A month before the expected start of bloom, walnut trees in San Joaquin County appear to be good condition for another production year, says University of California Extension Farm Advisor Joe Grant.
The trees have had enough chilling hours since the first of last November to completely release dormancy for normal bloom, nut set and quality, he notes. Most of those chilling hours accumulated in December and January, but recent cold temperatures are also adding to the total.
“We’ve had pretty good chilling this winter, with no severely cold temperatures,” Grant says. “In this area, depending on the year, we like to have from around 800 to 1,000 total hours of chilling, and we’re getting close to that now.
“Also, we’ve had decent rainfall this winter, so the orchards soils are getting recharged with water to begin the season.”
Farther north, it looks like the walnut trees in Sutter County also will have had a sufficient number of chilling hours for the months of November, December, January and February.
“No one here is talking about chilling hours being a problem this year,” says Farm Advisor Janine Hasey. Nicolaus CIMIS Station in southern Sutter County reported a cumulative total of 895 hours of temperatures below 45 degrees from Nov. 1, 2009, through Feb. 28. That’s lower than last winter’s unusually high total of 1,254 chilling hours for the same period and compares to the 1,102 total chilling hours for 2007-2008, 1,159 total chilling hours for 2006-2008, and 837 total chilling hours for 2005-2006.
San Joaquin County walnut growers are looking for another high-production year, following two straight large crops. “A lot of young orchards are still in the process of developing toward full production,” Grant says. “The big question on peoples’ mind is, will we be able to market all of it?”