SW Michigan Fruit Update
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Southwest Michigan, August 24, 2009

Mark Longstroth, Bill Shane, Diane Brown-Rytlewski

Weather

Last week was cool with highs falling from the 80s into the 60s.  The passage of several cool fronts brought showers, which dropped about an inch of rain.  Soils 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 23, 2009				Grapes, April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	3040	2621	1965	1929
Fennville:	2822	2413	1773	1748

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

Insects

Apple maggot and blueberry maggot numbers increased last week following widespread rain showers.   Trevor Nichols Station reports San Jose scale trap catch is high.  Japanese beetle adults and potato leaf hoppers are still active but numbers should be declining. 

Tree fruit

Peach,  Harvesting PF23, PF24-007, PF24C, Allstar, Glowingstar, Blushing Star, and Baby Gold 5. Quality continues to be good with relatively few split pits.  Brown rot is common in some orchards and 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.  Western flower thrip are hard to find although tarnished plant bug are common where in orchards with broadleaf weeds. 

In Plums,Fortune and Toka harvest is underway, Stanley harvest is complete. Ripening plums should also be protected from brown rot.  Apple maggot is a problem in ripening plums.  Scout for leafhopper damage from white apple or potato leafhoppers. 

Apple fruit size and quality remain good.  Williams Pride harvest is ending.  Harvesting of Paulared, Dandee Red, Chenango, and Gingergold is underway.  With the relatively cool season we expect that Macs will harvest before Gala.  Gala were starting to show some starch conversion in the core last week in preliminary tests.  Harvest of Gala is expected to begin at or shortly before Labor Day Sept 7^th.  Apple scab symptoms are fairly common, some on fruit.  Sooty blotch and flyspeck is still relatively rare.  Codling moth trap catches continue to be high in spite of cooler weather.  Oriental fruit moth trap catches are low.  Apple maggot flies are in good numbers.  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 continues.  Asian pear harvest has also begun.  Growers should protect against the second generation of codling moth, which attacks pears just before harvest.  Entries of codling moth into immature pears have been seen. Pear scab was found this week on the variety “Clapp’s Favorite”.

Small fruit

Blueberry harvest continues with hand and machine harvest of Jersey and Elliot.  Growers near Lake Michigan report good size and quality.   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. See the most recent copy of Grape IPM Newsletter at the MSU Grape current conditions webpage. 

 

    Fall raspberry harvest is in full swing. Some varieties being harvested include: Caroline, Autumn Britten, Ann, Polana, and Encore.Some varieties, such as Prelude, are producing a strong second crop. Raspberry quality looks very good.Blackberry harvests are down considerably, due to spring freeze injury (growers report about 10-15% of normal). Potato leaf hopper burn has been reported in the new growth of raspberries.  Morning dews can cause fruit rot problems such as Botrytis gray mold, so apply fungicides if needed to reduce these diseases.