Assessing Cold Damage on Fruit Crops
So the cold temperatures have passed, now how do you assess your fruit crops for cold damage?
Generally cold damage will appear in a few days after cold temperatures occur but the full extent may not be evident until temperatures warm back up and plants start growing.
I went to the Fruit Research Station in Clarksville AR today to look at their crops and see if I could find examples of damage. In Clarksville they had lows of 30° F on the 12th (last Sunday) and a low of 28° F yesterday and the day before (Wed 15th and Thurs. 16th). So their lowest temperature was only a day ago and damage may still take some time to appear. Remember that all stages of blackberry flowers (bud to full bloom) are damaged at 27° F. Blueberry open flowers can be damaged at 27° F and early berry swell at 28° F. Peaches are damaged between 21-27° F. We will have to wait and see to what extent the measured lows of 28° F hurt any of these crops.
Thus far there is only a little damage apparent and mostly only on early emerged blackberry blossoms and to early flowering blueberry blossoms. I found only a little damage to peach trees which were blooming. To accurately assess cold damage on a per acre basis 50-100 buds should be examined. See the pictures that follow to help ID what cold damage can look like. I will continue to update this with more pictures as crops continue to progress into the spring.
Here are some comments for those who have experienced cold damage on their fruit crops.
It is important to consider that thinning is still to be done and the death of some flowers at this point may not mean a total loss. Randomly assess 50-100 flowers per acre to get a good count of flower loss. Only about ¼ to 1/3 of buds are needed to make a full crop.
Damage to blueberry blossoms can lead to outbreaks of botrytis (gray mold) or stem blight if temperatures warm back up to the 60s-70s and there is moisture. Growers should be aware of this and may want to apply a fungicide spray if it gets warm and we get rain (this is forecasted in some parts of the state next week).
Blackberry and Strawberry
See notes on watching for botrytis (gray mold) under blueberry.
Strawberry Cold Damage
Blueberry Cold Damage
Blackberry Cold Damage
Peach Cold Damage
Peaches may be difficult to assess due to the fuzz on the pistil (see picture on right).
Apple (No damage seen)