West central Michigan small fruit regional report – June 9, 2015

Prevailing weather conditions are favoring plant growth, development and emergence of pests and diseases, including large populations of cranberry fruitworm and Phomopsis twig blight and canker.

Although daily maximum temperatures have been around the low 70s, they have provided suitable conditions for the appearance of large populations of fruitworms and blueberry and strawberry diseases. Average maximum daily temperatures for the past five days have been 72 degrees Fahrenheit, and average minimum temperatures were 66 F. These temperatures allowed a growing degree day (GDD) accumulation (base 50 F) of 557 GDD for most of the central region. No substantial rain occurred during the past five days, thus growers are applying supplemental irrigation to most small fruit crops.

Early varieties of strawberries in central Michigan have started ripening. There are some problems related to common leaf spot disease that affected early varieties, and in some instances there has been a considerate amount of damage.

In blueberries, we continue observing cane collapse in fields that only a few days ago were fine. It seems there is an abundant source of inoculum coming from disease-infected canes that were affected by winter, but early in the season were not showing symptoms of disease infection. Growers need to treat affected fields with recommended fungicides to prevent infections on the new growth.

So far, the main cane disease problem seems to be related to Phomopsis twig blight and canker. However, Michigan State University Extension’s small fruit plant pathologist is conducting a laboratory analysis to identify the pathogen responsible for this disease outbreak. In the meantime, growers need to continue with their fungicide spray program using recommended fungicides for Phomopsis and fruit rots. For recommended products and amounts, consult the “2015 Fruit Management Guide” (Extension Bulletin E0154).

In addition to plant diseases, during the past week we observed a large emergence of overwintering cranberry fruitworm adults. This large presence of cranberry fruitworms represents a potential problem for blueberry fields if timely applications of insecticides are not conducted. For growers that need to spray fungicides and insecticides for cane diseases and fruitworm control, it is necessary to remember that Pristine is not allowed to be mixed with other products. So, if you need to mix a fungicide and one insecticide for your next application, consider fungicides other than Pristine. The “2015 Fruit Management Guide” provides a number of products that are available for application.

Spotted wing Drosophila training update

We would like to remind growers we are offering the first spotted wing Drosophila training session on Monday, June 15 at the Board Room in the Ottawa County Fillmore Complex in West Olive, MI. Although the program emphasizes the use of MSU Enviro-weather, you do not need to be a computer-savvy person to attend the training. For this reason, the hands-on practice to access MSU Enviro-weather is designed for people with limited skill on the use of computers. We will provide personal attention to all trainees and make sure they have access to a computer. You do not need to bring a computer if you do not have one, but if you have a laptop and want to bring it, that will be great. Gowers attending this workshop will receive four RUPs. To register online and view the event flyer, go to the 2015 Spotted Wing Drosophila Workshop Event page.

IPM twilight meetings

The last two meetings for this blueberry growing season have been set for Tuesday, June 16. The first meeting will be in the early afternoon in Van Buren County at Beeches Golf Club9601 68th Street, South Haven, MI 49090, from 1:30- 3:30 p.m. The second meeting will be in the evening at the Ottawa County Fillmore Complex, 12220 Fillmore Street, West Olive, MI 49460 from 6-8 p.m. For more information, see “2015 Blueberry pre-harvest meetings set for June 16.”

For assistance or more information on any of the topics presented here, contact your MSU Extension county office or contact me at 616-260-0671 or garcias4@msu.edu.

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