If trees aren’t growing well, check the trunks, Tim Smith advises.
The Washington tree fruit industry has been lucky to see relatively little damage from the big November 2010 freeze so far, though some injured trees can take two years to succumb, says Tim Smith, Washington State University educator.
“We suspect there will still be some trees dying this year as a result of the 2010 cold snap in November,” he said during the recent North Central Washington Stone Fruit Day.
“If you have a tree that looks real funky—and often apricots will wait a year before they die—check the trunk and take a look under the bark, and if it’s all brown and dead and dry, then you know what’s doing it,” Smith said.
The cold snap came around November 23, after several days of warm weather. Temperatures in some parts of the state suddenly dropped as low as -18°F. Industry veterans recalled that it was similar to a freeze in 1955 that killed many trees and feared a repeat.
Smith said the trunk is the part of the tree that’s most vulnerable in the fall. Some flower spurs were damaged, but few flower buds. Washington produced its second-largest cherry crop ever in 2011.
If the wood under the bark looks chocolate brown, the tree is likely doomed. Where the wood is light brown, it will probably survive. The question is, how brown does it have to get before all the cells are dead, Smith said. “It turns out, pretty brown.”
Many trees will lay down new wood, leaving only a brown ring where they were damaged.
The fact that last spring and summer were much cooler than average helped minimize the damage, he said. “We had low stress on the trees for the first part of the growing season, and there were a lot of trees that were injured that were capable of recovering in those circumstances. If we’d had a hotter-than-normal year, we would have seen more trees die. I think we lucked out.”
Young plantings did get hammered, Smith said, and many acres were removed. Some trees were only killed to ground level and grew suckers from the crown. In one large young planting at Royal City, suckers were trained up the trellis to regrow the trees.
Replacement trees were unavailable, because nurseries suffered major damage from the freeze, he said. “It’s hard to get a nursery tree to plant now."