No stress the 'sweet spot' for walnuts

With walnuts, stress begins to affect tree growth and other processes before the leaves start to wilt. So explained Ken Shackel, a UC-Davis plant biologist, during a University of California Cooperative Extension short course on walnut irrigation held Friday at the Red Bluff Elks Lodge. The course was attended by about 60 local farmers.

Shackel said it's important to use pressure chambers and other devices to monitor moisture levels, much like with a blood pressure monitor for humans.

In some walnut orchards, researchers tried moderate deficit irrigation, which has helped improve the quality of almonds and prunes and saves water and pruning costs.

But the practice resulted in bit yield losses by the third year, as walnuts are much more vulnerable to low to mild stress than are almonds or prunes, Shackel said.

"This would argue that no stress is the sweet spot for walnuts," he said.

For my complete story, check CapitalPress.com later this week.