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2012 Newsletters - Wild Blueberry Newsletter – April 2012

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wild blueberry newsletter headerApril 2012

Integrated Crop Management Field Training Sessions
Field training sessions will be offered at three locations to demonstrate and discuss the Integrated Crop Management (ICM) field scouting techniques in Wild Blueberry Fact Sheet No. 204.  The first and second session will cover mummy berry blight identification and monitoring, insect sweeping and identification, and weed identification and management.  The third session will cover blueberry maggot fly trapping, leaf and soil sampling, and weed identification and management.  One re-certification credit per session will be offered for certified pesticide applicators.

All Field Training sessions will be from 6:00 to 7:00 p.m.
Field Day Session Location
Knox/Lincoln Counties
Tuesday, April 24, May 29, and June 26
Charles and Dorothy Dolham’s on Rt. 235, 2740 Western Road, Warren
Washington County
Wednesday, April 25, May 30, and June 27
Blueberry Hill Farm, Route 1, Jonesboro
Hancock County
Thursday, April 26 May 31 and June 28
G. M. Allen’s Freezer on Route 15, Orland

Maine Wild Blueberry Crop
Maine’s 2011 wild blueberry crop totaled 83.1 million pounds according to the Maine Wild Blueberries report issued by the New England Crop Reporting Service. For details see .

2012 North American Blueberry Production

2012 North American Blueberry Production

The cultivated blueberry crop in the U.S. was 427.9 million pounds with 227.6 fresh and 200.3 processed. With the wild blueberry crop in Canada at 132 million pounds and the cultivated blueberry crop in British Columbia at 95 million pounds, the total North American crop in 2011 was 738 million pounds.

Updated and New Fact Sheets Available
Wild blueberry fact sheets 209, 219, 239 and the 2012 Maine Wild Blueberry Pesticide Chart have been updated and mailed to growers on our mailing list, along with two new fact sheets: Spotted Wing Drosophila Traps and Targeting the Prune Year Field for Blueberry Maggot Management.  These fact sheets are also posted on our website for viewing and printing,


Importance of Proper Weed Control
A wide variety of woody and herbaceous species native to Maine occur naturally in Maine’s wild blueberry fields. Any plant in a field other than a wild blueberry plant is considered a weed. The wild blueberry competes with weed species for space, water and nutrients. This competition usually results in a reduction in crop yields and prevents the blueberry from spreading. The figure below shows the reduction in blueberry yield from over 5,000 lbs./a to 1,000 lbs/a as the weed cover is increased from zero to 100% over shading the blueberries. Weeds may contribute distasteful fruit such as bunchberries and chokeberries, which reduce the quality of the processed pack and hinder harvest. Weeds also reduce the quality of the fruit by crushing and cutting of the fruit when harvested. Use of both herbicides and cultural tools such as the use of sulfur to reduce the soil pH and weed competition, cutting woody weeds and mulch to encourage spread are all needed to be successful in managing weed competition.

Figure 1. Yield from Untreated Plots by Initial Weed Cover on Percent from All Years

If weeds are not controlled first, then the benefits of fertilizer, pollination and irrigation will not be fully realized. In the past a single pre-emergence application of Velpar could control most weeds but as it has been used over 30 years, resistance has developed and now rotation or combining other herbicides with different modes of action are needed to get good control. The 2012 Maine wild blueberry pesticide chart has identified group numbers of the herbicides registered – it is necessary to use combinations of different groups to get good control.

Successful weed management requires the integrated use of chemical and cultural methods. Knowing the weeds present, the proper method and timing of controls, and following labeled herbicide rates will decrease weed competition and increase the productivity of your field.  Successful weed management does not mean a completely weed-free field but to get adequate weed suppression to increase blueberry yields and maximize your returns. A higher rate of an herbicide would produce a cleaner field but may not result in higher yields. If the rate is too high, it may actually result in a decreased blueberry yield from injury to the blueberries. Concentrating efforts on fast spreading weeds and those that are highly competitive will produce the highest return for efforts expended.  More details may be found in Wild Blueberry Fact sheet 236

Mummy Berry Blight Scouting
Mummy berry disease can cause serious loss of yield by blighting the stems but by the time you see the damage it is too late for control, so if you have had this disease in the past then protective treatments need to be applied to prevent injury. For details see Wild Blueberry Fact sheet 217,  A Method to Control Monilinia Blight .

Information on the progress of the disease and treatment timings will be sent to growers on our email list. You can also call our hot line for information 1-800-897-0757 x 3 or you can find information on our Wild Blueberry Blog at  Putting out mummy berries in your field will allow you to more accurately monitor the disease and reduce the number of fungicide sprays needed. This method is illustrated in the Mummy berry Disease Forecasting Method  PDF on the wild blueberry website. Once bloom occurs, you scout your fields to look for blighted stems and blossoms to get an indication of how well your treatments worked and to assess the potential for disease pressure in the next crop.



David E. Yarborough
Extension Blueberry Specialist

Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.


Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

Call 800-287-0274 or TDD 800-287-8957 (in Maine), or 207-581-3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit

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