Review of 2011 fruit season in southwest Michigan

A wet spring and dry summer created an interesting growing season for fruit in southwest Michigan this year.

The coldest temperatures of 2011 were on January 23 with lows down to -20°F reported by some growers. These temperatures occurred during an extended cold period and were recorded in low-lying areas. There was little damage to fruits growing at sites with good air drainage, where low temperatures were closer to 0°F. Significant injury was apparent in the spring in some crops. Snow covered the ground for most of the winter.

Spring got off to a quick start with warm weather in March causing many plants to start growing, but cooler weather then stopped growth. The spring was generally cool and wet, slowing plant growth. There were no major spring freezes. During the cool spring, the region fell about two weeks behind normal fruit development. Most sites received over 12 inches of rain from March 1 through May. Bloom weather was often cool and cloudy, leading to poor pollination for some crops. In the spring, soils were wet and often saturated where drainage was poor. One of the major complaints linked to the excess rainfall this spring was the premature failure of soil-applied herbicides. Weed control in many plantings was poor, indicating the loss of herbicide control probably due to excessive leaching of the active ingredients.

June was hot and dry with few significant rains. The heat and fully developed leaf canopies rapidly increased plant water use and sandy soils dried out quickly, leading to drought stress. Hot weather increased growing degree days, which caught up to the long-term average by the beginning of July. Strong storms moved through the region several times during June and July causing significant damage in some areas. At least three hail storms occurred during the summer and fall, causing losses in the region, with most damage occurring in the Hartford and Eau Claire areas. Rains in July and August generally kept up with water use, but frequently the soils dried out between rains. Warm conditions continued into late September when cool, rainy weather set up the first significant freeze of the fall on October 2, 2011.

Southwest Michigan growing degree day totals from March 1 through September 30
Location GDD 42 GDD 45 GDD 50
Bainbridge 3953 3441 2644
Fennville 3757 3259 2479

Tree fruit

The cold, wet spring allowed many diseases to become established early. Growers often reapplied fungicides after protectant materials were washed off. Cool, rainy conditions reduced pollination and fruit set for early blooming tree fruit. With the wet spring, it seemed that diseases were a bigger problem than insects. Stink bug injury was found in many fruit plantings, but the presence of brown marmorated stink bug was never confirmed this season (as of October 10, 2011) by finding live insects in fruit plantings. San Jose scale and wooly apple aphids were a continuing problem in some orchards. Oriental fruit moth was less of an issue this year for some growers.

Apricot growers had a light crop and no major problems.

In peaches, the loss of fruit buds in sites away from the Lake was a symptom of winter injury. Orchards close to Lake Michigan had abundant fruit buds. Crop potential was excellent. Peach leaf curl was more prevalent than normal for some area orchards. The cool, wet spring favored this disease and numerous wetting events probably washed off protectant controls. Applications of copper fungicides provided the poorest results for controlling peach leaf curl this year.

Copper fungicides were more commonly used this year to suppress bacterial spot. In orchards with susceptible varieties located next to vegetable fields, bacterial spot was a problem due to infection of wounds created by blowing sand. Frequent summer rains exacerbated brown rot problems on fruit. Fruit size and quality were generally very good, although dry weather held back fruit sizing at sandy sites. Fruit harvest was delayed primarily due to cool weather after bloom. Fruit skin coloring on late season varieties was poor. Spotted wing Drosophila traps set out in peach orchards caught a few adults in September after harvest, but numbers were very low.

In sweet cherries, some varieties had light fruit sets. This was probably due to wet conditions and poor pollination during bloom. Bacterial canker symptoms on the fruit (sunken black lesions) were easy to find in both sweet and tart cherries. Generally cherry fruit seemed small. This may have been the result of the cool spring that could have reduced cell division during early fruit growth.

In tart cherries, the crop was light. Bacterial canker was a problem on both fruits and leaves. Hail and wind storms just before harvest resulted in significant fruit losses and wind whip bruising to the remaining fruit. Tart cherry harvest began July 11, much later than normal.

Cherry leafspot symptoms appeared early, even for growers who thought they had a tight fungicide protection schedule. Fungicide resistance in cherry leafspot may be becoming a significant problem in southwest Michigan orchards. Many trees were completely defoliated soon after harvest.

In plums, cool and wet conditions during bloom resulted in a light crop of Japanese plums for most producers. European plums had a more normal crop with good size and quality.

Apple yields were more normal in 2011, following the poor southwest Michigan yields in 2010. Apple scab infections were common in 2011. Before bloom, frequent rains caused many growers to reapply fungicides. Scab symptoms began to appear in early May. Hot and humid summer-like conditions and thunderstorms during bloom resulted in fireblight blossom infections on May 11, 12 and 13. Fire blight was a common problem. There was a second round of fireblight infections during late bloom and strong storms during the summer spread the disease, resulting in significant infections in some orchards.

Apple ripening in early season varieties was close to the predicted apple harvest dates, but earlier than predicted for Golden Delicious, Red Delicious and Fuji. Stop-drop sprays to reduce pre-harvest fruit drop were very important in 2011 for drop-prone varieties. High winds shortly before Red and Golden Delicious harvest caused significant fruit drop, in spite of these applications.

In pears, fire blight on Bartlett was the most significant disease problem. The experimental USDA pear selection 71655-014 continues to look good in trials in area orchards. This fire blight resistant pear ripening about 10 days after Bartlett will be named shortly. Pear psylla did not seem to be as prevalent this season.

Small fruit

Spotted wing Drosophila (SWD) traps were set out during strawberry season, but no flies were detected until August. Initial numbers were low and steady. SWD populations spiked upwards in blueberries and other small fruit as insecticide applications ended after harvest and populations built in unharvested fruit. By October, very high populations of SWD were being trapped. It seems likely that there is a small and scattered population in wild small fruit and abandoned blueberries in southwest Michigan. Last year we saw a steady rise of this small vinegar fly in the fall and we saw the same pattern this year. SWD were trapped in fall raspberries, strawberries, blueberries and grapes.

In grapes early growth was slow. Snow and cold weather in late April created a developmental holding pattern until weather warmed more consistently. Hail on April 27 in the Lawton and Mattawan area caused some damage to buds. Bud break for juice grapes occurred on May 3, and in wine grapes generally a week to 10 days later. Plants had good vigor going into 2011. The fruit potential this year was excellent following spring freeze reduce crop in 2010. Full bloom for Concord was June 8, which is the 10-year average bloom date and two days earlier than National Grape’s long -term average date for Concord bloom. Temperatures above 90 caused bloom to begin and end quickly. After bloom, it was apparent we had a very heavy grape crop. Many growers thinned their fruit down to manageable levels in early July.

A brief hailstorm occurred across parts of Berrien County on August 7. Temperatures on the morning of October 2 dropped to the high 20s. Injury to leaves was most noticeable in the Bridgman and Baroda area and around Decatur and Paw Paw. So far, the quality and quantity of harvested grapes has been good.

Very little climbing cutworm or grape flea beetle damage was observed this spring. Grape berry moth was caught in pheromone traps by the week of May 16. We set biofix (50 percent of wild grape cluster with 50 percent of flowers open) for grape berry moth May 30-31 in Berrien County and June 1-2 in Van Buren County. 810 GDD base 47 after biofix marks the beginning of egglaying and the recommended timing for insecticides to control second generation grape berry moth. We passed the 810 GDD mark on July 4 at Scottdale and July 8 at Bainbridge in Berrien County, and July 7 in Lawton and July 9 at Teapot Dome in Van Buren County. Third generation grape berry moth was out by the week of August 9 and a fourth generation was out by September 7. Growers had a much better handle on grape berry moth control this year than last year. Rose chafers appeared the first week in June at sandier sites in Van Buren and Berrien counties, but generally were below economically damaging levels. Japanese beetle injury was negligible.

The wet weather in spring provided good conditions for the development of phomopsis. Symptoms began showing up on leaves and shoots at the end of May and early June. The amount of phomopsis ended up being about average by harvest time. The first symptoms of black rot infections began showing up around June 8. Growers needed to keep on top of downy mildew this year. There was favorable weather for infection periods, including frequent morning fogs in August and September. In the untreated Southwest Michigan Research and Extension Center (SWMREC) sentinel plots, downy mildew caused severe defoliation (80 to 95 percent) of Chancellor, Vignoles, Pinot Noir and Chardonnay, and 50 percent defoliation of Niagara. Concord showed lesser amounts of injury (about 20 percent). Powdery mildew began showing up in late August in susceptible wine grape varieties. The incidence of sour rots was about average.

In blueberries, winter injury was apparent by late April as plants leafed out. Empty flower buds opened prematurely, while other flower buds stopped growing after the initial bud swell. Winter injury was wide spread as dieback of the shoot tips, especially in young plants that were set out in the fall of 2010. Water was standing in many fields during the rainy spring. During this time, the root system of newly established plants did not grow significantly after planting. Hot, dry weather in June exhausted the available moisture from the small peat root balls in sandy soils, causing plants to wilt and die. The 2011 crop was very variable with many fields having a light crop. Jersey was the most affected variety, but many of the late season varieties also had light crops. Many fields had a light bud set from 2011. One possible reason for the light bud set was the hot and dry summer of 2010, which could have reduced plant vigor late in the season when bud set occurs in blueberry. Overall, most growers were disappointed by the poor yields in 2011.

Strawberry fields generally looked good this spring. Hot conditions just before harvest caused plant collapse due to black root rot in several fields. In the hot weather, the diseased root system could not supply enough water to the leaves and ripening fruit. The hot conditions hastened fruit ripening, moving harvest quickly. Because of the wet conditions this spring, slugs were a problem in some fields. Gray mold was also a problem for some growers. Tarnished plant bug injury was present, with injury levels about average. SWD was found in a high tunnel research planting of day-neutral berries at SWMREC and caused considerable damage to fruit beginning in September. Some U-pick growers remained open later than usual because the late ripening fruits were larger than the small fruit earlier in the season. After harvest, irrigated fields displayed good foliage growth.

In brambles, winter injury was visible in many sites, especially in blackberries. Cane damage to blackberries and some raspberries was common in some sites. Winter injury to raspberries and particularly blackberries was wide spread. SWD has shown that it can do well in plantings in high tunnels. It caused fruit injury and yield loss in an experimental planting of fall red raspberries at SWMREC.

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