of a concern for growers this winter.”
Glenn County farmers have also seen a variation in precipitation patterns this past winter — good rains early on were followed by quite a long dry spell before the recent wet weather returned. That’s why Krueger suggests walnut growers check soil moisture levels now.
“If you have tight soils and don’t get good water infiltration, you may not yet have a full soil profile going into spring.”
By the middle of this month, he expects growers to have begun setting codling moth traps in anticipation of the three or more flights of the insect that typically occur each season. Usually, the first flight begins toward the end of March.
As in other areas of the Sacramento Valley, planting of new walnut orchards has been on the upswing in Glenn County the last two or three years, Krueger notes. Part of that is because walnut trees are less susceptible to wind damage than almond trees. Strong prices for walnuts have also helped spur interest in starting new orchards.
“For a long time, until recently, row crop farmers were going into almonds more than walnuts,” he says. “But, that’s been changing in favor of walnuts. Also, more and more almond farmers are beginning to get into walnuts to diversify their business, while being able to use much of the same machinery.”