Bursting Walnuts

Drought and concerns with over-drafting of ground water cloud the season for a number of walnut growers

“Due to low winter chilling, the leaf out was really erratic, especially for the later-leafing varieties. The timing of bud break was all over the place. So, it’s hard to pinpoint when it started and make comparisons to previous years. But, in this area, Chandlers, typically began leafing out in late March to early April.”

By the last week of May it was still too early for Rick Buchner, University of California Cooperative Extension orchard advisor for Tehama County, to assess likely production prospects for this year’s walnut crop.

As he points out, trying to spot the small, green nuts amid the large canopies of many walnut trees is difficult.

“I like to see a lot of doubles and triples on spurs, which would indicate a good crop,” Buchner says. “The few I’ve looked at look just so-so.”

But, he is sure of at least one thing:

“Due to low winter chilling, the leaf out was really erratic, especially for the later-leafing varieties,” he says. “The timing of bud break was all over the place. So, it’s hard to pinpoint when it started and make comparisons to previous years. But, in this area, Chandlers, typically began leafing out in late March to early April.”

Not surprisingly, the fourth straight year of drought and uncertainties about having enough irrigation water to get the crop through the season top the list of concerns for walnut growers up and down California, he reports.

“Those with pretty good ground water supplies are doing reasonably well,” Buchner says. “That includes most growers in Tehama County. But, elsewhere, getting delivery of surface water in some districts is becoming more and more difficult. The quality of our ground water here is still pretty good. But, in other areas of the state, high soil salinity levels and boron toxicity are of increasing concern to walnut growers.”

The Water/Irrigation Program section of the Tehama County Cooperative Extension website – http://cetehama.ucanr.edu– is attracting a good deal of attention from growers, he notes. It provides a wide range of tips and techniques on such topics as monitoring crop stress, irrigation system performance and irrigation scheduling.

The recent cool temperatures and lack of any significant rainfall this month has minimized current disease threats for many Tehama County growers.

“The walnut orchards are sure looking clean right now,” Buchner says. “Although we’re on the tail end of the threat from walnut blight, this disease could still be an issue given enough rain. So far, growers have been doing a good job getting their fungicide sprays well up into the canopies, and I’ve seen very few blighted trees this season.”

In terms of insect pests, growers are focusing more attention on controlling walnut scale which appears to be associated with development of Botryosphaeria in walnuts, he notes..

All in all, at least in his area, this walnut season has gotten off to a promising start. “Growers here seem pretty upbeat,” Buchner says.

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