SW Michigan Fruit Update
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Southwest Michigan, June 30, 2009

Mark Longstroth, Bill Shane, Diane Brown-Rytlewski

Weather

Last week’s weather was hot and dry.  High temperatures were in the high 80s and lows were near 70.  Storms last Thursday missed the area so no rain fell last week.  Soils are drying out.  Cooler temperatures are forecast for this week, with highs in the 70s.  There is a chance of showers during the week and a return to seasonal temperatures by the weekend.

Southwest Michigan Growing Degree Day Totals March 1 through June 28, 2009				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	1500	1300	929	889
Fennville:	1413	1175	819	793

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

Insects

Japanese beetles have emerged.  Normally waves of this pest emerge following significant rains.  We also expect the picture wing fruit flies will emerge following rains during warm weather.  This group of flies includes the cherry fruit flies, walnut husk flies and blueberry and apple maggots.  These flies are differentiated by their wing patterns and actually include some beneficial insects that attack weeds.  San Jose scale crawlers are out. 

Tree fruit

In Apricots fruit are ripening and the harvest of early varieties has begun.  Sprays to control brown rot should be applied when fruit colors and softens as ripening begins.

Peach fruits are about 2 inches in diameter.  Rusty spot can be found.  Second generation of Oriental fruit moth is flying, but the cool weather forecast will probably reduce the flight until warmer weather returns later in the week.  I do not expect significant egg laying from this flight until the weekend.  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 is underway.  Growers need to protect sweet cherry fruit from brown rot and cherry leaf spot.  Fruit brown rot and alternaria spot are fairly common especially on fruit that cracked during rains a few weeks ago.  A few more Eastern cherry fruit flies were caught again last week.  Insecticides should be applied to varieties that will still be on the trees next week.

Tart cherries are red.  Most growers have applied Ethrel and harvest of a few southern orchards will start before the 4^th of July but most will begin next Monday July 6.  ‘Balaton’ cherries are coloring.  Unsprayed tart cherries have been almost defoliated from cherry leaf spot. 

In Plums, European plums are about an inch in diameter.  Oriental plums are over an inch in diameter.  San Jose scale has been a problem in plums for several years.  This pest can mark the fruit, but also causes tree decline and death in some cases. Treatment for San Jose scale crawlers should be applied where this pest has been a problem.  Only the most vigorous shoots are still growing so growers can reduce fungicides to control black knot. 

Apple fruits are generally 1.75 inches in diameter.  Apple scab is common.  By now the waxy fruit is resistant to scab but fungicides to reduce leaf scab, sooty blotch and flyspeck should be included in cover sprays.  Fireblight symptoms continue to increase and spread.  Some orchards are severe.  Growers with fire blight in the orchard blocks should control on sucking insects such as aphids and leafhoppers, which spread fire blight to new trees.  Codling moth trap catches were variable during last week’s hot weather.  Codling moth Biofix was May 20 for most of the region and many growers are applying their second sprays.  We have accumulated about 600 GDD since codling moth Biofix.  While we are close to the end of the first flight, we expect a surge in egg hatch this week following the high numbers trapped two weeks ago.  Obliquebanded leafroller egg hatch begins when we accumulate 400 to 450 GDD after biofix.  We are now at 500 GDD.  Scout shoot tips for signs of feeding.  Stippling from white apple leafhoppers and hopper burn from potato leafhoppers are easy to find.  Green apple aphid numbers are building in terminals.  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 emergence is forecast for June 29 and we normally catch our first apple maggot fly around the beginning of July.  Apple maggot traps should be out. 

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

Small fruit

In Blueberries, the harvest of early varieties such as Bluetta, Weymouth and Duke has begun.  Growers should maintain protection against anthracnose fruit rot.  Shriveled berries due to cherry and cranberry fruitworms are common is some fields.  Cherry fruit worms normally attack single berries while cranberry fruitworms injure several berries.  Blueberry maggot emergence is forecast for June 28 and blueberry maggot traps should be out.  We are finding small leafroller larvae in some fields.  Look at the Michigan Blueberry IPM Newsletter posted by Paul Jenkins at the Berry Entomology Lab.

Grape bloom is ending in vinifera grapes.  Berries in juice grapes are buckshot sized and close to berry touch.  While phomopsis leaf lesions are easy to find, few other disease symptoms can be found.  Black rot leaf lesions can be found on leaves of abandoned grapes.  A few Japanese beetles are out and can be found in wine grapes. Most growers will be applying their second post bloom spray at the end of the week.  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 June 28, 2009. 

Strawberry harvest has ended and many 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.