April 11, 2012
AMES, Iowa — The second night of cold temperatures across Iowa took a toll mostly on fruit crops, Iowa State University horticulture experts reported.
Ajay Nair, extension vegetable specialist, noticed damage to fruit blossoms at the Horticulture Research Station near Gilbert after the first night, April 10, and temperatures were even colder April 11. Pictures of the damage he found are available at: http://iowavegetables.blogspot.com/
Paul Domoto, extension fruit specialist, said the temperature dipped to 20 degrees F at the horticultural station, a temperature that damages plants but especially those near the ground, like strawberries. Strawberries are most vulnerable at bloom, however, only the earliest cultivars have reached this stage of development.
He said grape vines also would suffer damage to emerged shoots, but dormant, secondary buds will replace the injured shoots, and depending upon the cultivar characteristic, have the potential to produce a near-normal crop.
Nair said vegetable growers in central Iowa held back planting most of their crops to prevent losing extensive plantings to the potential cold. Some had taken a chance and planted a few rows. Some vegetables, such as lettuce and spinach, are more hardy, but are still susceptible if the temperatures fall into the 20s.
The problem with the fruit crops is that the early spring weather sped up blooming, which is a particularly sensitive stage for the plants. Domoto said although there has been damage it's too early to say how bad the freezes were until growers can assess the conditions in their areas, because site conditions and stage of bud and/or shoot development will have a significant influence on the extent of injury.
Nick Howell, superintendent of the Horticultural Research Station, doesn't expect much of an apple crop because of the freezes, and there was "significant damage" to the station's vineyard and strawberries. Apple trees typically are "in jeopardy" until the middle of May, he said.
Unfortunately, Howell said the expense of pest management in the apple orchard must be maintained even though there are few, if any, apples produced.