Monday morning freeze caused varied damage to area fruits

This was a classic radiation freeze
with cool dry air in place and
calm clear conditions at night.

    PAW PAW - Monday morning’s freeze caused some damage to fruit in Southwest Michigan. Temperatures were not cold enough to cause widespread severe damage. Some areas and crops were hit hard and other areas suffered little damage. Michigan State University Extension Fruit Educators Mark Longstroth, Bill Shane, and Brad Baughman offered the following report.
    Last week was very cool. The week  started wet, with rain on Monday and Tuesday. Wednesday was clear and windy. Thursday was wet and rainy. Conditions were clear and windy through the weekend. High temperatures last week were in the 50s, lows were in the 30s and 40s. Scattered frosts occurred on Wednesday and Sunday, but the most significant freeze occurred Monday morning.
    According to the MSUE Educators, lows on Monday morning ranged from 35 to 25 F. Temperatures as low as 22 F were reported in some cold areas. Berrien County and areas close to Lake Michigan were generally warmer, with highs generally at or above freezing.
    Away from Lake Michigan, low temperatures were below 30. This was a classic radiation freeze with cool dry air in place and calm clear conditions at night. A light variable breeze meant that there was a weak inversion with little differences between higher and lower sites away from the lake.
    In Berrien County, the elevation differences seemed to be more important. These temperatures were cold enough to cause damage, but not cold enough to cause widespread severe damage. Some areas were hit hard by the freeze. There are many differences between sites and crops. It will be several weeks before the true extent of the damage from this freeze event is known. This freeze was probably the last freeze in Southwest Michigan.
    About four inches of rain fell in April. The wet conditions make disease control hard with wet soils and frequent long wetting periods.
    Tree Fruit: Low temperatures on Monday morning caused some damage to fruit crops in low areas and areas away from Lake Michigan.
    Apricots -  The crop is generally light.
    Peaches - In good peach sites do not appear to have suffered much from the freeze.
    Sweet cherries - Were more exposed, they suffered more from Monday’s low temperatures. Tart cherry leaves are susceptible to cherry leaf spot infection. Tart cherries were open during warm weather and good pollination conditions and the crop potential for most sites looks good. Young fruit is visible in the shuck. This fruit appears undamaged, but the effects of recent freeze may influence fruit drop latter.
    Apples - varieties range from petal fall (Red Delicious, Golden Delicious, and Gala), and 4-5 mm diameter fruit (Zestar, Macs). Apples in colder sites have suffered damage from Monday’s low temperatures.
    Small Fruit: Grape shoot growth was three to four inches long and flower clusters were exposed in Concord, Niagara, and early varieties such as Marquette. Many of these exposed shoots were frozen in Monday’s freeze.
    Damage is spotty and widespread. In many cases, frozen and healthy shoots are side by side on the cane. Assessing the damage will take some time. Where damage is severe, secondary shoots will start to grow but this will not be apparent for several weeks.  Last week, many growers applied fungicide sprays to control phomopsis. Hybrids and vinifera grapes are at late bud swell to bud burst and probably not as severely damaged by the freeze. Wine grapes are often grown in better sites with good air drainage. Juice grapes are past the stage where grape flea beetles and climbing cutworm are a concern, but these pests may still be a concern in varieties with late growth.
    Blueberries - Moved very little over the past week and leaves and flower buds turned red in the cool weather.
    Few growers can pump enough water to protect all their fields; many do not have sprinklers so there were many unprotected fields. Damage in unprotected fields is variable and depends on the site, stage of development and the actual low temperature. Mummy shoot strikes are appearing.

The Courier-Leader & Paw Paw Flashes

The Courier-Leader & Paw Paw Flashes
32280 E. Red Arrow Hwy. • P.O. Box 129
Paw Paw, MI 49079
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