West central Michigan small fruit update – Sept. 5, 2017

While blueberry harvest is ending in southwest Michigan, a limited amount of hand and machine harvesting continues in west central Michigan.

As of Sept. 5, 2017, west central Michigan remained under weather conditions characterized by temperatures in the low 70s with occasional drizzle and light rains. For the past seven days, the daily average minimum temperature was 51 degrees Fahrenheit with an average maximum of 74 F. Precipitation accumulation over the same period was less than 0.1 inch. Lack of substantial rain during the past days triggered the need for supplemental irrigation, especially in blueberries that are in the last portion of harvest.

Currently, Michigan small fruit industry is getting closer to finishing one of the toughest growing seasons of the past five years. Weather conditions at the beginning of spring caused substantial loses to strawberries and blueberries. In strawberries, mild winter temperatures and spring frosts affected summer strawberry fields by damaging early flowers, mainly the king blooms which yield the largest fruits. Since only secondary and tertiary flowers were unaffected, fruits were small, affecting the yield and quality of harvest.

In addition, unseasonably high temperatures during spring also invited the early presence of insects that in strawberries caused serious damage to early season varieties. Flower thrips caused extensive “bronzing” in some fields rendering the fruit unmarketable.

For blueberries the situation was similar, early spring frost damaged around 20-30 percent of the early bloom affecting the quality and size of the crop. However, not all varieties were affected nor were all production areas. Most affected fields were located in southwest Michigan where Jersey and Elliott varieties were seriously affected. In addition, a summer drought occurring during August (the region received less than 1.5 inches of rains) seriously affected Jersey and Elliott fields. Because of the lack of rain or supplemental irrigation, fruit shriveling caused substantial fruit drop, especially around Van Buren and Allegan.

Presently, harvest of fall raspberries is in progress. So far, few problems are reported by growers. The fruit quality is very good, no fruit rots reported, and spotted wing Drosophila (SWD) control has been excellent. The good weather over the past week helped growers to maintain plenty of customers at U-pick farms. Ripe fruit is removed on a daily basis and what remains unharvested by customers, growers are sending pickers to harvest ripe or ripening fruit left on bushes. This practice combined with a rigorous spray program is achieving excellent control of SWD, even in fields that were unable to control it last year.

For blueberries, harvest is ending with only a few fields in Ottawa, Muskegon and Oceana counties still harvesting Elliott and Aurora and other late season varieties. Mechanical harvest in southwest Michigan has finished, and in northern counties it is expected to continue for another two more weeks.

Regarding the main problems observed in blueberries during this season, the lack of SWD control at some fields caused substantial losses in Allegan and Van Buren counties. The early arrival of the pest made the problem especially bad during the last two weeks of July and the first week of August when a combination of high temperatures, and the need for sprinkle irrigation created conditions that made it difficult to maintain an SWD-free crop. However, the damage was more in mechanical-harvested fields than in hand-harvested ones. Daily removal of ripening fruit and a tight spray program minimized the SWD impact.

At this time, growers need to maintain a good disease management program. Especially in fields that in the past have presented early defoliation due to leaf rust. So, please check your foliage for symptoms of leaf rust and immediately apply the recommended control measures, if detected.

Another problem that mechanical harvested fields are currently showing is plant injury caused by the harvester. In addition, Phomopsis cankers are already visible. This is the time to prune and remove all infected or damaged canes and apply a fungicide to prevent spread of Phomopsis in your field. For recommended fungicides and doses, please check the Michigan Fruit Management Guide (Extension Bulleting E154). You may also call your local MSU Extension office for assistance.

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