Wild Blueberry Newsletter May 2022

Wild Blueberry Newsletter header graphic, text and a photo of blueberries and leaves

May 2022


Dear Growers, Processors, and Stakeholders,

Time to Sweep for Spring Insects!

Blueberry spanworm

Is primarily a pest during bloom in crop fields and leads to delayed emergence in prune fields.  We have already had reports of damage in crop fields in the Midcoast. Damage can vary and may be confined to small areas or be widespread. Use a sweepnet to scout for larva of this pest now. Higher pressure this year is likely related to adults emerging earlier than normal last year. In crop fields, we have a threshold of 10 larvae per set of 10 sweeps and in prune fields 5 larvae per set of 10 sweeps. Only larvae can be targeted for control. Products containing Bt work against the larve as will methoxyfenozide (such as Intrepid 2F), consult the 2022 Pest Management Guide for rates.

Blueberry flea Blueberry

Blueberry flea beetleIs also mainly a pest before or during bloom, however, in some years large larvae can be found in fields after bloom. Use a sweepnet to scout for the small black larval stage of this pest now. If you only find large larvae (~3/8 inch long) present in your field, most of the population could have already burrowed into the soil to pupate. Spraying at this time will not be effective because some of the population is safe (in the soil). Threshold levels for the adults are 30-50 adults per 10 sweeps. Mark the area to treat early next spring.

In the prune year, Imidan, Delegate or Assail is recommended to control larva. A biological control for blueberry flea beetle larva is Beauveria bassiana, sold as Botanigard ES. The adults are less susceptible than the larvae. A rate of 1qt / acre is recommended, sprayed in the late afternoon or evening. In addition, Entrust (organic formulation of spinosyn) can be used for adult flea beetle control. However, controlling adults is tricky and not always successful. Because of this, it is recommended that where adults occur in high numbers record the fields and monitor these fields the following spring. Use larval control tactics if the fields warrant it in the spring. Remember burning will eliminate eggs, but it needs to be a hard burn.

Cold Temperature Damage vs. Mummy Berry vs. Botrytis

We are still having some chilly nights in the thirties and dropping down to the twenties making it possible that there could be a period of cold temperatures during bloom – although we hope not! Cold temperature events can damage flowers visibly by browning the flower (picture below), but also internally. Internal damage may not appear until after fruit set when a lack of fruit development is observed. If cold temperatures occur, you can check the green fruit in your field for cold damage by cutting fruit open. Undamaged berries will be green inside, while damaged berries will be brown inside.

Flowers can also be killed by a variety of diseases (see photos below). Mummy berry infection has already occurred and symptoms are starting to appear on diseased flowers. Typically, the infected flowers are killed when they are still closed and you will see grey/silver spores at the base of the flowers (see yellow circle). Flowers may also be killed by Botrytis and those will have black hairs sticking out of the dead flowers (see yellow circle).

Temperature effects on wild blueberry flowers and leaves according to Hall et al. 1971, Hall and Hildebrand, 1988, and Hicklenton et al., 2002.

Temperature damage table

Cold temperature damaged photos


Upcoming Events

Organic Field Meeting (1 PA Credit)

Blue Hill Berry Co.
May 20th (Friday)
UMaine Field Meeting: 10:00 am-12:00 pm with Pizza!

The field is behind #365 on Rt 172 and the Surry General Store but do NOT park at the brown house or the store. Park either in the field behind #365, which is a brown house OR across the street in a grassy field labeled for UMaine parking.

Organic management of spring pests will be discussed at one of Blue Hill Berry Co fields in Surry with Drs. Phil Fanning, Seanna Annis, and Lily Calderwood. Lily will also discuss new thoughts and research results on crop management practices.

Downeast IPM and Crop Management Field Meeting @ BHF (2PA Credits)

Blueberry Hill Farm
May 25th (Wednesday)
UMaine Field Meeting: 10:00am-12:00pm
Commission Listening Session: 12:00-2:00pm with LUNCH
1643 US-1, Jonesboro

Management of spring pests will be discussed with a boom sprayer coverage demonstration. This meeting will be followed by a Wild Blueberry Commission of Maine Listening Session where lunch will be available.

Downeast IPM and Crop Management Field Meeting (2PA Credits)

Harmon Mountain Farm, Ethan Davis
June 9th (Thursday)
UMaine Field Meeting: 2:00-4:00pm
2001 Northfield Rd, Northfield

Harmon Mountain Farm is now under new management after the Antil’s retired. Join us to connect with each other and learn about pest and crop management with new energy!

Mid-coast IPM and Mulch Field Meeting (2PA Credits)

Brodis Blueberries, Ron Howard
June 14th (Tuesday)
UMaine Field Meeting: 4:00-6:00pm
Commission Listening Session: 6:00-8:00 pm with DINNER
87 Jones Hill Rd, Hope (Off of Rt 235, cannot access via Appleton)

Join us at Brodis Blueberries to connect with other growers, learn about pest and crop management, and see a large-scale mulching in action. This meeting will be followed by a Wild Blueberry Commission of Maine Listening Session where dinner will be available.

Fresh Pack Line Meeting

Welch Farm, Lisa, and Wayne Hanscom
July 7th (Thursday)
UMaine Barn Meeting: 10:00 am-12:00 pm with Pizza!
186 Roque Bluffs Rd, Roque Bluffs

Welch Farm invested in a new fresh pack line from the Maine Wild Blueberry Equipment Company in 2021 and Dr. Lily Calderwood has a cold storage demonstration at their farm. Come discuss fresh pack line improvements and berry quality with us!

Blueberry Hill Farm Field Day (2PA Credits)

July 14th (Thursday)
UMaine Event: 9:00 am-3:00 pm with Burgers, Ice Cream, and more!
Blueberry Hill Farm, 1643 Rt 1, Jonesboro

This year’s big field day will feature a morning of IPM with UMaine researchers, burgers on the grill for lunch, followed by an exciting afternoon with the following sessions: Improved Harvesters, Fresh Pack Technology, Drought Management, and Commission Updates.

Interested in getting a ride to this field day? We would like to offer a carpooling option for anyone in Southern or Midcoast Maine who would like to attend the Jonesboro field day. If there is interest, the van or bus will leave from a Midcoast location at 7:00 a.m. and depart Jonesboro at 3:00 or 4:00 p.m. (TBD). Please call Mary Michaud 207.581.3175 for more information.

Zoom Commission Listening Session

September 13th (Tuesday)

Commission Event: 4:00-6:00pm

Password: 914720
Meeting ID: 870 9973 3874
Telephone: (312) 626 6799