SW Michigan Fruit Update

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Southwest Michigan, May 6, 2008

Mark Longstroth, Bill Shane

Weather

A freeze on Wednesday April 30, with lows in the 20 to 29 F range, caused wide spread damage but the severity of damage varied from extensive to very little.  Every freeze is different.  A great deal depending on the crop’s stage of development, the characteristics of the fruit site and the duration of cold temperatures.  This freeze was radiation freeze similar to freezes in 2002, 2004 and 2006.  Apples, grapes and sweet cherries were the hardest hit.  Southern Berrien County did not get as cold as other parts of the region and suffered less damage.

Good pollinating weather with high temperatures near 70 and lows near 50 followed the freeze.  Rain fell in the region Friday, May 2.  Rainfall amounts varied greatly, from an inch to less than a tenth of an inch.  These rains represented infection events for some diseases where more than a tenth of an inch fell.  Soil moisture varies quite a bit depending on soil type. Light sandy soils are dry, and heavier soils are still very wet.  We expect cooler temperatures this week.  The forecast is for dry conditions with highs in the 60s and lows near 40.  Rain showers should begin Friday with a wet weekend. 

Southwest Michigan Growing Degree Day Totals March 1 through May 4, 2008				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Berrien Springs:	424	336	220	210
Scottdale:	410	324	211	203
SWMREC:	389	308	201	195
Bainbridge:	402	320	211	204
Hartford:	374	297	195	191
Lawton:	417	334	221	216
Grand Junction:	429	343	230	224
South Haven:	361	287	189	182
Fennville:	348	271	175	171

Tree fruit

Tree fruits were not damaged as much as one would expect from the reported lows during bloom.  Insect activity increased last week.  Oriental Fruit Moth were caught and biofixed last week on Thursday (275) and Sunday (300).  Redbanded leafroller and spotted tentiform leafminer are flying.

Apricots are in the shuck.  Shuck split has begun in early varieties.  Damage was slight on good fruit sites. 

Peach bloom is ending.  Damage is generally light at good sites in the major production area of Berrien County.  Early non-showy types were hit hardest.  Unopened flowers were not damaged.  A good crop remains for most varieties but some varieties suffered and there might be times when flow to the market is light during peach season.  Oriental Fruit Moth were caught and biofixed Sunday at 330 GDD45.  The main worry during bloom is brown rot.  This disease requires wet and warm conditions, 5 to 6 hours of wetness at 70F.  Peaches are less susceptible after bloom.

Sweet Cherries are in the shuck.  Damage seems to be variety specific, varying from heavy to light.  Better sites and later varieties suffered less damage.  Many growers have enough cherries to feed the birds; others will have a good crop.  Sweet cherries are always susceptible to brown rot.  Since the leaves are out and developed they are susceptible to cherry leaf spot.  The rain Friday May 2 began a cherry leaf spot infection in some areas.

Tart Cherries are at full bloom.  Damage is generally light.  Tart cherries seldom get blossom brown rot unless the conditions are very warm and wet.  As the leaves emerge growers need to protect against cherry leaf spot.

In Plums, Japanese plums are in the shuck and were damaged by the freeze.  European plums are at petal fall. Stanley plums are full bloom and suffered some damage.  As shoot growth begins, growers need to protect against black knot.

Apples are at king bloom.  Damage to apples was severe in some sites.  Early and late varieties were damaged and the damage seems very variety specific.  Rain on May 2, was an apple scab infection for some sites.  Symptoms from the April 19 infection should be visible.  Fireblight should not be a problem for the next few days.  Not enough heat units have accumulated since the freeze to pose a risk of infection.  Now is the time to apply Apogee sprays to reduce the spread of fire blight.  A single application at petal fall for king bloom is most effective is reducing the spread of fireblight after an infection.  To control vegetative growth longer into the season, applications are spread out over the next 6 to 8 weeks.

Pears are at full bloom.  Pear psylla are laying eggs.  Growers should protect against pear scab.

Small fruit

Blueberries are at pink bud and suffered little damage.  Early varieties are nearing bloom and a few petals were damaged and may not open. Few growers used sprinklers to protect their plantings.  Mummyberry mushrooms had dried out but I expect more to emerge after this weekends storms.  Many growers sprayed for mummyberry sprays immediately following the freeze.  Symptoms from this infection should be visible in about 10-14 days.  No mummyberry shoot strikes have been reported.

Grapes buds are opening.  Juice grapes shoots are 2 to 3 inches long with one to two leaves out.  Wine grapes are a little behind.  Damage to juice grapes in the Paw Paw area was severe.  In Berrien County damage varied.  It was not unusual to see the buds at the tip, which had burst be killed by the freeze and buds at the base of the shoot, at bud swell undamaged.  Southern Berrien County suffered much less damage.  In wine grapes, damage varied greatly by variety. Some French Hybrids were advanced enough to be hurt, but other varieties were not damaged. Vinifera grapes were at swollen bud and suffered little damage. 

Strawberry flower trusses are out and bloom has begun.  Many strawberry growers protected their crop with sprinklers.  Growers have spread straw between the rows.  Fungicides during bloom can reduce fruit rots at harvest.

Raspberry and Blackberry shoots are growing.  Damage from the freeze was minor.  In fall bearing plantings where all the shots have been removed the new primocanes are about 6 inches tall.

Cranberry beds are greening up and tip buds have burst.

Miscellaneous

Last week growers were planting trees and applying fungicide sprays.

The next Monday Fruit Update meeting will be, Monday May 12, at the Fruit Acres Farm in Berrien County.