MSU Extension

Environmental conditions in the central region remain conducive for slow plant development and little accumulation of Growing Degree Days (GDD). For the past week, in the Ottawa and Allegan region, high temperatures have been around the low 60s (61°F average) and the lows in the 40s (40°F average). These conditions are an improvement in relationship to the previous week. Rain has been absent for the most part with little accumulation; less than 0.5 inches. So far, degree day accumulations in the area have reached 135-143 GDD (Base 50°F) and 318-338 GDD (Base 42°F).

Despite the low degree day accumulation, small fruit crops have moved along very well, although their growth and development is more than one week behind in relationship with the previous year. For example, summer raspberries are still in the leaf unfolding stage and fall raspberries in the cane emerging stage, however, their growth is very healthy at this time.

Regarding blueberries, growth stages go from early pink bud in late season varieties (Elliott) to late pink in the most advanced varieties like Bluecrop. Winter damage is showing more intense in blueberry fields north of Ottawa County. In those fields, Bluecrop and other early varieties are presenting damage that is taking not only shoot tips, but whole canes. These fields require extensive pruning of damaged tissues and fungicide treatment to prevent cankers.

Regarding blueberry diseases, mummy berry mushrooms are drying out. However, there are some new coming out of mummified fruits. The number is small and the size of the cup is only 2 or 3 millimeters in diameter.

With respect to insect pest problems in blueberries, there will be enough degree day accumulation during the rest of the week to start the emergence of the cherry fruitworm, especially in the Allegan area. Traps need to go out in preparation for the fruitworm pest control season.

Also, at this time, it is important that blueberry growers with fields showing extensive winter damage pay attention to the mummy berry control. This is very important in fields with a history of mummy berry or that had mummy berry problems at harvest during the past year. Winter damage is also a port of entry for phomopsis twig and shoot-canker. The combination of winter damage and phomopsis is very destructive, especially for small plants. In newly planted fields, this might destroy up to 50 percent of the young plants. If you see dieback problems in your field and you are not sure if this is due to winter of phomopsis, please call your local county Extension office for assistance, or take shoot samples and send them for identification to the MSU Diagnostics Lab. Products recommended for early season mummy berry and phomopisis control are Indar 2F (6 fl oz), Indar 75 WSP (2 oz), or Orbit (6 fl oz). For a complete list of products and recommendations for mummy berry and phomopsis control, please follow the 2011 Michigan Fruit Management Guide (MSU Extension Bulletin E-154).

On June 1, we will be hosting another training workshop for berry growers interested in learning about the biology, monitoring and control of the spotted wing Drosophila (SWD). Growers, berry crop scouts, and IPM consultants should attend this workshop. Training will start with classroom training followed-up by hands-on field training by MSU experts on this new invasive insect. Participants will learn how to identify this new insect, how to trap for it, and how to sample fruit. This program is designed for growers, scouts and consultants to learn about SWD before the field season starts, so management of this pest can be integrated into IPM programs. This training will be conducted at the Trevor Nichols Research Center, 6237 124th Avenue, Fennville, MI 49408. There will be a $25 registration fee that includes lunch and educational materials.

Space is limited, so you must pre-register by contacting Judy Hanson at 616-994-4548 at the MSU Extension Ottawa County office in West Olive, Michigan.