Damage to California’s blossoming almond crop from the March 10 freeze could be more widespread and worse than many growers realize, says Eli Akel, PCA with Akel AG Consulting, Clovis, Calif., based on his observations of orchards in Madera, Fresno and Kings counties.

He estimates that anywhere from 30 percent to 90 percent of the trees in some of the orchards he has inspected suffered from the sub-freezing temperatures, depending on such factors as elevation, topography, amount of nearby vegetation and lack of wind that exacerbated the microclimate.

In some areas, temperatures remained cold enough for a long enough time to inflict substantial damage, Akel says. His logs show that freezing temperatures at two orchards in the central San Joaquin Valley persisted for close to seven hours.

Chowchilla Field Temp oF Hanford Field Temp oF
3/9/2009 18:00 43.70 3/9/2009 18:00 53.10
3/9/2009 19:00 38.90
3/9/2009 19:00 46.70
3/9/2009 20:00 36.20 3/9/2009 20:00 43.20
3/9/2009 21:00 34.20 3/9/2009 21:00 42.10
3/9/2009 22:00 33.00 3/9/2009 22:00 36.90
3/9/2009 23:00 32.60 3/9/2009 23:00 34.20
3/10/2009 0:00 31.40 3/10/2009 0:00 32.10
3/10/2009 1:00 31.40 3/10/2009 1:00 30.00
3/10/2009 2:00 30.60 3/10/2009 2:00 29.50
3/10/2009 3:00 30.60 3/10/2009 3:00 29.50
3/10/2009 4:00 29.70 3/10/2009 4:00 28.90
3/10/2009 5:00 28.90 3/10/2009 5:00 27.70
3/10/2009 6:00 28.90 3/10/2009 6:00 28.20
3/10/2009 7:00 33.80 3/10/2009 7:00 28.40
3/10/2009 8:00 54.00 3/10/2009 8:00 36.20


While the blackened inside of a nut indicates frost damage, it’s not the only sign, he notes.

“If you cut into the base of a healthy nutlet, you’ll see a clear, jelly-like substance,” Akel says. “However, if the underside of the seed coat is an off-white or yellowish color, the base of the exterior seed coat was exposed to the freezing temperature and the crop will suffer a loss in percent set.”

The full extent of any damage is not yet apparent, as some fields suffered heavily, particularly in the Chowchilla area, he says.

The Monterey variety was the least affected by the low temperature exposure. Padre, Wood Colony and Carmel varieties appear wiped out in some regions, while Fritz and Nonpareil varieties were thinned out.

In addition to the cold exposure, 30 percent to 40 percent of Nonpareil trees bloomed out well ahead of the pollinators. This variety accounts for almost 45 percent of production, he says.

Tree age and height were also a factor. “Some young fields were devastated,” Akel says. “Irrigation and soils with high moisture-holding capacity helped the hardier varieties and lessened the amount of damage on more vulnerable varieties.

“The question remains: Will any of the regions be declared disaster areas? Also, the final assessed yield may be well below the projected 1.5 billion pounds.”