Southwest Michigan fruit update – Sept. 11, 2018

A cool, cloudy week helped apples but could be a problem in grapes.

September 11, 2018 - Authors: Mark Longstroth, William Shane

Niagara grapes
Niagara grape harvest should start next week. All photos by Mark Longstroth, MSU Extension.

Weather

Last week began hot and wet. The weekend in August was muggy with rain and highs near 90. The passage of a cold front Wednesday, Sept. 5, brought much cooler weather with highs in the upper 60s. Conditions were overcast for most of the week.

Despite the clouds, little rain fell during the week. Some showers moved into the region from the southeast on Sunday, Sept. 9, but brought little rain. Precipitation over the week was only about 0.85 inch. The season long total for the region is about 25 inches. Soils are wet.

The upcoming week will be warmer with highs in the 70s. Highs should be in the 80s by the weekend. The long-term outlook for the fall is for warmer than normal conditions.

Southwest Michigan GDD summary from March 1 – Sept. 9, 2018

Station

GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMRC)

3,752

3,318

2,621

Lawton (Lawton)

3,756

3,318

2,622

Fennville (TNRC)

3,600

3,174

2,493

Average for the SW region

3,754

3,319

2,623

Accumulation last week

153

135

109

Tree fruit

San Jose scale trap catches are trailing off. We are seeing red spots on apples and peaches due to scale at sites with high scale populations. Apple maggot trap numbers are low. Brown marmorated stink bug (BMSB) adults are showing up in more sites. Hot spots with BMSB damage are reported for peach and apple orchards close to woods and soybeans. Significant BMSB aggregation for fall has not started yet. Spotted wing Drosophila (SWD) numbers remain high.

Peach and nectarine harvest has nearly ended. Varieties being harvested now include Victoria, Autumn Star and Encore. Oriental fruit moth trap catches are still significant, but are of more concern for apple and plum growers now. Remove fruit that are not harvested to reduce carryover brown rot problems for next year. Fruit mummified in the tree are hard to remove completely.

Brown marmorated stink bug damage is being found in peaches. Symptoms include white to brown regions of slightly firmer, disorganized peach flesh close to the skin. Late season peach varieties tend to be more prone to mealy flesh problems that show up in storage. Mealiness tends to show up on very firm peaches that are stored in the temperature range of 36 to 42 degrees Fahrenheit.

In cherries, serious defoliation by cherry leaf spot is very common. Most growers stopped their fungicide protection programs after Labor Day.

CLS defoliation

This tart cherry orchard has been almost completely defoliated by cherry leaf spot.

Plum harvest of Damson, Empress and other end of season varieties is underway. Brown rot and bacterial spot have been the primary concerns this season. Ripening plums should be protected against apple maggot. Apple maggot numbers have dropped to very low numbers in Trevor Nichols Research Center trap line. Codling moth and oriental fruit moth can also attack plums. SWD can attack plums as they ripen and soften.

Apple harvest of early Fuji types, Gala and Honeycrisp are underway for central Berrien County. Some growers are picking taffy apples. Apple ripening has been rapid this year. Apple maturity test reports from Michigan State University Extension are available Wednesdays from now until mid-October for the major apple growing regions in Michigan. See the Apples Maturity page.

Growers with a light crop or with bitter pit-susceptible varieties should include calcium in their cover sprays to reduce bitter pit. Where apple scab is present on fruit and leaves, consider beefing up fungicide coverage shortly before harvest to help prevent pinpoint scab showing up in storage. Reapply fungicides for sooty blotch and fly speck whenever the hours of leaf wetness exceed 250, or 2 inches of rain have occurred since the last fungicide application.

Apple scab

This apple scab lesion on a Golden Delicious apple could infect other fruit before harvest.

Oriental fruit moth is the primary internal worm problem needing protection at this time. Obliquebanded leafroller has been relatedly uncommon this season. Apple maggot catch numbers are low.

In pears, Harrow Sweet harvest will start soon. The primary insect threats now are codling moth and brown marmorated stink bug.

Small fruit

Grapes are nearing harvest. There is a large crop of grapes this season. National Grape has announced the Niagara harvest will begin on Sept. 19. They plan to harvest Niagara for about five days and then switch to Concord. They will return to Niagara harvest after Concord harvest is complete.

With all the rain this season and in the last few weeks, downy mildew on the leaves in some vineyards. Protect leaves of susceptible varieties to ripen the grapes. Botrytis and sour rot symptoms are apparent in damaged wine grape clusters.

Niagara problems

The leaf canopy on this Niagara grape vine has been killed by downy mildew. The exposed fruit clusters show black rot lesions on berries, black rot mummies and berries rotting from splits or other damage to the fruit.

Fourth generation grape berry moth is flying. Grape growers who will not harvest soon need to check vineyards and consider controls of the fourth generation. The number of SWD flies keeps increasing. We are seeing split berries, fruit rots and vinegar flies in clusters with damaged berries. Be mindful of SWD and vinegar fly infestation as harvest nears and more split berries occur.

We seeing brown marmorated stink bug (BMSB) in vineyards, but no signs of feeding. Look for this insect until harvest. For all these late season and harvest pests, insecticides with good contact activity and a short pre-harvest interval are the best option.

Blueberry harvest is over. Next year’s flower buds are forming and are visible in many fields. Soils are generally very wet and new growth is apparent in many fields. Some growers are pruning while labor is available. Many fields are very weedy and growers are planning their fall herbicide applications.

Strawberries generally look good. As the day length shortens the plants will set flower buds for next year. Day neutral strawberries are being harvested. Ripening strawberry fruit needs to be protected from SWD and growers should harvest as frequently as they can to minimize the amount of time the fruit is available to the fly.

Bramble harvest continues with fall raspberries. Raspberry are a preferred host for SWD and the fruit always needs to be protected.

Upcoming meetings

The annual Trevor Nichols Research Center Field Day is Tuesday, Sept. 25, 2018 from 1 to 4 p.m. at the Trevor Nichols Research Complex west of Fennville.

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Tags: fruit update, msu extension, southwest michigan fruit update


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