SW Michigan Fruit Update
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Southwest Michigan, August 17, 2009

Mark Longstroth, Bill Shane, Diane Brown-Rytlewski

Weather

The last two weeks were warm with highs in the 80s and lows in the 60s.  The weekend was a repeat of last week, hot with highs over 90 on Sunday.  The passage a cool front brought thunderstorms on Sunday, which dropped about an inch of rain.  More rain fell in the southern part of the region.  Soils generally have good moisture content.  We continue to lag about 10 days behind normal in heat units accumulated.  Fruit crop development seems close to normal.

Southwest Michigan Growing Degree Day Totals March 1 through August 16, 2009				Grapes, April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	2866	2468	1848	1812
Fennville:	2658	2270	1665	1640

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

Insects

Apple maggot and blueberry maggot numbers to increased last week following widespread rain showers.   

Tree fruit

Peach Harvesting PF 19, finishing up on Allstar, Coralstar, and PF17.  Harvest of PF23 and PF24-007 expected midweek.  Quality is generally good.  More brown rot infections of limbs, which originating from early season blossom infections and more recently, from infected fruit.Fungicide treatments for brown rot are needed as fruit color.  Bacterial spot symptoms continue to increase especially for susceptible varieties growing in sites exposed to wind-blown sand.  Summer dews are conducive to bacterial spot.  Watch for signs of western flower thrip on peaches.  Thrip damage appears as light brown fuzzless spots up to 1 inch in diameter usually on the blush region.

In Plums,Fortune and Castleton harvest is underway.  Stanley harvest should start soon.  Ripening plums should also be protected from brown rot.  Apple maggot is a problem in ripening plums and we can expect a strong flight following the weekend rain.  Scout for leafhopper damage from white apple or potato leafhoppers. 

Apple fruit size and quality remain good.  Earligold harvest is ending.  Harvesting of Paulared, Dandee Red, Chenango, and Gingergold underway.  Potato leafhoppers are common.  Leaf mines of spotted tentiform leaf miner.  Scab fairly common, some on fruit.  Sooty blotch and flyspeck is still relatively rare.  Codling moth trap catches are still high.  Oriental fruit moth trap catches are low.  Apple maggot flies are in good numbers following the rain.  Obliquebanded leafrollertrap catches are up.  Bronzing due to mites is fairly common.  The treatment threshold for European red mite is more than 7 mites per leaf. 

In Pears, Bartlett harvest started Sunday.  Growers should protect against the second generation of codling moth, which attacks pears just before harvest. 

Small fruit

Blueberry harvest continues with hand and machine harvest of Elliot.  Harvest of Jersey and Bluecrop is winding down.  Blueberry maggot numbers are up.  Growers should maintain protection against alternaria fruit rot and blueberry maggot.  For more information look at the Michigan Blueberry IPM Newsletter posted by Paul Jenkins at the Berry Entomology Lab. 

In Grapes, veraison has begun in early varieties.  The diseases of greatest concern now are botrytis and downy mildew.  Wet conditions spread botrytis, so susceptible varieties should be protected at veraison and whenever soaking rains are conducive to the disease.  Morning dews are good for the spread of downy mildew, so fungicides against downy mildew are required during the summer season when there are morning dews.  The third generation of grape berry moth is flying, eggs are hatching and stings and tunnels can be found on the fruit.  Japanese beetles numbers are up following this weekend’s rain.  See the most recent copy of Grape IPM Newsletter at the MSU Grape current conditions webpage. 

Fall raspberry harvest is underway.  Morning dews can cause fruits rot problems such as Botrytis gray mold, so fungicides are needed to reduce these diseases.