May 23, 2017

West central Michigan blueberry growers receive heads up

Spring frosts caused some damage to blueberries and strawberries but no significant impact will be observed on most berry crops in west central Michigan.

For the past two weeks weather in west central Michigan was cold with light rains and a continued threat of spring frost damage to blueberries and strawberries. However, overcast conditions and rains present during this period prevented temperatures from going below freezing. Daily temperatures for the past seven days have been on average 59 degrees Fahrenheit with an average minimum temperature of 50 degrees and a maximum of 59 degrees Fahrenheit. Present weather conditions are slowing down both plant and insect growth and development. So far, degree day (DD) accumulation (base 50 degree Fahrenheit) since March 1st varies from 340 around West Olive, MI to 420 DD around Grand Junction, MI.

Currently, blueberries are in full bloom in counties north of Allegan County and at petal fall in southwest counties, Van Buren, Berrien, etc. At this time, major concerns for blueberries are preventing mummyberry shoot strike and the transmission of the pathogen to flowers (that may result in fruit infections later on), and insect pests. Among recommended fungicides to prevent mummyberry infections and Phomopsis twig blight we have Quash (2.5 oz/acre), Proline (5.7 fl oz/acrea), Quilt Xcel (14-21 fl oz/acrea) among others (for a complete list of recommended fungicides please consult the Michigan State University Extension Bulletin E-154).

The other concern are fruitworms. Due to low temperatures prevailing for the past two weeks insect pest phenology was delayed and no adult fruitworm flight was reported until last week. The Cherry Fruit Worms (CFW) started flying in blueberry fields in Allegan and Van Buren County. So, we can use trapping data collected last week to set the biofix for our CFW model (check the Enviroweather web site). Last week we observed the first pick of CFW flight around the Grand Junction, MI area. Therefore, growers with early season varieties already at petal fall should be ready to apply the first insecticide application against the CFW. Likewise, the Cranberry Fruit Worm (CBFW) is already out. Accordingly, the biofix date to program the insecticide application around Grand Junction should be May 19, 2017. However, growers should use their own fruitworm trapping information to set the biofix date for their particular fields. To adjust the predictions for the beginning of the CFW or CBFW egg-lying period at your farm using your own trapping data please visit the Michigan State University Enviroweather and enter the day when you observed the first adult CFW or CBBFW in your traps in the corresponding box. This will be your biofix date to start the prediction for the date when the egg-lying period will start at your farm.

2017 Systems Approach to Manage the Spotted Wing Drosophila (SWD): IPM training for Berry Growers.

The small fruit team will conduct the first 2017 SWD workshop on Monday June 5, from 9 a.m.-4 p.m., in the Training Room at MSU Trevor Nichols Research Center, 6237 124th Avenue Fennville, Michigan.

Why should growers attend this workshop?

In 2015, 50 percent of the growers attending similar training and after applying what they learned reported benefits including: one or two applications less than in 2014 and average pest control expenses of $175 versus $375 per acre in 2014. In addition, in 2015, those attending the training reported crop losses due to SWD averaging 9 percent of their crop versus 18.5 percent in 2014.

We recommend that growers participate in this training since controlling the Spotted Wing Drosophila remains a major issue for most of the industry. Learning to adjust their pest control program according to changing conditions of weather, plant and insect phenology is critical to save money, resources and obtain a successful SWD control. Please see the attached program for agenda and registration information. Also, to register online please check this link.

– Carlos Garcia, Michigan State University Extension