SW Michigan Fruit Update
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Southwest Michigan, June 9, 2009

Mark Longstroth, Bill Shane, Diane Brown-Rytlewski

Weather

Last week was generally cool with highs near 70 and lows in the 50s.  No significant rain fell after last Tuesday (June 2).  Soils are beginning to dry out on the surface.  The warm weather and scattered thunderstorms over the weekend increased insect activity and plant growth.  Cooler temperatures with thunderstorms are forecast for early this week.  Warmer weather is forecast for later in the week and the weekend.

Southwest Michigan Growing Degree Day Totals March 1 through June 7, 2009				Grapes, from April 1
Location	GDD 42	GDD 45	GDD 50	GDD 50
SWMREC:	980	794	527	487
Fennville:	879	701	450	424

You can find weather and IPM information for Southwest Michigan at the Enviroweather website.  Here is a link a table of SW Michigan’s Growing Degree-Days from March 1 through June 7, 2009.  Our heat accumulations are lagging several days behind normal.  There is a nice set of maps accessible from the Enviroweather website showing variation from the 30 year avarage.

Insects

We have not seen rose chafers or Japanese beetle.  Potato leafhopper activity has been generally low.  Potato leafhopper numbers increase following storms from the south.  Obliquebanded leafroller was biofixed June 8.  San Jose scale flight began about May 13. 

Tree fruit

Apricot fruit are about 1.5 inches in diameter.  Growers are hand thinning the fruit.  Some trees are collapsing.

Peach fruits are about an inch in diameter and growers are hand thinning the crop.  Yellow leaves due to winter injury are common especially on plantings of low vigor.  Limb dieback due to constriction canker (Phomopsis) is showing in selected peach and nectarine varieties.  Symptoms include gumming at the base of the dead shoots near where the infection occurred last fall.  Tiny dark fungal fruiting bodies (pycnidia) of the pathogen are often seen in the gummy area.  Bill Shane is interested in cataloging which varieties are most susceptible.   Peach leaf curl symptoms remain scarce.  Tarnished plant bug injury can be found on the fruit.  Oriental fruit moth (Biofixed on 4/26) shoot strikes have appeared and we should be seeing fruit injury soon.  The flight is tapering off.  Lesser peach tree borer will emerge soon.

Sweet cherry fruits are coloring and bird feeding is a problem.  Harvest of cherries in high tunnels began last week.  We expect general harvest to begin in 10 to 14 days.  Sweet cherry fruits are especially susceptible to brown rot as they ripen, warm rains are good infection periods.  Growers also need to protect against cherry leaf spot.  Collapse of spurs and branches due to bacterial canker is a problem in some plantings.

Tart cherries are about 14 mm in diameter and beginning to color.  Cherry leaf spot lesions can be found leaves and fruit stems.  Leaf yellowing and leaf drop may be due to bacterial canker or cherry leaf spot and growers should determine which is the cause. Cherry leaf spot leasions are generally small black spots on the leaves and there will be white fruiting bodies on the underside of the lesion.  Bacterial Canker lesions are larger and often fall out of the leaf.

In Plums, European plums are 16 to 20 mm in diameter.  Oriental plums are 16 to 20 mm.  Vigorous shoot growth continues in plums and growers maintain fungicides to reduce black knot. 

Apple fruitlets are 18 to 25 mm in diameter with a few varieties such as ‘Zestar!’ about 1.5 inches.  There has been a heavy drop in the last 10 days and the crop set in most orchards is manageable.  Growers with scab in their orchards will want to continue using protectant fungicides in their cover sprays.  Waxy fruit are relatively resistant to scab infection.  The bright orange cedar apple rust symptoms are showing on apple leaves.  Fire blight symptoms continue to appear mainly in ‘Jonathan’, ‘Golden Delicious’ and ‘Rome’.  Some growers report new symptoms that may have been caused by thinning sprays, with high bacterial populations on scattered flowers.    Codling moth trap catches are up.  Codling moth Biofix was May 19 or 20 for most of the region.  We had a sharp drop off in trap catches two weeks ago and then a strong flight this last week.  Where trap catches were low to begin with and plum curculio sprays were applied soon after or during the initial trap catches sprays timed for 350 GDD after biofix would be in order.  In other words, so few moths flew that there aren’t any eggs out there to hatch.  Sprays would be better focused on the moths that flew last week than the few moths that were out three weeks ago.  We are about 300 GDD base 50 since Biofix.  White apple leafhopper feeding can be seen.  Spotted tentiform leafminer mines are visible.  European red mites are out but numbers are low.  Oriental fruit moth trap catch numbers are way down signaling the end of the first flight. We expect to see oriental fruit moth entry in apples next week. 

Pear fruit are 18 to 22 mm in diameter.  Pear Psylla is hard to find.

Small fruit

Blueberries fruit are pea sized and bloom is finished in most fields.  Where there is still bloom in the field growers should apply fungicides to protect against mummyberry in the fruit.  Inspection of young plantings shows a lot of phomopsis shoot infection that growers are mistaking for winter injury.  Dead black shoots and buds are probably phomopsis injury.  Where the fruit buds are still green the likely cause is winter injury.  Now is also the timing of anthracnose fruit infection, so fungicides should be included in cover sprays after bloom.  Virus symptoms of shoestring and mosaic are easy to find.  Growers should apply insecticides to protect against cherry fruitworm and cranberry fruitworm where they are a problem.  Cranberry fruitworm biofix was May 20 in some areas.  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 has begun.  Niagara bloom began Sunday, June 7, and Concord bloom will begin soon.  Wild grape bloom began May 28 in southern Berrien County and a week later (June 4) in eastern Van Buren.  Wild grape bloom is used to start the grape berry moth model on the Enviroweather website.  Downy mildew and phomopsis lesions have been found in Niagara.  We expect to see rose chafer soon.  Grape berry moth sprays should wait until the end of bloom.  Grape Leafhopper adults can be found.  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 7, 2009. 

Strawberry harvest is under way. 

Raspberry and Blackberry bloom are winding down.  Avoid using insecticides during bloom.  Sawfly and leafroller larvae can be found on the leaves.

Miscellaneous

The next Monday Fruit IPM Update meeting will be, Monday June 15, at the Fruit Acres Farm in Berrien County.  The final Monday meeting will be June 29.  

There is an upcoming Blueberry IPM meeting on Thursday, June 11 at 6 to 8 PM, at Carini Farms, 15039 Port Sheldon Rd., near West Olive.  The following Thursday, there is a Blueberry weed control demonstration tour at the Getzoff Farm, 7093 116th St. near Fennville.  .