Jack Frost Just Doesn't Give Up!

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Certain areas of Northeastern Ohio woke up Sunday morning to find that a hard frost had developed overnight covering turf, picnic tables and decks.  Many ornamental plants and fruit trees had swollen buds and even some scattered blooms evident.  The phone calls from concerned citizens started coming in wanting to know if all was lost regarding the fruit trees and blueberries for this year.  So I went out to see what had happened to the potential fruit crop for the coming season.

Peach bud with cold damaged ovary
Peach bud with ovary damaged by cold temperatures

There are two ways to evaluate the impact of frosts or cold temperatures on the flowers of fruit crops.  The first way to check fruit buds is to simply cut some twigs with flower buds on them and bring them indoors to "force" them to bloom.  Once the flowers are open, it is easy to use a hand lens and check to ensure the pistil (female) and stamens (male), inside of the flower, have not been damaged.  If the tissue is brown, clear or appears oil soaked, then that tissue most likely has been damaged by the cold temperatures.  Don’t just go by the appearance of the petals or bloom tissue.  I have seen trees with lovely unaffected blooms; however, both the stigma and style on the pistil was showing damage, but the ovary was still green!  Healthy tissue, undamaged by the either below freezing temperatures or damaged by ice crystal formation (frost), resulting in ruptured cells, should remain a pristine greenish-white in color. 

Peach_Bud Cold _damaged_ovary.JPG

The second way to check fruit buds is to take a very sharp razor blade and cut longitudinally through all of the bud tissues.  Again using a hand lens, one then checks for brown, discolored tissue or any area that appears to be clear or oil-soaked in appearance.  Any bud tissue exhibiting these symptoms, most likely has been damaged by the cold temperatures.

Apple bud unaffected by frost
Apple bud with healthy tissues unaffected by frost

The next time cold temperatures or frost strike during bloom, it's up to you to check out the flowers and determine if there will be fruit or not!