Pistachio continues to be an important crop in Kern County with approximately 50,000 acres of bearing trees and thousands more of non-bearing.

Pistachio is an alternate bearing crop, and on the West Side of the San Joaquin Valley (SJV) where most of the pistachio trees are planted, the 2010 season was expected to be a low-yielding year.

However, mature trees have larger yields than I expected, although the percentage of the nuts on the tree that are blank (nuts with no kernels) appears to be in the 15-20 percent range on many trees.

The large number of new plantings in 2005 and 2004, which will be producing the first commercial yields, will also boost production this year, as will yields of some mature trees on the east side of the Valley which appear to be in the high-yielding on-year.

The cool spring and bouts of cooler weather in late summer slowed nut growth and pushed the harvest season 17 days or so later than normal. Few trees will be harvested before Sept. 22.

The cool spring retarded the trees normal adjustment of crop load this season, resulting in larger nuts shriveling on the tree and not falling off until early summer. The cooler early season also allowed flower thrips to feed on the hulls much later into the season, causing prominent hull scaring, but this damage is only cosmetic and does not require chemical control.