SW Michigan Fruit Update

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Southwest Michigan, July 1, 2008

Mark Longstroth, Bill Shane

Weather

Last week's weather was cool and dry with highs in the mid 80s F, and lows in the 50s and 60s F.  A few light showers passed through the region midweek and another group deposited approximately 0.5 inch on the weekend.  Soils in the middle and south end of Berrien County are becoming dry but the Allegan County area has had above normal rainfall. 

Tree fruit

Insect activity is favored by warm temperatures. Mite numbers are increasing but not a problem in most sites.  Oblique banded leaf roller larvae are becoming scarce as the overwintering larvae pupate. Tarnished plant bug and plum curculio damage is significant in some tree fruit orchards.  Adult rose chafer and Japanese beetles are continuing to emerge. Aphid numbers are building.  Immature stink bug are becoming easier to find.  The Michigan Department of Agriculture and the USDA are again sampling peach, plum, apricot, and nectarine trees for plum pox, with emphasis on Berrien County.  The USDA is responsible for non-commercial sampling and the MDA focuses on commercial fruit orchards.

Apricot fruits are 1.5 to 2.5 inches in diameter. 

Peach fruit are about 1.5 to 2 inches in diameter.  Pit hardening is underway, so fruit are becoming more resistant to rusty spot.  Powdery mildew and bacterial spot but not peach scab, have been reported.  Both tarnished plant bug and plum curculio damage are present.  Plum curculio damage is more common in nectarines than in peaches.  Weed spraying and mowing can drive tarnished plant bug into peach trees.  Watch for western flower thrip when hot weather returns.  The estimated start of significant commercial Red Haven peach harvest for Berrien County is August 6, according to a degree day model by Bill Shane.  This is approximately 8 days later than last year. 

Sweet Cherry harvest is in full swing with mid season varieties such as Hedelfingen being picked in some places. Cool dry weather has suppressed brown rot infection for most of the areas.  Some fruit cracking has occurred but is generally not a problem.  Brown rot requires warm, wet conditions, 5 to 6 hours of wetness at 70F and growers should be prepared to protect against this disease at harvest.  Rains this past weekend were cherry leaf spot infections in some areas. 

Tart Cherry fruit coloring has been slowed by cool weather.  Fruit on outside of tree are red with most interior fruit ranging from straw colored to nearly full red.  Mechanical harvests will generally begin after the 4^th of July weekend.  Recent rains were a cherry leaf spot infection.  Few cherry leaf spot symptoms have been reported.  Eastern cherry fruit fly were caught the last week of June in Berrien County.

Plums are almost an inch in diameter and the pits are hard.  Shoot growth has stopped and growers no longer need to protect against black knot.  Plum trees also need to be protected from the peach tree borers.  Growers should scout for white apple leafhopper.

Apples are 1.5 to 2 inches in diameter.  Some varieties such as Red Delicious and Empire have a light crop.  Growers with active scab should continue to protect against scab infection.  When fruit develop waxy coat they become more resistant to scab.  Fire blight infections are larger and easier to find but overall is relatively light for the region.  There is little oozing due to the dry conditions.  Trap catch for codling moth still remains high in some orchards.  We are now in about midway through egg hatch.  Obliquebanded leafroller adults were trapped June 9 and egg hatch is expected to be underway.  Spotted tentiform leafminer trap catches are high.  The damage threshold is approximately 2 mines per leaf for this generation.  White apple leafhoppers are still scarce.  European red mites are causing bronzing in a few trees in a few locations.  Red spots on apple fruit due to San Jose scale crawlers are showing up in a few area orchards. Careful monitoring at this point can indicate whether a spray is needed to prevent significant fruit damage and population growth of scale. Scale is being reported more frequently nowdays in SW Michigan.  Green aphid populations are climbing.  Young trees should receive sprays to kill Potato leafhoppers.  Dogwood borer moth began emerging in mid June, indicating the need for trunk sprays in orchards with burr knots attractive to the insect.  See end of newsletter for announcement of apple high density tour in the Grand Rapids area on July 10^th.

Pears are about 1.5 inches in diameter with June drop ending.  Pear psylla numbers are generally low.  Fire blight can be seen in the area but is not generally a bit problem.

Small fruit

Blueberry fruits are beginning to color.  Crop load is generally good to excellent. Harvest of early varieties is underway in a few fields.  Cranberry fruitworm egg hatch is ending.  Fruitworm feeding damage is easy to find in most fields.  Look for shriveled blue berries in the clusters of green fruit.  Cherry fruitworm only attack single fruit while cranberry fruitworm will move to other fruit in the cluster.  Preharvest fungicide sprays should target alternaria and anthracnose.  Blueberry maggot traps should be out. 

Grape berries are BB to 1/3 inch diameter size.   Rose chafer numbers are declining but they can still be found feeding on late blooming clusters of the secondary and tertiary buds.  Grape leafhopper can be found in many vineyards.  Insecticides to control grape berry moth should be included in the post bloom fungicide sprays.  Grape berry moth trap catches are up and larvae can be found feeding in the fruit clusters.  Wine grapes need to be protected from potato leafhoppers.  Fungicides in the immediate post bloom period should target all four major fruit diseases; powdery mildew, downy mildew, black rot and phomopsis.  So far phomopsis is the only disease that is easy to find in vineyards.  Wine grape growers also need to apply sprays to control botrytis bunch and berry rot.  Concord grape berries are predicted to be at 1/2 of their final weight at 1200 GDD (Base 50F) past April 1. This often corresponds to 25 days past bloom.  Current GDD sum is approximately 800 to 1000, depending on the location.

Raspberry and Blackberry fruit are coloring.  Some fruiting canes are looking weak due to winter injury.  Plants on sandy ground are showing signs of drought stress.  Growers should be scouting for Japanese beetles, raspberry sawfly larvae and leaf roller larvae.  Raspberry sawfly eats the leaves between the veins--look for small green bristled worms under the leaves.  Leaf rollers curl and web the leaves together.  Raspberry cane borers are laying eggs; look for wilting shoot tips and a ring of parallel girdles at the base of the wilting.  The egg is laid between the girdles.  Primocanes in fall bearing raspberries are 18 to 24 inches tall.

Strawberry harvest has ended for most June-bearer type varieties.

Cranberries are in full bloom.

Upcoming Meetings

The next Monday Fruit Update meeting will be, Monday July 7, at the Fruit Acres Farm in Berrien County.

Saskatoon Workshop, Thursday July 3, 2008, 10:00 AM to noon at the Leslie Putney U-Pick Berry Patch, 7603 Love Road, Benzonia 49616.  Those interested in an update on the selection, planting and marketing of saskatoons (also called June berries) are invited to this on-site workshop.  Mr. Putney planted 60 saskatoon plants in the spring of 2005.  This will be the first significant fruiting season for these plants.  There is no charge for this educational program.  Berries should be ripe enough to taste test.  Refreshments will include coffee, juice, and homemade Saskatoon berry crisp.  RSVP by calling Cathy at the Benzie MSUE Office (231-882-0025).

Apple high density workshop tour on Thursday July 10th at 1 pm starting at RidgeView Orchards at 3625 18 Mile Road, Kent City, MI. Special guest Terence Robinson, Cornell University. Stops include tall spindle and vertical axe. Check code-a-phone for changes, 616-451-8064.  RSVP by July 1 to Donna at 800-767-1345, or email: stewar28@msu.edu.  Dinner will be served at 5 PM

A strawberry black root rot and renovation meeting will be held July 10, 2008 6:00 PM to 8:00 PM at the DeLange's Redberry Farm, 5723 Port Sheldon Road, Hudsonville, Michigan. 

The annual Viticulture Day at the Southwest Michigan Research and Extension Center will be July 30.  The cost is $20 before July 18 and $25 after July 18.  A registration form is available at the Van Buren County MSUE Website; http://web1.msue.msu.edu/vanburen/vitregform.pdf

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posted: July 8, 2008