SW Michigan Fruit Update

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Southwest Michigan, April 29, 2008

Mark Longstroth, Bill Shane

Weather

Eleven days of warm temperatures with highs in the 70s and lows near 50 moved plant growth quickly.  Most plants are greened up and many new leaves have emerged.  Soils began to dry out quickly with the warm, dry, windy weather.  Significant rain fell in the Berrien County and the southwest portion of the region Saturday, May 19.  A little more rain fell Thursday, April 24 and Saturday, April 26.  Rainfall amounts were generally light, less than a tenth of an inch, and these rains represented marginal infection events for some diseases.  With the warm weather, our GDD accumulation has moved close to average.  The passage of cold fronts Sunday and Monday brought cooler temperatures.  Morning temperatures Monday fell to freezing and below causing light damage to fruit.  Tuesday morning was warmer, but Wednesday morning is forecast to fall to 25 F.  Freeze injury would occur at temperatures below 29 to the mid 20s depending on the crop, so we anticipate damage in the frost prone areas.  We expect cool temperatures week.  The forecast is for dry conditions with highs in the 50 and 60s and lows near 40.  Rain showers should begin Friday with a wet weekend. 

Southwest Michigan Growing Degree Day Totals March 1 through April 27, 2008				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Berrien Springs:	351	276	181	171
Scottdale:	336	265	172	164
SWMREC:	321	253	165	159
Bainbridge:	333	264	174	167
Hartford:	310	246	162	158
Lawton:	347	277	183	178
Grand Junction:	353	281	188	182
South Haven:	293	233	153	146
Fennville:	282	219	141	137

Tree fruit

Tree fruits are blooming and would be damaged by temperature below 28F.  Insect activity increased last week.  Oriental Fruit Moth were caught and biofixed last week.  This was only a light flight and the cool weather has shut down the traps.  We often see this where we get biofix and then cool weather shuts down trap catch.  Unless you are monitoring your own orchards and caught a significant number of moths we recommend that early season Oriental Fruit Moth control s be timed on Biofix timed on moth catch after this cool period.  Redbanded leafroller and spotted tentiform leafminer are flying.

Apricots were blooming last week and are now generally in the shuck.   

Peaches are blooming.  Oriental Fruit Moth were caught and biofixed last week.  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 Cherry bloomed last week and the leaves are emerging.  Sweet cherries are very susceptible to brown rot and easily get the disease through their development.  Once the leaves are out and fully developed they are susceptible to cherry leaf spot.

Tart Cherries are blooming.  Tart cherries seldom get blossom brown rot unless the temperature conditions are very good.

In Plums, Japanese plums bloomed last week and are now at petal fall.  European plums are blooming. Stanley plums are beginning to bloom.  As shoot growth begins, growers need to protect against black knot.

Apples are at pink.  King bloom of early varieties such as Idared and Zestar are open.  Rain on Saturday, April 19, at green tip, was an apple scab infection for Berrien County and much of the surrounding area. Symptoms from this infection should be visible at the end of the week.  For the rains last week the wetting periods and the temperature were marginal for some areas with the wetting period being a little short for the temperature, so infection could easily have occurred in your orchard if it was wet longer or a little warmer.  Prebloom scab sprays are effective in completely covering the flower and stems in the cluster.  It is harder to get good coverage inside the flower cluster, after blossoms have opened.  Prebloom pink sprays are also focused on leafroller larvae, spotted tentiform leafminer and rosy apple aphid control.

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

Small fruit

Blueberry fruit buds are pink bud.  Early varieties are nearing bloom, Bluecrop is at early pink bud and Jersey is at bud burst.  The cold temperatures forecast to a low of 25F are low enough that they would only cause widespread damage in fields nearlng bloom.  I would only use sprinklers in my earliest fields. New shoots are growing.  Mummyberry mushrooms are out and last Thursdays rain was a mummyberry infection in some areas, with 8 hours of leaf wetness at about 60F.  Mummyberry sprays immediately following freeze events are very effective.

Grapes buds are opening.  Juice grapes are at bud burst and wine grapes are a little behind at swollen bud development stages.  At this bud stage, injury would occur at temperatures in the high 20s.  There is still time to apply dormant sprays of copper, sulfur to varieties that are not sensitive to these materials.  This cool weather will slow grape bud development and increase the likelihood of cutworm damage.

New strawberry leaves are out and flower trusses are emerging from the ground in southern Berrien.  If the flower buds are in the ground they will be damaged at 10F.  Once the buds emerge they are damaged at temperatures below 20F.  Many strawberry growers protected Monday night using sprinklers.

Raspberry and Blackberry leaves are unfolding and new primocanes are emerging.  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 are swelling and beginning to burst.

Miscellaneous

Lots of bees have been moved into the area to pollinate crops.  Last week growers were planting trees and applying fungicide sprays.

The next Monday Fruit Update meeting will be, Monday May 5, at the Fruit Acres Farm in Berrien County.