Regional reports on Michigan fruit – September 20, 2011

MSU Extension educators’ pest and fruit updates for Michigan.

This week’s regional reports:

Southeast Michigan – Bob Tritten, Michigan State University Extension

Southeast Michigan
Southeast Michigan

Our 2011 growing season is still running ahead of normal by almost a week. However, when I look at the beginning of harvest at some of our apple varieties, I think that we are just about on track to be a “normal” timing. Most areas of the region have received moderate amounts of rainfall over the last two weeks, with about 0.5 to 0.75 inches filling most fruit farm’s rain gauges. Soil moisture is still below adequate at most farms across the region, with the exception of the lower tier of counties where more rainfall has occurred over the last month. This concerns me a bit as I don’t like to see us move into fall with less than adequate soil moisture.

Summary of the season’s weather

The winter of 2011 was rather mild, with a lot of snow cover and adequate moisture supplies. The best way to describe our 2011 weather this spring and summer was that there were wild swings of running from too much moisture and cold temperatures in springtime to hot and dry conditions in the summer. I am not certain how the record books will look at this season, but from the perspective of eight months into the growing season the extremes of the spring and summer will even or cancel themselves out to a point where things will be fairly normal or a least in the normal range.

Our spring started out a week to 10 days behind normal when I look at degree day totals and beginning of harvest of our early summer fruit crops. The best way to describe our spring weather was that it was more autumn-like. In mid-May we started to push ahead in terms of heat, and that’s about when the rain started. From mid-May until early June was a very wet time period. For the most part, we did not have any spring frost and freeze issues to deal with. Strawberry growers only fired up irrigation systems for frost control about two to four times, but a few of these were close and not actual frost or freeze events. For apple growers, this coincided with the primary apple scab season, which was long and fierce (more details later in the report).

By the end of May, our soils were watered-logged and tree fruit growers were cutting into the orchard sod as they were doing their frequent spraying operations. By early June, we began to catch up in terms of our degree day totals. It was into the second or third week of June when rainfall began to diminish. By early July, we received so little rainfall that our soils were beginning to dry out and growers were quickly firing up irrigation systems.

Overall, growers have devoted a fair amount of time and energy to irrigation of fruit crops throughout the season. By early July, we had caught up in terms of degree day totals to a point where we were almost a week ahead of normal. We stayed a week ahead of normal for most of the rest of the growing season.

East Michigan growing degree day totals for March 1 to September 19 , 2011





Commerce (Oakland)




Emmett (St Clair)




Flint (Genesee)




Lapeer (Lapeer)




Petersburg (Monroe)




Pigeon (Huron)




Romeo (Macomb)




Tree fruits

Apple harvest continues across the region. Most growers have now finished Gala and McIntosh. Growers are going back to finish up with Retain-treated Gala. Honeycrisp harvest is also taking place. There are a number of farms where the pack out on Honeycrisp is decreased dramatically this year due to black rot infected fruit, sunburned fruit that eventually developed cracking, and in the last two weeks cracking of the skin or cuticle. Jonathon, Jonagold and Empire are the next varieties that are approaching maturity fairly quickly. Apple growers are seeing more damage at harvest from codling moth than what they are accustomed to seeing. There is also more apple scab showing up in apple bins than growers are used to seeing and on leaves in the orchard. Lastly, some varieties have a fair amount of black rot. This has been an increasing problem for several farms over the last three seasons. Varieties that seem to be most affected include Gala and Honeycrisp.

The 2010 apple crop was very light across the region, one of the shortest crops that many growers can remember in recent history. So, growers had great expectations for the 2011 apple crop. Rain brought extreme pressure to control apple scab during primary apple scab season. Some farms had 15 to 20 wetting events in the primary apple scab season this year, which is typically unheard of to have this number of wetting events, and the majority of those events ended up turning into infection period. Many growers modified their apple scab control programs to reduce the possibility of apple scab resistance developing at their farms. Most apple blocks had a tremendous amount of bloom this year, growers were very concerned about the need for thinning, and it ended up a fair amount of thinner was used. There was a great deal of natural fruit drop through mid- to late June and the crop thinned out to a point where most growers who are now harvesting are picking short, around 60 to 80 percent of a normal crop. Growers applied three to four fire blight control sprays during the blossom time. With the exception of some problem blocks, very little fire blight was seen this summer.

Overall insect pressure was light this season, with the exception of codling moth. While we did have very predictable and normal peaks and valleys of the first and second generation A and B peaks, several blocks had very high numbers of codling moth in traps. As growers are harvesting fruit, they are finding a higher than normal amount of codling moth-infected fruit. No brown marmorated stink bug was found in apples – we had been scouting for it the entire season.

Pears are harvested for the most part. Many growers had an excellent pear crop this year, one of the best that they have had in the last five years. Pear psylla continues to be an ongoing issue at some farms. This is particularly true where suckers are not removed on a timely basis.

Peach harvest was fast and furious this year, with growers finishing marketing peaches in the last week or so. For the most part, growers had a good crop of peaches this year. The exception would be where drought reduced fruit size or where thinning was not adequate. Bacterial spot control has been a major challenge for peach growers in 2011. This has been an increasing problem every year for the last three years.

Sweet and tart cherry bloom was excellent this year. However, there was a fair amount of fruit drop that occurred all the way through to harvest time that reduced the size of crop dramatically. It ended up that cherry harvest was about five days ahead of normal at most farms. While we had a quick bloom in sweet cherries, the harvest season was long at many farms. Cherry leafspot was extensive this summer in most blocks of cherries. Many blocks that did not have enough fungicide applied prior to harvest time have lost their foliage completely. I am concerned about the potential for winter injury in these trees.

Plums have been harvested for the year. Most growers had an excellent crop of Japanese plums and a normal to heavy crop of Stanley plums. Some increasing pressure from black knot has been seen this season.

Small fruit

Strawberry bloom was late this year, therefore harvest began late. The harvest season was short at most farms, with about a 15-to 19-day harvest window. Early in the strawberry harvest season it was hard to keep up with demand, and then we received a fair amount of heat and supply out-stripped demand for the remainder of the season. Slugs were a serious issue throughout the harvest window at many farms. Post-harvest insect and disease problems included potato leafhopper burn and powdery mildew damage.

Raspberry harvest continues for fall red raspberries. Most growers are now well beyond the peak of production for fall raspberries. Summer red raspberry harvest was reduced due to a combination of winter kill and cane diseases that caused canes to collapse throughout the season. Also, because of heat during the summer, the summer red, purple and black raspberry harvest was shorted. Potato leafhopper burn was also an issue in many fall red raspberry plantings. Japanese beetles continue to be an issue at many farms around the region. We have growers in the region who have not had Japanese beetles in the past and saw them for the first time in 2011, and other growers that have had Japanese beetles for the last 10 to 15 years say that Japanese beetles were not as bad as other years.

Blueberry harvest is complete for the year. Yield was short for many farms across the region, with most farms saying that they picked around 50 to 70 percent of a normal crop. Blueberries had a good amount of bloom and had a fair amount of fruit drop between bloom and harvest time. I will make the same comments about Japanese beetles in blueberries as I did in the raspberry section.

Grape harvest has taken place for many of the Concord types and growers are now waiting for the French hybrids to gain higher brix levels and for the acidity to adjust. I have already commented on Japanese beetles in raspberries, and the same holds true for grapes this year. Some growers have extensive amount of leaf drop due to powdery mildew-infected foliage, and at a limited number of farms downy mildew was an issue this season.

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Grand Rapids Area Tree Fruit– Amy Irish Brown and Phil Schwallier, Michigan State University Extension

Grand Rapids Area
Grand Rapids Area

Weather and crop summary

2011 was another rollercoaster year when it came to the weather (aren’t they all?). As a reference, in 2010, first green for Macs was on March 23. Normal first green for Macs in the Grand Rapids area is around April 10-15. In 2011, first green on Macs was on April 12. Cooler weather was the norm for the end of April into May and degree accumulations were holding at 7 to 10 days behind normal averages. Once June arrived, some 90-degree highs and 75-degree lows really pushed degree days back to more normal levels. July brought continued hot temperatures that broke records in the Grand Rapids area and pushed degree day accumulations even farther ahead of normal averages. By the end of August, degree day accumulations were totaling about 7 to 10 days ahead of normal averages.

There were only minor frost events in 2011. Fruit set was very good across all species in the Grand Rapids area. Thinning apples was a challenge in 2011. Early fruitlet drop and very high temperatures made thinning more stressful that usual. In the end, fruit set was very good, but not quite excellent across all varieties.

There were at least three separate weather events that brought either high winds or hail or both to various areas on the Ridge. Overall, it is estimated that a third of the acreage on the Ridge was affected in some way by hail. Some areas were severely affected where others only had light damage.

Rainfall totals were higher than normal for the summer of 2011. Once we got into July, the rain seemed to come in 2- to 5-inch bursts every three to four weeks. Rain in mid- to late August actually contributed to some late season shoot growth in apples at a time when terminal bud set should be taking place. There is an unusual amount of new late season growth this year. Hopefully this won’t be susceptible to early cold snaps in November and December.

Disease problems

Depending on the site, there were 17 to 19 wetting periods during primary scab season, with 7 to 13 of these being apple scab infections. This was similar in number to 2010, but very much more than an average year. There were between 7 and 10 inches of rainfall recorded at the four different Enviro-weather stations in the general Grand Rapids area. All this wet weather, combined with a higher inoculum level coming into 2011, led to some problems keeping primary scab out of apple blocks. It was a difficult year to stay ahead of apple scab with protectant fungicides as our primary active ingredients. Many growers were disappointed to see scab show up after all the spraying they did to try to prevent it. Below is a summary table of wetting events, infection periods and rainfall totals for the Grand Rapids area Enviro-weather stations.

Weather Station

# of rain events during primary scab season

# of apple scab infection events during primary scab season

Rainfall total during primary scab season (inches)









Kent City








After a mostly cool spring, the temperatures went into the 80s during bloom, giving us a high risk for fire blight infections. Preventative sprays were needed for at least two different blossom blight infections. There were wind and hail events that caused some significant trauma infections in some blocks, but overall, there was very little fire blight symptoms in 2011 in the Grand Rapids area. The use of Apogee for shoot growth control has significantly reduced the amount of fire blight we’ve had in the last three years. There was a section 18 again for Kasumin use this year and those that used it reported favorable results.

Powdery mildew seemed to be more prevalent in susceptible apple varieties in 2011, but overall, not quite as bad as in 2010. The weather was cooler early in 2011 as opposed to very hot and humid in 2010, which most likely slowed mildew growth overall. Once it turned hot in July, any mildew that did get established took off in a few blocks.

Brown rot in sweet cherry was again very prevalent and somewhat of an issue in other stone fruits. In sweet cherry, brown rot was prevalent due to the many rain events and was worse in varieties susceptible to bacterial spot on the fruit.

Insect pests

With the cold start to 2011, insect pests were slow to get moving. And, typical of a wet season, insect numbers and damage were lower than normal as well. After some higher than expected codling moth trap catches in 2010, it was good to see that this was not the trend in 2011. There were a few hot spots for higher numbers of codling moth, but overall, numbers were on the low side for 2011.

Obliquebanded leafroller numbers continued to be on the upswing in 2011, just as they were in 2010. Growers were encouraged to do more extensive monitoring with traps in 2011 for obliquebanded leafrollers and timing of sprays was more accurate. The majority of apple acreage had little problems from obliquebanded leafroller feeding, but there were a few hot spots that will need to be monitored early in 2012.

Everyone is on the lookout for the brown marmorated stinkbug and several mimics have been found, but no positive identifications yet. Growers and scouts are encouraged to be on the lookout for suspect fruit damage as orchards are being harvested.

Weed pests

Weed control is not usually a difficult task compared to everything else tree fruit producers have to deal with. It should be noted that in 2011, however, weed control was less than ideal for many orchardists. This is due most likely to the heavy rainfall totals and high heat that made it harder for herbicides to do their job. There are good fall herbicide options and 2011 would be a good year to consider them.

Apple maturity

2011 harvest dates are running very close to the normal average. Our apple maturity testing is showing an unusually higher level of early ethylene than expected. Physiological disorders are less common due to the decent crop load. Overall, fruit color and size is good to excellent. So far, apple quality is very high and prices are reflecting excellent demand. Growers are reporting picking out near to where they expected or slightly higher in some blocks.

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Northwest Michigan - Nikki Rothwell, Erin Lizotte and Duke Elsner, Michigan State University Extension

Northwest Michigan
Northwest Michigan

Weather report

As with most of the state, spring started off wet and cold in the north. In May, we had only accumulated about 218 GDD base 50 and 403 GDD base 42 since January 1. We also had ample rainfall in May and the good news was that temperatures were often too cool to trigger infection periods for the different diseases. June was also cool and rainy, but by July, temperatures turned hot and dry. In July, the Northwest Michigan Horticultural Research Station (NWMHRS) only recorded around 0.5 inches of rainfall. Most daytime temperatures in July were in the mid-80s and we also had a few days where we reached into the 90s.

August was also hot and dry, but we did have 1.5 inches of rain, which was spread over more days during this month. Overall, the NWMHRS accumulated 3448 GDD base 42 and 2296 GDD base 50. During the 2010 season, we accumulated 385 more growing degree days base 42 and 239 GDD base 50. Compared to our 21-year average, the 2011 season had 8.4 more GDD base 42 and 50.5GDD base 50 – in the end, the 2011 season was fairly comparable to “normal.”

Crop report

The strawberry crop started out the season in the northwest pretty strong despite the early season wet weather. Strawberry harvest and quality was good, although some varieties were slightly smaller than expected. Tart and sweet cherry harvest also produced high quality fruit, which was not anticipated because of the extremely hot weather during the harvest period. Sweet cherry yields were good, albeit smaller than expected. However, the hot and dry weather later in the season prevented a devastating loss due to American brown rot issues. No soft fruit was reported in tart cherries, and again the hot weather helped growers stay ahead of cherry leafspot infections.

We had no frost events in the spring of 2011; many growers anticipated a larger harvest. When all reports were in, we harvested 92.5 million pounds of tart cherries, but theUSDA estimated we would harvest 135 million pounds. We conclude that the smaller crop size was due to pollination issues, cold and wet weather, during bloom.

Peach harvest was good, although size of fruit was small with little rainfall late in the season. Lastly, we are off to a good start in apple harvest, and thus far, only earlier varieties have been harvested: Paula Reds and Gingergolds. We expect to ramp up apple harvest next week.

Pest summary for northwest Michigan 2011

Cherries. It was a challenging season for cherry producers this year, particularly with the wet, early season. Spring weather was favorable for bacterial canker and infections were seen on sweet and tart cherry leaves as well as fruit. Tart and sweet cherry leaves that had bacterial canker infections early caused some defoliation throughout the summer. We also saw early defoliation from cherry leafspot, another disease that got an early foothold this spring. The second and third weeks in May were very rainy and growers were challenged to keep foliage covered to prevent cherry leafspot infection. We suspect growers had fungicide wash-off with the prolonged wetting period early in the season, and it was difficult to get back into the orchard to reapply fungicide applications with the continuous rain. This scenario resulted in cherry leafspot infections in May, and some blocks with severe infection dropped leaves in early to mid-July. The cherry leaf spot model predicted significant infections the third week in May, mid- to late June, mid-July, and early August.

Cherry yellows and green ring mottle virus also made an appearance this season. Growers also saw defoliation from apparent phytotoxicity issues, perhaps due to slow drying times and high temperatures. Bacterial canker infection on fruit and hail damage created early American brown rot infections that growers battled all season long. European brown rot was prevalent in Balatons and observed in Montmorency. Powdery mildew infections were moderate with most infections occurring on terminals and vigorously growing shoots. Despite intense early season disease pressure, many growers harvested a high quality crop and kept leaves on the tree well into September. We hypothesize that the hot, dry weather abated much of the disease concerns from earlier in the season.

Obliquebanded leafrollers began emerging as larvae in late May with our first adult moth trap catch recorded on June 20; moths have been caught every week since with peak flights recorded on June 27 and August 29. Many area growers transitioned away from organophosphates this season as these chemistries have become ineffective obliquebanded leafroller materials due to resistance. Obliquebanded leafroller history in apple production tells us it may take one or two seasons before populations can be brought under control with the new lepidopteron materials. Unfortunately again this season, there were isolated incidents of obliquebanded leafrollers as a contaminate issue in tanks at harvest.

The borer complex in cherries also had a protracted emergence period this season. American plum borer emergence began on May 23 and continued the entire season with positive trap catches into September. Peak emergence of the two American plum borer generations occurred on May 31 and August 1. Lesser peachtree borer began emerging in early June, peaked in late July and continued emerging at a slow pace into fall. Greater peachtree borer emergence began on June 27, peaked around August 1 and continued into the fall.

Cherry fruit fly numbers were quite high this season, and emergence began the first week in July and peaked with 330 flies captured in six traps on August1; emergence concluded by the end of August. Black cherry fruit fly populations were smaller and had a shorter emergence period from June 27 through August 16. Plum curculio populations were certainly active this season with activity detected on May 16 and stings visible as soon as fruit was out of the shuck. Even after fruit was harvested, feeding activity continued in area orchards with pyramid traps still catching weevils on August 29. Two-spotted spider mites were detected in mid-July and pressure was very high in some area orchards going into fall with the hot and dry weather.

Winter injury was also observed around northwest Michigan this spring.

Apples. With the rainfall in June, the primary scab infection period was protracted and challenging. Despite these challenges, growers managed scab well this season with only isolated problems on highly susceptible varieties or in blocks that had high inoculum levels. Fire blight was a frequent concern this spring with multiple streptomycin applications being utilized and the epiphytic infection potential reaching levels of over 300, illustrating the extreme risk of infection. Despite the intense pressure, few fire blight infections occurred and growers pruned out strikes as the weather dried up this summer. Powdery mildew infection was minimal this season.

Spotted tentiform leafminer numbers were substantial with a high trap catch of 960 on May 23 and emergence running from May 9 to August 8. Codling moth emergence began on May 23 with first generation peak emergence the second week of June. There was no clear delineation between first and second generation with emergence continuing into early September, a phenomenon common in the north. Growers did report some issues in controlling codling moth populations this season.

Obliquebanded leafroller larvae were observed in late May with adult flight recorded on June 20 and peak emergence occurring one week later. Low levels of obliquebanded leafroller emergence have continued into the fall. Apple maggot numbers remained low this year with just nine trapped the entire season. Apple maggot emergence began August 1 and continued sporadically into September. Plum curculio were conspicuously absent from the apple orchards scouted in the north, and minimal egg laying scars were reported by area scouts. Mite and aphid levels were moderate this season.

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