Another cool wet week for Southwest Michigan fruit

Rainy weather has delayed planting and spraying by fruit growers the week of April 25.

The last two weeks have been cool and rainy. Highs were in the 40s and 50s and lows in the 30s and 40s.There have been no significant freezes, but winter injury has become more apparent in some crops and areas. A rainy Good Friday (April 22) resulted in infections by apple scab and mummy berry from wetting periods of 30 hours or more with an average temperature in the low 40s. A dry weekend between rainy weeks was welcomed. The outlook for the week is for warmer but continued wet weather through Thursday. Highs will be in the upper 50s and lows in the upper40s. Fruit development has been slow except for the occasional warm periods.Soils are saturated and soil temperatures are in the mid-40s. We are falling behind in growing degree days and are now about a week behind normal. Check for the closest weather station at Enviro-weather. Winter injury from the January 23 cold is becoming apparent in peaches, wine grapes and brambles.

Tree fruit

Southern areas are much more ahead of northern areas. Trees severely affected by San Jose scale are being detected as growers notice that infested trees do not green up.

Apricots are in bloom and will be susceptible to brown rot infection in warmer rains this week.

Peaches are at pink calyx. Leaf buds are showing about a half inch green. Copper programs to suppress bacterial spot on disease prone sites and varieties can start now. The loss of fruit buds in sites away from the lake is a symptom of winter injury. Growers close to Lake Michigan report abundant fruit buds.

Peach flower buds at pink calyx.
Peach flower buds at pink calyx.

Sweet cherries show wide variations from green tip to tight cluster. Trees on Gisela root stocks are at first white.

Tart cherries buds are from green tip to bud burst. Most ‘Montmorency’ are at green tip, while ‘Balaton’ buds have opened. There is a wide variation in crop potential in tart cherry orchards.

In plums, Japanese plums are well advanced at open cluster. European plums are at white side. Spray programs for black knot control generally start before bloom.

Apples show a lot of variation between sites and varieties. Golden Delicious and other late varieties are at quarter-inch green. Most varieties are at half inch to tight cluster. Growers have sprayed 2 to 4 times for apple scab. There have been several significant infection periods on April 15 and April 22 and more are expected this week. Growers can use the scab infection tool on the Enviro-weather website to track infection periods. We are at the end of the window for the use of copper in apples. Copper application after tight cluster increases the potential for fruit russet.

Pears are at bud burst and pear psylla are out and active during sunny warm periods.

Small fruit

Grape buds are at early swell. Damage to vinifera grapes from winter cold on January 23 is apparent in low sites in frost pockets. There is still time to make an application of copper or sulfur to help reduce disease inoculum of phomopsis and other diseases. Sulfurix would be an option for control. The first Southwest grape grower meeting will be held May 11,Noon-3:00PM at the Berrien County Extension Office, 1737 Hillandale Rd. (across the parking lot from SWMREC), with lunch at noon, followed by programs. Register in advance with Linda Gustafson at the Berrien County MSUE office(269-944-4126). Contact Diane Brown for more information.

Blueberry fields are saturated and water is standing in many fields. Flower buds are bursting in many varieties and leaf buds are showing green leaf tissue that is susceptible to mummyberry shoot strike infection. There have already been several mummyberry infection periods. Early variety fruit buds are beginning to burst. The most advanced leaf buds at the tips of the shoot have about 1/8 inch of green tissue exposed. Mummy berry apothecia are emerging from the mummies. The most advanced apothecia are about 1/8 inch wide and capable of releasing spores. Most apothecia are just emerging. Growers need to be prepared to protect against mummyberry shoot blight.

Strawberries have new leavesemerging from the crown. The flower trusses are visible in the crown. With theflowers in the ground, strawberries can easily withstand temperatures below 10°F.Once the flowers get too tight bud, the critical temperature for freeze damageincreases to 22°F.

Brambles have about quarter-inch of green tissue showing. Some varieties haveleaves beginning to unfold. Winter injury is visible in many sites especiallyin blackberries. This is probably a result of the January 23 cold. Applicationsof lime sulfur will help reduce anthracnose in plantings were this disease is aproblem.

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