Southwest Michigan fruit regional report – September 2, 2014

Summer fruit harvest is ending and the focus is shifting to apples and grapes. Pests are preparing for the end of the season.

Runners and daughter plants are clearly visible in strawberry fields that were planted this spring. Photo by Mark Longstroth, MSU Extension

Runners and daughter plants are clearly visible in strawberry fields that were planted this spring. Photo by Mark Longstroth, MSU Extension


Weather during Aug. 17-31, 2014  was warm and humid. Showers and storms on Tuesday, Aug. 26, and Saturday, Aug 30, brought rain to most sites. Rainfall totals for most sites was about an inch and varied from 0.5 to 2.5 inches. A cold front crossed the region Monday, Labor Day, and dropped 0.75 inches or less of rain. High temperatures last week continued in the 80s with lows in the 60s.

The increased rain and reduced evaporative demand have eased drought stress and row middles have greened up with good growth. July and the beginning of August were very dry, but the last two weeks have had adequate rainfall to recharge the soil in many sites. Evapotranspiration (ET) for the last week averaged about 0.1 inches a day. ET for the next week should be around 0.15 inches a day or about 1 inch of water for the week.

Last week we picked up about 198 growing degree days (GDD) base 42, about 28 per day, and 142 GDD base 50, about 20 a day. We continue to lag about two weeks behind normal in GDD accumulations. Harvest timing is not as delayed, but many insect populations are running late and the short day length now means that there is little chance of extra pest generations this cool year as larvae develop overwintering forms.

Weather for the upcoming week is forecast to be cooler early in the week with a short period of hot and humid weather, and rain late in the week. It will be cooler through the weekend into the following week. The forecast for the beginning of the month was for increased rain and normal temperatures.

Southwest Michigan GDD summary from Jan. 1 through Aug. 31, 2014


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)




Average for the region




Tree fruit

We should be seeing the end of third generation of oriental fruit moth soon, but trap catches for oriental fruit moth has been generally low. Codling moth trap catch continues for some sites. We should be nearing the end of the second generation for codling moth, but some sites are still catching high numbers. The Trevor Nichols Research Center (TNRC) catch of San Jose scale (SJS) males remains high for the fifth week. San Jose scale crawlers should be active. These crawlers can settle on fruit and leave red marks on light-colored fruit. Potato leafhopper damage can be found in many sites. Obliquebanded leafroller trap catch numbers have increased over the past week.

Peach varieties being harvested in the region include Glowingstar, Fayette, PF28-007 and soon Autumnstar. Peach harvest winds down quickly in August as the fruit market moves to apples.

Many tart cherry orchards have lost most of their leaves.

Plum harvest of NY9, Bluefre, Damson and Italian are underway in some local orchards. Apple maggots, obliquebanded leafrollers, codling moths and brown rot can be problems in plums in August.

Apple harvest of early varieties has ended and growers are looking to move into the main harvest. Apples seem to be developing and maturing faster than we expected. Fruit color and size are excellent. The actual harvest dates may be before the predicted apple harvest dates issued earlier and closer to the average harvest dates in our region. There is harvest of processing apples for slices and taffy apples. Tests of apple maturity at the Southwest Michigan Research and Extension Center (SWMREC) show McIntosh firmness at 17 to 19 pounds and an internal starch conversion of 3 last week. Target firmness for McIntosh destined for longer storage is 16 pounds and 5 for starch conversion. Fruit for local sales can wait for better color and sugar content. The first hint of Gala starch conversion began last week. See “Checking apple maturity: What to look for” for more information.

Oriental fruit moth and codling moth flight continues for some sites. Obliquebanded leafroller trap catches continue to increase. Apple maggot flies are also being trapped. This flight usually tapers off by late August. European red mites have been a problem for some growers. See “Managing mites in apples” for more information. Sooty blotch and fly speck can be found on unprotected fruit.

Pear harvest of Harrow Sweet is coming up, approximately two to three weeks after Bartlett harvest. Larvae of codling moth are showing up in fruit and obliquebanded leafroller larvae are also active. Fabraea leaf and fruit spot is becoming easier to find.

Small fruit

Spotted wing Drosophila (SWD) numbers remain at moderate levels. SWD were caught in all our traps with numbers similar to last week. Susceptible small fruit should be protected from this pest. Control of this pest has been much better than in previous years. More information is available on the MSU Spotted Wing Drosophila website.

Concord juice grapes have colored. Egglaying for the third generation of grape berry moth is underway and most growers have sprayed once for this pest. There is little chance of a fourth generation of grape berry moth in southwest Michigan this year.

Growers should protect against downy mildew and powdery mildew, which are common this year. Weather conditions for the rest of the growing season with heavy dews every morning are ideal for the spread of downy mildew and growers should make every effort to get in front of this disease. See “Weather is ideal for downy mildew on grapes at this time” for background on the disease and controls recommended by Michigan State University Extension. With ripening fruit and wet conditions, wine grape growers need to protect against Botrytis bunch rot.

Southwest Michigan GDD summary for grapes from April 1 to August 24, 2014


GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)


Average for the region


Blueberry harvest is beginning to wind down. Harvest is now focused on Elliott and other late-season varieties. Next year’s flower buds are appearing near shoot tips that are not actively growing. Growing shoot tips will not set fruit buds this year. Irrigation after harvest helps maintain plant health and increase flower bud set for next year.

Weakened canes should be removed at pruning time. Growers should assess their plants to determine how much and where to prune. Some damaged canes have vigorous shoots growing from the cane above the crown.

SWD trap catch numbers in blueberries have been lower this year, but this pest is wide spread and growers who plan to continue harvest need to maintain protection. See “SWD Management Recommendations for Michigan Blueberry” for more information. Growers are reminded that MSU Extension recommends fruit should be chilled quickly after harvest to reduce post-harvest problems.

Blueberry harvester
After multiple hand-pickings for the fresh market, this blueberry harvester makes a last pass to clean up the remaining fruit in the field. Most machine-harvested fruit goes to the processing plant. Photo by Mark Longstroth, MSU Extension

Strawberry plants are runnering well in new and renovated fields. Growers need to protect against potato leafhoppers which stunt plant growth. Day-neutral plantings are producing fruit. Growers need to protect this fruit from SWD.

In brambles, harvest of fall red raspberries and fall bearing blackberries is underway. Brambles seem to be the favorite host for SWD. Growers need to maintain control as there is ripening fruit in the field. See “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers” for more information.

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