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December 2008


There are three critical times growers need to protect crops against cold injury:

• Spring’s late frosts (early growing season)

• Autumn’s early frosts (late growing season)

• Winter’s very cold temps (dormant season)


The following is a reprint from the December 2004 newsletter: I’ve cut quite a few stone fruit buds in Mesa and Delta counties the last several weeks.  The early January temps for most of your orchards was in the neighborhood of –4°F to –5°F.  There were a few spots that hit the  -8° F to  –10°F mark.  That 4 to 5 degree difference had a considerable impact.   In most orchards you can find a dead bud here and there from natural mortality.  In the area’s that were 4 to 5 degrees colder there is a different story to be told.  The damage is far more evident with some varieties surviving better than others.  As this industry moves more and more from apple and pear acreage to stone fruits, the third period of potential cold injury becomes more of a factor.


Over the last three winters I've collected peach buds and had them tested to determine how hardy they are at various points through the winter.  The following  information is a recap of those tests.   A quick look will reveal the “cliff” that occurs somewhere between -5°F and – 10°F. 



A note of thanks to Harold and Horst at CSU's Orchard Mesa research center for the technical expertise and equipment to run the tests.


The following is from an article published in Ontario Canada: “ Historically, significant winter damage occurs approximately 1 year in 10 in Ontario. However, the winters of 2003, 2004 and 2005 all had sufficiently cold temperatures resulting in observed vine and tender tree fruit bud injury.   Growers with wind machines harvested near normal crops in 2005. Those growers nearby  without machines experienced total crop failures.  Other management options help protect these crops from cold injury, but many growers consider installing wind machines one of their best long-term management strategies.  There is anecdotal evidence that on the very rare nights when it is calm, but with little to no temperature inversion, air movement created by a wind machine can help prevent cold injury. Wind  machines can raise air temperatures around plants by about half the temperature inversion difference.”


Has the point been made?  Can you afford to stay warm and cozy in your bed?  IS YOUR WIND MACHINE READY???





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