SW Michigan Freeze May 3, 2004
May 5, 2004
For more information on recognizing frost injury in tree fruits see my Freezing Injury Page.
Weather
A frost occurred across Western Michigan on May 3, 2004. Temperatures ranged from 28 to 26 in most of the fruit sites. Lows of 25, 24 and even 22 were also reported. These freezing temperatures are in the middle of the damage range for fruit at and after bloom. Damage varies widely from site to site depending on elevation, air drainage and crop development. Southern Berrien suffered more damage. Losses across all fruit crops are consistent with 28-26 degree temps and a relatively high temperature inversion.
Tree fruit
Peach fruit were in the shuck. It is hard to assess frost damage now. The heavy bloom means that we probably did not suffer yield losses in peaches. Large fruited fruits need less flowers to become fruit for a full crop of 3" peaches. Our bloom was so heavy that we could have lost 90% of the flowers and still had a good marketable crop.
Sweet cherry fruit were at shuck split and suffered heavily from the frost with
cherries in the higher sites suffering less damage. The cherry fruit above were frozen and
have a "watersoaked" appearance after they have thawed out.
Tart cherries
bloom was ending. Tart cherries suffered lighter damage than sweet cherries and it is hard
to assess damage now. It appears that we suffered about 25% losses in the bottoms of the
trees and I feel that we suffered little loss in the upper portions of the trees. We will
know more when the fruit emerge from the shuck. The flower cluster to the right shows
little damage to the pistils inside the shuck. In some cases the style was burned by
frost but this will not hurt if the ovule ,which becomes the seed) has been fertilized.
Plums: European plum fruit are in the shuck. Japanese plum buds are at shuck split and suffered heavy damage. Growers should be applying black knot sprays. Protection needs to be maintained until the end of shoot growth.
Apples are at full bloom. Late varieties are at king bloom. While the frost caused
browning of the petals especially in Golden Delicious, a lot of the pistils are undamaged.
The picture above shows damaged petals and some of the styles in the middle of the flower
are black indicting that the flower was killed. We have lost some of the king bloom but
the heavy bloom this year means that harvest yields should still be good. The picture to
the right shows a dead king bloom and live side bloom. The picture below shows live king
bloom. The king bloom has the potential to be the largest apple fruit in the
cluster. Apple growers would prefer to set the king bloom and thin off the side bloom. But
having some live side blooms is better than losing your crop to Frost
Pollination conditions over the bloom period have alternated between hot and windy or cold and windy so pollination may be more important than this frost in determining apple yield.
Pear bloom was ending. At this time pears do not appear to be much damaged.
Small fruit
Blueberries are at late pink bud and early bloom.
In general blueberries were not damaged. During bloom, sprinkler irrigation for frost
control is effective; see the articles in April 27, 2004’s Fruit CAT Alert on protecting blueberries
from freezing damage. Frost damage was most severe in the southern areas where development
was most advanced with early varieties at full bloom. Leaves have unfolded.
Grapes
Grape shoots had several
leaves out and losses to frost were about 10 to 20%
of the shoots killed. Some vineyards in low areas and in Southern Berrien County suffered
more damage. The true extent of the injury will not be known until the secondary buds came
out. See the article on the 2002 April 23 freeze. The photo
at the right shows the pattern of the loss. grape shoots were either killed or not killed
and live shoots were located on the same cane as ones that died.
Less advanced vineyards suffered less damage. Growers should maintain protective fungicide
sprays against powdery mildew, black rot and phomopsis. Early fungicide applications as
the flower cluster emerge will prevent infection of the cluster rachis during spring
rains.
This is a veiw of a frost pocket in a grape vineyard where all the shoots were killed by
the May 3 freeze in a low area where the cold air settled. Areas that are green still have
lots of green shoots while dark areas have few green shoots. After the secondary buds
begin growth, the frost affected areas will green up and then we can assess the crop
potential of frost damaged vines.
Strawberry bloom has begun. There was light damage to the bloom where growers did not frost protect Monday morning.
Raspberries have leafed out and seemed to suffer little from the frost. Fall raspberries shoots were emerging from the ground and about 6 inches tall. It is likely that frost damage to the base of the shoots will stunt future growth and this year's primocanes will be short.
Cranberries were beginning to green up and not damaged by the frost.
