SW Michigan Fruit Update
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Southwest Michigan, July 6, 2009

Mark Longstroth, Bill Shane, Diane Brown-Rytlewski

Weather

Last week was pleasant and dry.  High temperatures rose from the high 60s to the low 80s and lows were in the upper 50s.  Warmer temperatures are forecast for this week, with highs in the 80s.  There is a chance of showers during the week and continued seasonal temperatures.  Soils are becoming dry.

Southwest Michigan Growing Degree Day Totals March 1 through July 5, 2009				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	1726	1452	1041	983
Fennville:	1581	1319	923	880

You can find weather and IPM information for Southwest Michigan at the Enviroweather website. 

Insects

Japanese beetle numbers are low.  More picture wing fruit flies are emerging. Capture of cherry fruit flies and blueberry maggot have been reported.  San Jose scale crawlers are out. 

Tree fruit

Apricots harvest is underway.  Maintain protection against brown rot during fruit ripening.

Peach fruits are about 2 inches in diameter.  Rusty spot can be found.  Second generation of Oriental fruit moth is flying and laying eggs.  We expect the end of egg laying for the second generation at about 2200 GDD base 42.  Growers who have not applied trunk sprays for borers should do so in early July.  Treatment for San Jose scale crawlers should be applied where this pest has been a problem.

Sweet cherry harvest continues in late varieties.  Growers need to protect sweet cherry fruit from brown rot.  Fruit brown rot and alternaria spot are fairly common especially on fruit that cracked during rains a few weeks ago.  Few Eastern cherry fruit flies have been caught in the region this season.  Insecticides should be applied to varieties that will still be on the trees next week.  Harvested trees should receive treatment for cherry leaf spot with long lasting protectant materials such as Bravo.

Tart cherry harvest is underway.  Unsprayed tart cherries have been almost defoliated from cherry leaf spot.  Harvested trees should be treated for cherry leaf spot.

In Plums, European plums are about an inch in diameter.  Treatments for San Jose scale crawlers should be applied where this pest has been a problem.  Scout for leafhopper damage from white apple or potato leafhoppers.

Apples are generally 1.5 inches in diameter.  Fireblight symptoms continue to increase.  Some orchards are severe.  Sucking insects such as aphids and leafhoppers can spread fire blight to new trees.  Codling moth trap catches are generally down.  Codling moth Biofix was May 20 for most of the region and we have accumulated about 750 GDD since codling moth Biofix.  We are close to the end of the first flight (1000 GDD post biofix).  Obliquebanded leafroller egg hatch began last week at 400 to 450 GDD base 42 after biofix (June 8).  We are now at 750 GDD.  Scout shoot tips for signs of feeding.  Leaf feeding pest such as white apple leafhoppers, potato leafhoppers and apple aphids are easy to find.  Mite numbers are building.  The treatment threshold for European red mite in late June and early July is 5 mites per leaf.  Oriental fruit moth trap catch is up signaling the emergence of the second generation.   Apple maggot traps should be out.  We normally catch our first apple maggot fly at the beginning of July.

Pear fruit are 1.75 inches in diameter.  Pear Psylla is the only pest of interest at this time.

Small fruit

Blueberry harvest has begun in earnest.  Large picking crews are hand picking early season varieties in Van Buren County.  Fruit size and quality are excellent. Growers should maintain protection against anthracnose fruit rot.  Shriveled berries due mummyberry are common is some fields.  Blueberry maggot flies were caught late last week.  Japanese beetle numbers are low.    Look at the Michigan Blueberry IPM Newsletter posted by Paul Jenkins at the Berry Entomology Lab.

Grapes are nearing berry touch.  We are nearing the 1200 GDD base 50 from April 1.  This point is used to estimate the time when grape berries are at 50% of their size at harvest.  Growers should estimate what their potential crop is at this point.  It appears that we have a very heavy crop and we may not have the late summer heat to ripen a very heavy crop.  The earliest areas in SW Michigan will reach the 1200 GDD point early next week.  There is a model on the Enviroweather website to predict the 1200 GDD date.  While phomopsis leaf lesions are easy to find, few other disease symptoms can be found.  Black rot fruit infections have been found on backyard grapes.  Few Japanese beetles are out.  Grape leafhopper nymph numbers are low.  See the most recent copy of Grape IPM Newsletter at the MSU Grape current conditions webpage.  Here is a link a table of SW Michigan’s Grape Growing Degree-Days from April 1 to July 5, 2009. 

Strawberry growers have begun renovation.  Renovation should begin as soon as harvest ends.

Raspberry harvest is beginning.  Wilting shoot tips may be due to girdling by the raspberry cane borer.  Fungicides should be applied to protect the fruit and suppress leaf diseases.  Japanese beetles have been reported in raspberries.