Regional reports on Michigan fruit – August 14, 2012

MSU Extension educators’ pest and fruit updates for Michigan.

This week’s regional reports:

Southwest Michigan - Mark Longstroth, Bill Shane, and Diane Brown, Michigan State University Extension

Southwest Michigan
Southwest Michigan

Rain has recharged soil moisture and trees and shrubs are putting out new growth.


Cooler fall-like weather moved into the region last week. Temperatures fell from highs near 90 degrees F at the beginning of the week, to highs near 60 on Friday (August 3). Rainfall over the last week continued to recharge the soil with water, with rainfall totals ranging from 0.6 to 1.3 inches.

Warmer temperatures with highs around 80 degrees are forecast for the coming week. Our Growing Degree Day accumulations continue two or more weeks ahead of normal.

Southwest Michigan   Growing Degree Day Totals from January 1 through August 12, 2012


GDD 42

GDD 45

GDD 50





Trevor Nichols:




GDD since 8/5/2012




Check the MSUE Fruit page at the new MSU Extension site for more information.

Small fruit

Japanese beetle activity seems to be winding down shortly. Spotted winged drosophila (SWD) trap catches increased last week and we expect the numbers to continue to increase with cooler temperatures. We can expect a new generation every 2 or 3 weeks. This pest has been found in all ripening small fruit except grapes, which are not yet ripe.

Strawberry growth is excellent except where potato leafhoppers have stunted growth. Day neutral strawberries in the high tunnels have slowed down. Two spotted spider mites are present in moderate numbers. SWD flies have been found in the high tunnel strawberry plantings at SWMREC and larvae have been recovered from the fruit.

In brambles, blackberry and fall raspberry harvest is underway. Raspberry primocanes are growing well with the increased rainfall. Growers report spider mites, Japanese beetles and potato leafhoppers. Spider mites and spotted wing Drosophila are the primary problems in high tunnel raspberries. Spotted wing Drosophila females and males have been trapped in high tunnel plantings at SWMREC, and larvae have been found in the fruit. We continue to see redberry mite damage on blackberries and similar injury on fall red raspberries in the tunnels. This is characterized by uneven ripening of drupelets, with some turning black and others remaining red. The raspberries show uneven ripening with some drupelets remaining white.

Blueberry harvest is winding down rapidly and many growers are finished for the season. Growers are machine harvesting Elliott and other late season varieties. Spotted winged Drosophila (SWD) numbers are up and larvae have been found in the fruit on some farms, and some growers have ended their season early because of this pest. Blueberry maggot numbers are up following all the rain. Growers with ripening fruit should be controlling these pests. See the most recent Blueberry Insect Update for more information. Controls for anthracnose and alternaria fruit rots should be maintained.

In grapes, veraison continues.Japanese beetle feeding is declining. We are well into the third generation of grape berry moth and the fourth is expected near the end of August. Check the grape berry moth model at Enviroweather to check the progress of the model for your vineyard. Grape berry moth biofix was May 21 at the Bainbridge Center Enviroweather station and May 19 at the Berrien Springs location. Grape berry moth trap catches varied last week, and most infested clusters are found along vineyard borders. Grape disease pressure continues to be low. Recent rainfall and increased humidity will provide more favorable conditions for powdery mildew. Downy mildew will become a problem when we get daily heavy dews in August.

Tree fruit

With the recent rain, foliage is greening up and showing better color and shoots have resumed growth. Crawlers of the second generation of San Jose scale started emerging three weeks ago. Rain has reduced some of the stress caused by European red mite and two-spotted spider mites.

Peach foliage in some sites is still showing nitrogen deficiency symptoms in spite of recent rains, in part due to reduced fertilizer applications in this poor crop year. Fruit are showing relatively dark coloration and some bleeding into the fruit as a result of earlier warm temperatures. Rains over the last few weeks have caused skin cracking on some varieties. Varieties ripening now include PF24-007, SweetStar, and Cresthaven. PF25, PF27A, and Glowingstar will start soon.

Cladosporium scab symptoms (green/brown clustered spots) showing up on fruit now were due to infections taking place at least 30 days earlier. Flavor of peaches continue to be generally very good, although a few varieties have somewhat bitter and thick skin.

Cherry leaf spot infections, normally yellowing tops of tart cherry trees by this time of season, are still relatively light. Recent rains have been cherry leaf spot infections.

Plum trees have resumed foliage growth. Varieties being harvested now include Queen Rosa, Satsuma, and Vanier. The few surviving fruit in the area are somewhat scarred, but tasty. Now is a good time to examine new branches to see if San Jose scale of the second generation has spread.

In apples, light crop, frost scars, and recent rains have contributed to various cracks, bitter pit, followed by surface rots. Gala varieties are showing light red and stripe color development but still are relatively poorly colored and starchy throughout. Starch tests should start to watch apple maturity. Honeycrisp fruit are putting on good size, but have many skin imperfections this year—leaves of this variety have been showing mottling for several weeks. The light apple crop will make harvest go quickly, but the hot weather increases the tendency for fruit drop. NAA is applied as a stop-drop material when fruit start to drop, about two weeks or less before harvest, but not less than four days. The stop-drop chemical Retain is applied at least 28 days before harvest but not earlier than 35 days.

For apple pests, codling moth second generation flight continues to decline. Obliquebanded leafroller (OLBR) feeding on foliage is uncommon. Oriental fruit moth second generation moth flight is continuing at a low level—fruit entries by the larvae can be found. Leaf bronzing from European red mite, two-spotted mites, and rust mites is common. Apple maggot fly catch has increased with recent rainfall.

Pear fruit are about 2.75 to 3.0 inches in diameter on Harrow Sweet. Some brown leaf discoloration due to earlier red mite infections can been seen.


A hop production workshop will be held at the Southwest Michigan Research and Extension Center (SWMREC) August 21 from 9 am until 3 pm.  Contact the Berrien County Extension office for registration information call 1-269-944-4126.

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Southeast Michigan – Bob Tritten, Michigan State University Extension

Southeast Michigan
Southeast Michigan


Much needed rain finally came to many fruit farms across the region late last week, with a bit more for others overnight last night (August 13) and this morning (August 14). Rainfall totals vary a great deal over the region, from a low of 0.35 inches at Pigeon, Mich., and the tip of the Thumb, with Lapeer, Mich., and Romeo, Mich., receiving around 2 inches, and further south Petersburg, Mich., receiving just over 1 inch. The MSU Enviro-weather station at Freeland recorded a whopping 9 inches over three days. Many fruit farmers have shared with me this week that this is the nicest rain event they have had since March, with 3 to 4 inches of rain coming slowly over two to three days.

Even though we have had rain, for many fruit farms it was enough to bring only temporary relief from the prolonged drought. The effects of this drought will continue to play itself out over the next few years, with reduced fruit size for many fruit crops and lack of growth this season, and potential reduced winter hardiness of flower buds and woody tissue this winter.

For farms that received an inch of rain or less, growers need to be watchful for the resumption of signs of drought stress.

The last time we experienced drought to this extent was in 1988, and that year the rainfall finally came in early August. This year’s drought conditions are more intense than in 1988, as this season is two to three weeks ahead of normal and we have had a much hotter summer. Even with the 3 to 4 inches of rainfall we have received over the last week, we cannot make up for a dry season with one major rain event. Let’s hope that we continue to get more rainfall over the next few months.

Our early warm season is still running nearly three weeks ahead of normal in terms of growth stages, and with all of the heat of this season we are back to being more than three weeks ahead of normal in terms of degree day totals.

East Michigan Growing Degree Day Totals for March 1 to August 13





Commerce (Oakland)




Emmett (St Clair)




Flint (Genesee)




Lapeer (Lapeer)




Petersburg (Monroe)




Pigeon (Huron)




Romeo (Macomb)




Tree fruits

Apple harvest of Ginger Gold and Zestar is underway where growers have an apple crop this season. Many apple varieties are approaching 3 inches in diameter, although I am seeing a stall in fruit size increases over the last three weeks, mainly due to drought stress.

Apple maggot trap catches have finally started to be seen on red sticky ball traps in the last week, and trap catches on yellow sticky board traps continue. Potato leafhopper leaf curling continues to be very common in unsprayed blocks. Codling moth trap catch has remained very low and steady over the last six weeks. I am not sure what is going on with codling moth trap flight and trap catch this season. I had a very strong early trap catch, in fact record numbers at most farms, and then trap catches have been nonexistent for the last six weeks. I was not able to set codling moth traps in an orchard that ended up with a crop this season; maybe their emergence pattern has changed with no crop. Japanese beetle numbers have dropped again in the last week. European red mite and two-spotted spider mite populations are being kept in check by predators at most farms where there is no crop.

Powdery mildew-infected terminal branches continue to die back in unsprayed apple blocks. A few strikes of fire blight continue to be seen and I continue to see a few larger branches die due to black rot infections in the wood.

Peach harvest of late-season varieties continues and will be finishing up soon. Fruit size is being reduced from drought stress at most farms.

Sweet cherry and tart cherry leaf drop from a combination of drought stress and cherry leaf spot disease continues. Where farms have had a major rain event, another cherry leaf spot control needs to be applied.

Small fruits

Strawberry fields that were renovated are starting to look better, with increased leaf growth. Where potato leafhopper controls have been applied in new berries, plantings look much better with a great deal of runnering taking place, with most rows now filling out.

Raspberry harvest on fall bearing types from fruiting lateral canes or bud berries started at most farms a few weeks ago. This harvest is rather limited, however, and most farms are not able to open consistently. Many growers had thought that since so many of our other fruit crops began harvest two weeks early (for example strawberries and blueberries) this season that fall raspberries would be early as well. This is not the case for fall raspberries. Remember that fall red raspberries were mostly burned back to the ground from the April 29 freeze event, thus they started from scratch again at that time, making the beginning of harvest at about the same date as most years.

Most growers report that canes are 1 to 1.5 feet shorter this season. This, too, is related to drought stress. Even where raspberries have been irrigated regularly this season, I am seeing many signs of drought stress.

Spotted wing Drosophila trap catches started to be seen four weeks ago at just a few fall red raspberry farms that had trap catches last year, and in the last week I saw my first trap catch in traps that I am monitoring for the season. We found that trap catches decline a bit in hot weather, however it has increased with cooler temperatures.

Blueberry harvest will be wrapping up in the next few days at most farms as berry size has diminished due to drought stress at many farms. Growers still picking need to be concerned about monitoring traps closely for spotted wing Drosophila trap catches and the possibility of needing to control it if harvest is expected to continue more than a week or so. Blueberry maggot trap catches continue at most farms, especially where there has been a good rain event. Japanese beetle numbers have declined sharply in the last two weeks. Bird feeding has been heavy and continues at most farms.

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Grand Rapids Area Small Fruit– Carlos García-Salazar, Michigan State University Extension

Grand Rapids Area
Grand Rapids Area

Small fruit production in the Grand Rapids region is well underway with most of the main small fruit crops harvested or in the process of being harvested. Climatic conditions occurring during the present season accelerated the growth and development of all crops advancing their harvest time almost a month in relation to their normal harvest time. Currently, weather conditions in the region have improved in comparison with previous weeks. Daily maximum temperatures have come down from the upper 90s to the 80s. On average, maximum temperatures in the area are 82 F and the minimum temperatures are 58 F.

There were some thunderstorms in the area during the past seven days that allowed for an accumulation of 2.20 inches of rain, although in some areas rain accumulation reached more than 2 inches. For some crops, this rain came too late to improve their condition, but it helped to maintain the health of crops in blueberry fields being harvested. In some fields, there were already symptoms of fruit dehydration, especially in fields located in sandy soils, despite extensive use of irrigation. However, rains benefited fall raspberries that are in full bloom with some fields already in the fruit set stage.

Currently, fall raspberry fields with good irrigation are progressing very rapidly and growers north of Allegan County estimate that raspberries will start ripening in the next 10 days, much earlier than in 2011. Among the problems observed are Japanese beetles and rose chafers. Japanese beetles are more of a problem in irrigated fields than in fields with no or limited irrigation. Rose chafers, on the other hand, occurred north of Ottawa County in sandy soils. However, unlike Japanese beetles, rose chafers are not a widespread problem.

A potential pest problem for fall raspberries and blackberries is spotted wing Drosophila (SWD), especially in fields that had summer varieties. Fruit leftovers from the summer crop are a perfect place for the reproduction of SWD. Currently, we are observing a rise in the number of SWD trapped in fields where plants are still having ripe fruit attached. Left untreated, SWD populations harbored in those plants will spread to the new crop as soon as the berries start ripening. It is important to spray those fields with insecticides or remove the remnants of the crop to prevent major SWD problems.

Regarding day-neutral strawberries, the fruit being harvested is of very good quality, flavor and color. Well-irrigated fields are having fruit of excellent quality. No major problems have been observed in strawberries. However, growers need to be alert to the presence of SWD in their fields. So far, SWD has been found in strawberry fields at the Southwest Michigan Research and Extension Center (SWMREC) and in Mecosta County.

So far, blueberry harvest is almost finished in the southern part of the state with blueberry fields north of Allegan County still in the process of harvesting Elliott, Liberty and other late season varieties. Currently, there are only a handful of laborers available for hand-harvesting and growers are resorting to mechanical harvest to complete the 2012 season. Problems affecting blueberries at this time are related to birds, Japanese beetles and spotted wing Drosophila.

Because spring frosts eliminated almost 90 percent of all cherries, apples, peaches and other sources of food traditionally available for birds, blueberries and other small crops are being swamped with flocks of hungry birds. This season has been tough for some growers that are in the direct path of migratory birds, especially if the fields are located near roosting sites. There were some trials with bird repellants, but results are mixed with some growers reporting good results and others not so sure about the effects of these products.

On the other hand, Japanese beetles are less of a problem in blueberry fields with limited irrigation or with drip irrigation. Drought conditions throughout the region have reduced the availability of green grass and soil moisture that favor Japanese beetle reproduction and survival of eggs and larvae. In addition, large flocks of birds present in blueberry fields are helping to clean these unwanted guests.

Spotted wing Drosophila is a different issue. The unusual mild winter and early spring brought SWD early into most small fruit fields, including blueberries. Currently, we are observing higher populations in most fields that had SWD problems in 2011. Also, in southwest Michigan in fields already harvested, the populations of SWD are increasing dramatically. Uncontrolled, this after harvest SWD buildup may create problems for the 2013 blueberry season, especially if the winter conditions are similar to the past winter. Presently, the MSU Extension Small Fruit Team is working on pest control alternatives to reduce SWD populations after harvest.

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