West central Michigan small fruit regional report – July 8, 2014

Blueberry and raspberry harvest will start this week with excellent quality and good yield. June strawberries, on the other hand, are still being harvested, but will end this week.

Most small fruit crops are already in harvest in west central Michigan with blueberries and raspberries being harvested this week with excellent fruit quality and yield. Prevailing weather conditions have favored a good development of blueberries and raspberries with abundant rain and moderated temperatures. So far, the daily maximum temperature for the past seven days has been 76 degrees Fahrenheit, and the minimum temperature 57 F. As of July 8, the growing degree day (GDD) accumulation since March 1 is approximately 1,038 GDD base 50 F.

Over the past seven days, we had some scattered thunderstorms that brought some hail, causing damage to blueberries in Allegan and Ottawa counties. However, the accumulated precipitation during this period varied from place to place. Some areas reported 0.2 inches or less, but other sites reached up to 1 inch of rain during the same period.

Currently, strawberry harvest is coming to an end in most places in west central Michigan and field renovation will proceed soon. Regarding summer raspberries, they are in harvest in Allegan and Ottawa counties. Fruit is of good quality and yields are excellent. It seems that raspberries suffered little or no damage due to winter. So far, no issues related to diseases or insects have been reported, but growers are sampling the fruit and sorting out any fruit with symptoms of disease or insect damage that might show up at harvest.

Blueberry harvest has been initiated in Van Buren and Allegan counties. Fields with varieties such as Wayman, Duke and some Bluecrop are hand-harvested. However, growers with no access to labor are machine-harvesting, but only in small quantities. In general, fields north of Allegan County are between 10 and 20 percent blue with the early varieties such as Duke ready for harvest at the end of this week. We have seen only a few problems related to fruitworms and plum curculio that were controlled on time without any problem.

Weeds, on the other hand, seem to be a problem that growers need to take care of before harvest. The weed problem is more related to perennials that have been difficult to control due to weather conditions early during the season. It is important to have a good weed control to facilitate spotted wing Drosophila (SWD) management. Weeds are a refuge for SWD flies and can provide protection from insecticide applications, especially if those weeds are brambles.

Regarding insect pest control, Michigan State University Extension has deployed SWD traps in Allegan, Ottawa, Kent, Ionia and Mecosta counties. Also, brown marmorated stink bug traps have been deployed in Allegan and Ottawa counties and they will be also deployed in Mecosta County this week. Traps have been monitored one or two times a week, depending on the crop. This week we found a single SWD female in a trap located in a blueberry field at Glenn, Michigan. Also, a SWD larva was found in June strawberries in Ottawa County. No flies have been found in other blueberry or strawberry fields.

Our current recommendation is not to start the SWD control if your blueberry crop is still less than 5 percent blue. However, for raspberries it is necessary to apply the recommended insecticides if flies are detected in the SWD traps and you are actively harvesting. Since there is not an action threshold (a certain number of flies per trap) for SWD, the chemical control needs to be initiated as soon as the first flies are trapped in your field (the same applies to blueberries). Raspberry fields with a previous history of two-spotted spider mites need to be careful with using pyrethroid insecticide in excess. Try to rotate your insecticides and avoid back to back applications of pyrethroids.

For recommended insecticides and doses, consult the “2014 Michigan Fruit Management Guide” (E-154). For assistance with SWD identification or insecticide recommendations for SWD management, contact your local MSU Extension office or contact Carlos Garcia at 616-260-0671 or garcias4@msu.edu.

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