Southwest Michigan fruit regional report – July 7, 2015

Tart cherry and blueberry harvest are underway with an excellent crop expected.

Tart cherries are harvested using a mechanical truck shaker to shake fruit off trees. All photos by Mark Longstroth, MSU Extension
Tart cherries are harvested using a mechanical truck shaker to shake fruit off trees. All photos by Mark Longstroth, MSU Extension


Last week was cool with high temperatures in the low 70s, and low temperatures in the 50s. Warmer weather returned over the holiday weekend with highs reaching into the upper 80s. Last week was dry. Some scattered showers came ashore Wednesday morning, July 1. Most areas received little or no rain. Rainfall in the region for the month of June was 3 to 5 inches. Some areas received over 7 inches in June. Soils are beginning to dry, except for wet spots in fields.

Weather for the upcoming week will be a repeat of last week. The week will be cooler with a warm weekend. High temperatures will be in the 70s and lows generally below 60. Rain showers are crossing the region Tuesday, July 7, with passage of a cold front and the return of cool, dry air. With the recent cooler weather, we are a little behind normal in terms of crop development. With the pleasant weather last week, we picked up about 25.4 growing degree days (GDD) base 42, 22 GDD base 45 and 16.3 GDD base 50 per day. We expect similar heat accumulations this week.

Southwest Michigan GDD summary from Jan. 1 through July 5, 2015


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMRC)




Lawton (Lawton)




Fennville (TNRC)




Average for the region




Accumulation last week




Tree fruit

Soil moisture is adequate with good growth. Foliar diseases are common given the long wetting periods in May and June. There is a strong flight of greater peachtree borers and lesser peachtree borers. Young trees are especially vulnerable and should be treated with trunk sprays to prevent these pests. Oriental fruit moth trap catches are up, signaling the beginning of the second generation flight in many sites. Obliquebanded leafroller egg hatch is underway and adult trap catch is declining across the region.

Apricot harvest continues. Bacterial spot problems are generally minor.

Peach fruit are growing rapidly. Early peaches are starting to color and develop a red blush. First spot-pick harvests of early varieties began this week in a few early sites. Redhaven harvest is predicted for Aug. 3 in central Berrien County. See “Peach harvest dates available on MSU Enviro-weather” from Michigan State University Extension for more information.

We are past the treatment window for rusty spot. Bacterial spot symptoms are building on susceptible varieties. Mycoshield (21 day pre-harvest interval or PHI) can be used to help keep bacterial spot on foliage from spreading to fruit. Oriental fruit moth trap catches are up. There is some shoot tip flagging and fruit entries by larvae. Other direct fruit pests include tarnished plant bugs and the common stink bug, which cause pinhole punctures on fruit. Brown marmorated stink bugs (BMSB), the new pest slowly building in the area, have the potential to cause significant damage to fruit.

Sweet cherry harvest continues. Generally, fruit quality has been good. There has been some fruit cracking due to rain and associated brown rot. Bird feeding problems have decreased as more fruit ripens. Cherry leaf spot symptoms are easy to find in some orchards and growers need to maintain protectant fungicide coverage before rain events. Warm rains are good infection periods for brown rot and sweet cherries are very susceptible to brown rot as the fruit ripens.

Tart cherry harvest is well underway in southwest Michigan. Crop yields and quality are generally good to very good, with fruit size somewhat smaller where crop loads are heavy. Some soft cherries are being seen with harvests in warmer afternoons. Cherry leaf spot is a significant problem in many orchards. After harvest, most growers will switch to chlorothalonil to protect their remaining leaves. See “Controlling cherry leaf spot in orchards with existing symptoms” for more information. Tart cherries are moderately tolerant to copper, but growers need to avoid copper buildup on leaves and discontinue copper use if there is little or no rain between sprays. Use the MSU Enviro-weather forecast model for cherry leaf spot to help guide sprays and track infection periods. Powdery mildew is becoming common in many orchards. Eastern cherry fruit flies are being trapped in the region. Late-harvested cherries that are soft-ripe on the tree may be prone to infestations by cherry fruit flies and two-spotted Drosophila vinegar flies.

clamp tart cherry harvester
The business end of a cherry shaker. This clamp gently but firmly holds the trunk for two brief shakes that removes most of the fruit from a tart cherry tree.

Tart cherries tank
Tart cherries are cooled in tanks of flowing cold water after harvest.

Japanese plums are starting to develop color, with fruit drop still continuing. Plumcot Spring Satin harvest has started. Plum fruit and leaves are susceptible to bacterial leaf spot, but Mycoshield is not labeled for use on plums. Shoot growth has stopped ending treatment to reduce black knot. Ripening fruit becomes susceptible to brown rot.

Apples are sizing well and most growers have finished hand-thinning. Yellow sticky boards should be deployed to monitor for apple maggots, which should emerge after the next significant rain. Growers need to include fungicides in their next cover sprays to control sooty blotch and flyspeck. Growers should reapply fungicides whenever the hours of leaf wetness exceed 250 since the last fungicide application. Growers with a light crop or with bitter pit-susceptible varieties should include calcium in their cover sprays to reduce bitter pit.

We are still catching codling moths and first generation egglaying continues. According to the MSU Enviro-weather codling moth model, we are past peak egglaying and about a week away from second generation emergence. Growers should be scouting for obliquebanded leafroller larvae. The obliquebanded leafroller model on MSU Enviro-weather indicates we are past peak egg hatch in the region. Green aphid populations are building on succulent leaf tissue.

Pear crop potential is good. Growers are removing watersprouts from trees to discourage pear psylla populations. Pear psylla numbers are increasing.

Small fruit

Japanese beetles are out. Leaf feeding similar to Japanese beetle was reported in raspberries and several other crops, but no insects were found. This is probably the Asiatic garden beetle, which appears sporadically in southwest Michigan. This is a brown beetle similar in size to a Japanese beetle that emerges and feeds at night. A broad spectrum stomach poison such as Sevin will be effective against this pest. We are beginning to catch more spotted wing Drosophila (SWD) in southwest Michigan. Most traps have not caught any flies – most caught only single flies – but a few traps have caught one or two flies. SWD is a pest of ripening fruit and numbers should increase as wild berries ripen.

Grape berries are nearing berry touch in Concord and Niagara, and are in buckshot berries in hybrid and vinifera wine grapes. Juice grapes have grown out of their susceptibility to fruit infections of powdery mildew, and are developing resistance to downy mildew, black rot and phomopsis. Vinifera grapes remain vulnerable to all these fungi. Black rot fruit infections are developing in some vineyards.

Second generation grape berry moths are laying eggs on clusters now. Second generation egglaying was predicted to begin July 5 in Berrien County and July 6-7 in Van Buren County. At vineyards where coverage with a reduced-risk product hasn't occurred, growers will be applying a broad-spectrum insecticide during the next dry period. See “Grape berry moth model predicts start of second generation around July 4 in southwest Michigan” for more information.

In wine grapes, continue scouting for potato leafhoppers, which arrive on storms and winds from the south. Look for grape leafhoppers in juice grapes. Japanese beetles have also emerged and are causing leaf-feeding damage in some vineyards. Usually only severe outbreaks of these insects require treatment.

Blueberry hand-harvest is well underway with growers harvesting Duke and other early varieties such as Bluejay. Bluecrop harvest should start next week. Trap catches for cherry fruitworms and cranberry fruitworms are down and declining. Scouts are catching blueberry maggot flies and SWD. Ripening fruit needs to be protected from these pests. Growers should apply fungicides to protect fruit from anthracnose and alternaria fruit rots and new shoots from stem blights such as phomopsis. There have been reports of alternaria fruit rot on ripe fruit.

Strawberry growers are renovating their fields. After renovation, be sure the field has adequate moisture and irrigate if necessary. Protect newly emerging leaves against potato leafhoppers and foliar diseases of strawberries.

Raspberry harvest is underway for red and black raspberries. This year’s primocanes are about 3 feet tall and just beginning to show flower buds. Japanese beetles are out and can be a problem in raspberries. Controls should be applied as soon as you see Japanese beetles in your field. Growers need to time their controls with harvest and pay attention to the PHI on the label. Raspberries are also very attractive to SWD and growers should pay close attention to protecting against this pest. See “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers” for more information.

Raspberries primocanes 
This year’s shoots, called primocanes, are just starting to show flower buds for the fall raspberry crop.

Upcoming meetings

Be sure and register for the annual Viticulture Field Day July 29 from 9 a.m. to 6 p.m. at the Southwest Michigan Research and Extension Center, 1791 Hillandale Rd., Benton Harbor, MI 49022. Grape, winemakers and others interested in viticulture are invited to attend. This is a full day of viticulture. The event includes an outdoor trade show, equipment demonstrations and tours of the research farm. Learn more about the event and register for this annual open house focused on grape production in southwest Michigan. For more information, contact Diane Miner at

See also

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