Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
We are finally seeing bloom in fruit crops. Plums and apricots are in mid-bloom, peaches and nectarines are just starting to bloom. This is about 2 weeks later than the average.
As bloom occurs, winter damage to buds will become evident. Cold susceptible plants such as blueberries, wine grapes, peaches, blackberries and nectarines can have bud damage when winter temperatures drop below -10°F. There is a lot of variation between grape varieties. Many of the European wine grapes will have damage between zero and -10 F, hybrids and American types can withstand lower temperatures. Other fruits are more cold-hardy. Cherries and European plums can withstand -20 to -25°F and apples and pears go to -25°F without damage. Delaware had temperatures approaching -10°F in some areas. Initial observations indicate that sensitive peach and grape varieties have bud damage.
Fruits that were under stress in 2013 may also show more winter injury. We had significant water damage in lower areas of fields last year and trees, vines, or canes with root damage from waterlogging may also have increased winter injury. Trees with high or excessive fruit loads in 2013 may also show increased winter damage.