West central Michigan small fruit regional report – May 24, 2016

Cherry fruitworm biofix dates have been set for Allegan and Van Buren counties, and no cranberry fruitworm moths have been detected yet.

So far, weather conditions in west central Michigan have continued improving, allowing plants and insects to proceed in their normal cycle. For the past seven days, minimum daily temperatures in the area were around 42 degrees Fahrenheit and the maximum around 75 F. That allowed a growing degree-day (GDD) accumulation of approximately 320 GDD base 50 F.

On the other hand, after a period of high humidity that prevailed during the early portion of May, we are in a dry period. No rains have been reported in the area since May 14 when in some places the precipitation reached around 0.3 inch. This lack of rain is occurring at a critical time for some small fruit crops such as strawberries and blueberries that are in full bloom. During this period water deficits may affect pollination and fruit set if supplemental irrigation is not provided.

Strawberries are in full bloom with early season varieties already entering the petal fall stage. No late frosts have been reported and the crop proceeds without problems. Supplemental irrigation is needed to maintain the crop in good conditions.

All blueberry varieties are in full bloom. Dry conditions from the past seven days have prevented the development of early season blueberry disease such as mummy berry shoot strike and Phomopsis twig blight. However, the appearance of shoestring virus infections in susceptible varieties is already evident, especially in the variety Elliott. Although no cure exists for this virus infection, this is the time to scout fields in search of infected plants to mark them for removal. After two years of bad winter weather that left many fields in bad shape, shoestring virus-infected plants are not going to recover, and removal is a priority to prevent the dispersal of the virus to healthy plants.

Insect pest management is the main priority in blueberries. So far, only cherry fruitworms have emerged from diapause. The first moths were detected in Van Buren County on May 13 and in Allegan County on May 16. At both locations, sustained moth capture has continued. Therefore, May 13 could be considered the biofix date for Van Buren County, and May 16 for Allegan County. According to the cherry fruitworm degree-day model on Michigan State University’s Enviro-weather, the first eggs should be found after May 26 at blueberry fields located around Grand Junction, Michigan.

Cranberry fruitworm emergence is expected this week, and the first eggs should be found shortly after (see table below). According to the cranberry fruitworm degree-day model on Enviro-weather, there is a 30-40 degree-day separation between cherry fruitworm and cranberry fruitworm oviposition once they are out. Therefore, timing your next insecticide application against fruitworms should be based on the cranberry fruitworm degree-day model. Check the Enviro-weather website for fine-tuning your application according to the weather station nearest your farm.

Fruitworm development in Michigan according to phenology models


First adults

First eggs

Current degree-day accumulation (5/24/2016)

Grand Junction


West Olive

Cherry fruitworm

238 ± 30

432 ± 15




Cranberry fruitworm

375 ± 20

460 ± 20




If you need assistance with your fruitworm control including selecting insecticides or Enviro-weather, contact your local MSU Extension fruit educator or contact me at 616-260-0671 or garcias4@msu.edu.

Good Agricultural Practices (Gap) training for Hispanics

The FDA Food Safety Modernization Act (FSMA) Produce Safety rule is now final, and the earliest compliance date for some covered farms is two years after the effective date of the final rule (FDA 2015). However, some previsions will take place September 2016. The rule establishes science-based minimum standards for the safe production of fruits and vegetables for human consumption. MSU Extension in cooperation with Michigan Food and Farming Systems is programming several GAP workshops in Spanish for this 2016 crop season.

The first workshop is Friday-Saturday, June 3-4, 2016. Training will take place at the MSU Trevor Nichols Research Center in Fennville, Michigan, and the hands-on session will take place at selected farms participating in the training. This training will facilitate growers’ compliance with the minimum requirements demanded by the FDA and buyers. All training will be conducted by the fruit MSU Extension produce safety team members: Carlos García-Salazar, Phil Tocco, Anamaría Gómez-Rodas, Mark Longstroth, also Filiberto Villa from MIFFS as collaborator.

Growers and farmworkers participating in this training will receive a certificate of completion of training. Blueberry growers and other fruit growers in Kent, Ottawa, Allegan, Van Buren and other neighboring counties are encouraged to send their Spanish-speaking farmworkers to take advantage of this training to comply with the new FSMA rules. For a complete description of the program, see a flier in Spanish or the article, “GAP training for Hispanic growers June 3-4, 2016.”

There will be a recuperation fee of $30 per participant that will cover materials, refreshments and lunches. To register your workers or yourself, contact Filiberto Villa at 269-830-2309 or filibertovilla@sbcglobal.net.

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