SW Michigan Fruit Update

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Southwest Michigan, April 15, 2008

Mark Longstroth, Bill Shane, Greg Vlaming

Weather

Cool temperatures with highs near 60 and near 40 slowed down plant development.  We are at the lowest GDD accumulation since 1996 and are about 2 weeks behind recent years.  It rained most of last week and soils are wet.  Fruit buds on most crops are swollen. With bud growth, there is increased danger for freeze damage.  Freezes Monday (low 27) and Tuesday (low 25) mornings caused only a little damage to stone fruit.  Even with our delayed spring growth, there is still a good chance of temperatures into the upper twenties into May, which could cause damage to developing buds and flowers.  The forecast is for warmer conditions with rain showers Thursday.

I changed the links below to the Enviroweather webpage for the automated weather stations.

Southwest Michigan Growing Degree Day Totals March 1 through April 13, 2008				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
Berrien Springs:	125	86	44	34
Scottdale:	117	81	41	33
SWMREC:	107	74	38	32
Bainbridge:	108	75	39	32
Hartford:	92	63	32	28
Lawton:	112	79	42	37
Grand Junction:	116	80	42	36
South Haven:	91	64	33	26
Fennville:	84	55	27	23

Tree fruit

Tree fruit buds are swollen and we are beginning to see green tissue.  Mark Whalon reports that plum curculio adults were active on April 1 in East Lansing.  Temperatures were too chilly for insect activity last week.  Now is the time to put out Oriental Fruit Moth and Redbanded leafroller traps.

Apricots buds are at red bud to first white.  At this bud stage, injury would occur at temperatures in the mid 20s. 

 

Peaches buds are at swollen bud, to calyx green.  At this bud stage, injury would occur at temperatures in the low 20s.  As fruit buds become more swollen it is easier to determine the buds that were killed by winter cold.  Winter damage was generally light in the major peach producing area.  Green leaf tissue is emerging from leaf buds.  It is too late to apply protectant sprays for peach leaf curl.  Recent rains were certainly infections for this disease.  There is probably some benefit to catch up sprays to reduce peach leaf curl where earlier sprays were missed.  The most effective material would probably be chlorothalonil.  Now is the time to put out pheromones for Oriental Fruit Moth for mating disruption.  Mating disruption has been very successful against this pest.

 

Cherry buds generally are at green side.  Some tart cherries are at green tip and suffered a bit of damage from the freeze Monday morning.  At this bud stage, injury would occur at temperatures in the mid 20s.  The window for applying copper as a dormant spray to sweet cherries to reduce bacteria canker is ending.  Copper can still be applied to tart cherries, which can tolerate copper very well.

 

In Plums, Japanese plum buds are at tip green.  At this bud stage, injury would occur at temperatures in the mid 20s.  European plums show only a slight swelling.  At this bud stage, injury would occur at temperatures below 20. 

 

Apples are generally at silver tip.  Early varieties are at green tip.  At this bud stage, injury would occur at temperatures below 20.  We expect to see quarter inch green later this week, at the ¼ inch, bud stage, damage would occur in the low 20s.  Apples are susceptible to apple scab. Because of the mild winter, we expect scab spores from the leaf litter will be ready as soon as green tissue is available for infection.  Growers should be ready to apply scab sprays.

 

Pears buds are swollen.  At this bud stage, injury would occur at temperatures below 20.  Few pear psylla adults are out and no eggs have been found.  More adults should emerge soon when warm weather returns.

 

Small fruit

Small fruit have broken dormancy, but we are still in the window for Lime Sulfur applications in blueberries, grapes and brambles to suppress diseases that overwinter on the plant.

 

Blueberry fruit buds are swollen and leaf buds are beginning to move.  At this bud stage, injury would occur at temperatures below 20.  It is time to look for mummyberry mushrooms. Mushroom development begins about the time green tissue shows on the leaf buds and new mushrooms were reported last week.  We should see a lot of mushrooms after several warm days warm up the soil.  There is standing water in many fields.

 

Grapes are at scale crack.  At this bud stage, injury would occur at temperatures in the mid teens. 

 

New strawberry leaves are emerging.  At this development stage, injury would occur at temperatures below 10F.  Growers are applying herbicides and putting down irrigation pipe for frost/freeze protection and straw mulch.

 

Raspberry and Blackberry buds are at green tip.  At this bud stage, injury would occur at temperatures below 20.  Growers are finishing pruning.  Now is the window for Lime Sulfur applications to suppress anthracnose.

Cranberry beds are coloring up but the tip buds are still tight.

 

Miscellaneous

Growers are clearing brush.  Quite a bit of copper has been applied to stone fruit.  Some tree planting has occurred but I expect more as the soil dries out.  A lot of older cherry and apple orchards were removed during the winter and early spring.

The next Monday Fruit Update meeting will be, Monday April 21, at the Fruit Acres Farm in Berrien County.

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