West central Michigan small fruit regional report – May 26, 2015

Last week’s frosts did not have a significant effect on small fruit crops around west central Michigan. Temperatures dropped to the upper 20s and low 30s, but no frost damage was reported on strawberries or blueberries.

West central Michigan experienced several days with freezing temperatures, causing patchy frost in some areas. On May 20, reported low temperatures around Belding, Michigan, ranged from 28 to 31 degrees Fahrenheit. Other places like Sparta, Fremont and Hart, Michigan, also experienced below freezing temperatures, but no damage to small fruit crops was reported. In addition to low daily temperatures, no significant precipitation occurred during the past week. During this period, prevailing weather conditions included daily temperatures averaging 55 F with an average maximum temperature of 66 F and an average minimum of 44 F. Currently, growing degree days (GDD) base 50 F accumulation for the area is around 362 GDD.

Past week’s temperatures were not conducive for a rapid plant growth and development. Thus, blueberry varieties like Jersey and Elliott are still in full bloom, while Bluecrop, Duke and other early varieties are in the petal fall stage. In strawberries, late season varieties are in full bloom and early varieties are in late bloom to petal fall with some green fruits already present. Meanwhile, brambles are in the shoot development stage without any reported problems.

In blueberries, fruitworms are already active in southwest counties. Cherry fruitworm adults are flying and we expect the first oviposition at the end of this week. Growers will have 80-100 GDD after that to apply the first spray against fruitworms. Cranberry fruitworms have not emerged, but we expect the first adults to appear this weekend in southern counties. Once adults emerge and the oviposition begins, spray applications for cherry fruitworms will also cover the first portion of the cranberry fruitworm larvae population. Even though cherry fruitworms emerged earlier than cranberry fruitworms this year, the first application for either one of these two insects will be effective to control both fruitworms.

Below is an up-to-date table with the GDD summary for both species and expected dates for the presence of adults and eggs at different locations around west Michigan.

Predicted degree days for appearance of overwintering fruit adults and first eggs


First adults

First eggs

Current degree day accumulation (5/26/2015)

Grand Junction


West Olive

Cherry fruitworms

238 ± 30

432 ± 15




Cranberry fruitworms

375 ± 20

460 ± 20




Michigan State University Extension recommends growers visit the MSU Enviro-weather website and check the weather extended forecast and the cranberry fruitworm GDD model for more up-to-date information on the progress of the fruitworm phenology around Michigan.

Spotted wing Drosophila training update

We will be offering the first spotted wing Drosophila (SWD) training session June 15, 2015. This is our first SWD training for this season and will include a classroom and a hands-on session. In 2015, we are putting emphasis in training growers and integrated pest management (IPM) consultants on the use and management of the insecticides currently recommended for SWD. The objective is to provide the necessary knowledge to understand how insecticides perform under a variety of weather conditions so growers and IPM practitioners can make informed decisions about when and how to utilize each one of the recommended insecticides.

The program also emphasizes the use of MSU Enviro-weather to plan your insecticide applications and select the best products or tools depending on the current weather forecast. Online registration and a flier will be available soon at the MSU Extension Fruit and Nuts Events page.

For assistance or more information, contact your local MSU Extension office or me at 616-260-0671 or garicias4@msu.edu.

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