Southwest Michigan fruit regional report – August 12, 2014

Soils are very dry in southwest Michigan and spotted wing Drosophila numbers are up sharply.

Ripe raspberries are attractive to SWD. Photo by Mark Longstroth, MSU Extension
Ripe raspberries are attractive to SWD. Photo by Mark Longstroth, MSU Extension


Last week was warm and dry. Storms moved across the region last Monday and Tuesday, Aug. 4-5, and brought some rain to most sites. Rainfall totals from these storms varied from 0.2 to 0.7 inches. High temperatures were in the 80s and lows in the 50s. Scattered light showers moved across the region Monday, Aug. 11 and left about 0.33 inches of rain or less at most sites.

Soils are very dry. Field crops are wilting in the fields on sandy soils and stress is easy to see in some trees with yellowing and wilting leaves. Evapotranspiration (ET) for the last two weeks has been about 2 inches of water. Our sandy soils only hold about an inch of water per foot of soil.

The coming week will be warmer with highs near 80 and lows near 60. There is a chance of rain Tuesday, Aug. 12, but the rest of the week will be dry. Last week we picked up about 195 growing degree days (GDD) base 42, about 28 per day, and 158 GDD base 50, about 22.6 a day. We continue to lag about one to two weeks behind normal in GDDs.

Southwest Michigan GDD summary from Jan. 1 through Aug.10, 2014


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)




Average for the region




Tree fruit

Marmorated stink bug trap catches remain very low in southern Berrien County. Oriental fruit moth trap catches for the second generation continues to be low. The Trevor Nichols Research Center (TNRC) catches of San Jose scale males jumped up again this week. With a July 21 biofix for the second generation, the GDD base 51 F on Aug. 11 for Fennville, Michigan is 342. Crawlers are expected about 500 GDD base 51 F after the biofix, or approximately Aug. 20 for the Fennville, Michigan area. Codling moth trap catch of the second generation continues to be low for most sites. Japanese beetle adults are still active and potato leafhopper damage can be found in many sites. Now is the time to do tissue sampling for nutrient analysis.

Peach varieties being harvested in the region include Saturn, Red Haven, John Boy, Starfire and PF Lucky 13. Pre-harvest drop is being seen for some varieties. As usual, maturity is delayed on sites with heavier soils and larger crops. Brown rot is spreading in fruit clusters. Larvae from the second generation flight of oriental fruit moth traps are starting to show up in unprotected fruit. Appearance of new bacterial spot infections has slowed. Peach scab is becoming easier to find on fruit of susceptible varieties under minimal spray programs.

Cherry leaf loss due to cherry leaf spot is spreading in most orchards. Michigan State University Extension recommends growers continue protection against cherry leaf spot to maintain good healthy foliage into the fall. Chlorothalonil (Bravo, Chloronil) can be used post-harvest with a maximum of 15.4 pounds of active ingredient per acre per year.

Plum harvest of Redheart, Vanette and Castleton is underway in the region. Apple maggots, obliquebanded leafrollers, codling moths, and brown rot can be problems in plums in August. Appearance of new bacterial spot symptoms has slowed.

Apple harvest of Pristine and Zestar has begun. Growers should check the dates for applying Retain for stop drop control for the apple varieties they grow. Apples seem to be developing and maturing faster than we expected. The actual harvest dates may be before the predicted apple harvest dates issued earlier and closer to the average harvest dates in your region. Make sure you do not miss the application window – 30 days or less.

Sooty blotch and fly speck can be found on unprotected fruit. Obliquebanded leafroller trap catches are still low. Apple maggot adult trap catches continues at TNRC near Fennville, Michigan. Flight usually tapers off by late August.

Pear harvest of Bartlett in the area will start in about 10 days. Fruit are sizing well. Larvae of codling moths are showing up in fruit. Fabraea leaf and fruit spot is becoming easier to find.

Small fruit

Spotted wing Drosophila (SWD) numbers rose sharply last week in our traps. Most of these traps are located in fence rows next to fruit plantings. The SWD population increases rapidly in August. We trapped a large number of males and fewer females in our traps. More information is available on the MSU Spotted Wing Drosophila website.

Grape growers need to be aware that the third generation egglaying for grape berry moth is predicted to begin this week in Berrien County and early next week in Van Buren County. The ideal spray timing for this pest is several days after egglaying begins.

Growers have applied sprays to control downy mildew and powdery mildew. 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 MSU Extension. Additional fungicide sprays may be warranted as veraison approaches.

Southwest Michigan GDD grape summary from April 1 to Aug. 10, 2014


GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)


Average for the region


Blueberry machine-harvest of Jersey continues. Hand-harvest of Elliott has begun. Fruit quality has been excellent. The window for tissue sampling for nutrient analysis is ending. With the dry conditions, growers are irrigating blueberry fields.

SWD trap catch numbers rose sharply last week. Border sprays may be an effective way to slow the spread of SWD into commercial berry fields. Many growers have maintained tight coverage against this pest since the first catch reports last month. Growers are reminded that MSU Extension recommends shortening harvest intervals to reduce the amount of time ripe fruit is available to SWD. Harvested fruit should be chilled quickly after harvest to reduce post-harvest problems. See “SWD Management Recommendations for Michigan Blueberry Growers” for more information.

Strawberry growers need to protect against potato leafhoppers, which stunts plant growth. Day-neutral plantings are starting to produce fruit. Growers need to protect this fruit from SWD.

In brambles, harvest of fall red raspberries is underway. Raspberries seem to be the favorite fruit for SWD and we have received calls from small and backyard growers about soft berries. Growers need to apply controls as soon as there is ripening fruit in the field. Generally, control of this pest has been much better than in previous years. See “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers” for more information.

Soft raspberries and pink-stained fruit receptacles indicate a SWD infection. Photo by Diane Brown, MSU Extension

USDA funds for 2012 crop loss

Remember that USDA funds are now available to help compensate fruit growers with the 2012 crop loss and last week we were told by several fruit growers that this applies to crop losses for this season as well. The Noninsured Crop Disaster Assistance Program (NAP) provides assistance for losses to tree fruit crops due to frost or freeze. Enrolment began two weeks ago and the deadline to submit applications to Farm Service Agency (FSA) county offices is Sept. 22, 2014.

For more information about the program, visit or contact your FSA county office. You should also contact your FSA county office to schedule an appointment.

Did you find this article useful?