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2010 Newsletters - Wild Blueberry Newsletter – June 2010

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wild blueberry newsletter headerJune 2010

Wild Blueberry Field Day

The annual summer field day for wild blueberry growers will be held on Wednesday, July 21, 2010 at Blueberry Hill Farm on Route 1 in Jonesboro.  The meeting will begin at 10:30 a.m. with blueberry growers, processors, and University and government employees, affiliated with the blueberry industry, discussing this year’s wild blueberry crop.  The remainder of the program will provide updates on current issues and research projects as listed below. There will be two pesticide credits offered to certified pesticide applicators for participating in the program.

2010 Wild Blueberry Summer Field Day Agenda
Blueberry Hill Farm
Wild Blueberry Research and Extension Facility

10:30 – 11:00 A.M. Crop Discussion (Light Blue Metal Building)
11:00 – 12:00 P.M. Wild Blueberry Association of North America Marketing Update – Sue Till, Swardlick Marketing Group
Mummy berry Forecast Project and Valdensinia Update – Seanna Annis, UMaine
An Update on Gypsum as an Alternative Fertilizer -James Santiago, John Smagula, UMaine
12:00 – 1:30 P.M Cookout

  • Blueberry Genetics Research Update – Dan Bell and Lee Beers, USDA and UMaine
  • Management of Blueberry Thrips and Spanworm 2010 – Judy Collins, UMaine
  • Research on Native Bee Biology and Ecology – Sara Bushmann, UMaine
  • Stimulating Rhizomes with Growth Regulators - Brad Libby and John M. Smagula, UMaine
  • Weed Management Research for 2010 – Dave Yarborough, UMaine

Two recertification credits

Organic Blueberry Meeting
The University of Maine is sponsoring an organic wild blueberry meeting on Wednesday, July 7th  at 1:00 p.m. on the Hanes Brook Road off Route 9 in Amherst.  Directions from Bangor: On Route 9, the Hanes Brook Road is on the left 4 miles after the Amherst town line marker; From the East on Route 9, it is on the right 2.2 miles after the junction of Route 181.  Researchers from the Systems Approach and SARE research projects will discuss fertilizer and weed suppression projects on the site and the new Systems Approach Study. Other organic growers will also be present to discuss the challenges of growing wild blueberries organically.

Valdensinia Leaf Spot – the “new” leaf spot
Leaves infected with this fungus last year, will have over-wintered on the ground. With the wet weather Maine had in early June, spores will be produced on leaves that were infected with this fungus last year and survived over the winter.  Leaf spots caused by the Valdensinia fungus may start appearing in your field in the next few weeks.

PLEASE scout your field for any areas of leaf drop or leaf spot. You will see large (1/8 to 1/2”), often circular, light brown spots with dark margins on leaves. There may only be one or a few spots on leaves, and the lower leaves will be affected first.  Young lower leaves will be infected first and drop off while still green and with only a few spots.  Disease causes leaf drop starting after first infection anytime from May on and continues through August (see Valdensinia (PDF))

If you suspect Valdensinia leaf spot is in your field, avoid diseased areas and DO NOT enter the field when it is wet.  Remove dead leaves from footwear, vehicles, and equipment before leaving field (fungus can spread by moving infected leaves). More information is available at the blueberry Extension website Valdnesinia Sanitation Protocol (PDF) .

If you suspect you have this disease, then please send us a sample so we can confirm it. You can get information on control of the disease from the links provided above or by contacting Seanna Annis or Dave Yarborough at 1-800-897-0757 (blueberry hotline).  Seanna Annis also needs disease samples for DNA fingerprinting to determine how this fungus is spreading among fields.

Septoria leaf spot is a common disease found throughout Maine. It can be mistaken for Valdensinia leaf spot, but it has smaller, more numerous spots. You will start to see very small (pinprick) spots in mid June which will grow bigger over the season. There will be many smaller, not circular spots, with dark red/brown centers. Heavy infections can cause leaf drop in mid July and later with dry conditions.

Monitoring for Blueberry Fruit Fly
Blueberry fruit fly sticky traps should be placed out in your fields in June. Because of the early season this year you may want to set them out now.  This trapping method will provide you with a reliable method of determining the number and emergence time of the fruit fly. This should be done in every cropping field, since the timing of emergence and fly populations vary widely among fields because of microclimate and past infection levels. Refer to Cooperative Extension Fact Sheet No. 201, Monitoring for the Blueberry Maggot, for details on this practice and fact sheet No. 209, 2010 Insect Control Guide for Wild Blueberries for control measures.  The Phercon AM baited traps may be obtained at some of the county soil and water conservation offices or may be ordered from Great Lakes IPM or call 1-800-235-0285.

Label Changes will Allow for Reduced Water Volume for Insecticide Applications
Assail now has a 10 gallon ground and a 5 gallon aerial application volume 2(ee) label for lowbush blueberry and it is expected that Bayer will also issue a 2(ee) 2 gallon aerial application volume for Provado.  Both of these insecticides are effective in controlling the blueberry fruit fly. You may obtain this label from your dealer or get them on the wild blueberry web site at

Time for Leaf and Soil Samples
Leaf samples should be taken at the tip-dieback stage of blueberry growth (around the 4th of July but may be earlier this year) on pruned fields in order to determine your fertilizer needs for the next crop cycle.  Refer to Wild Blueberry Fact Sheet No. 222, Leaf and Soil Sampling Procedures, for more details.  For a single sample, cut three stems from 30 clones and place them in a paper bag with holes available at your local County Extension office or at Blueberry Hill Farm in Jonesboro.  Keep the samples in a warm, dry spot with the top of the bag open to promote drying.  Bring the sample to your county Extension office, Blueberry Hill Farm or mail the sample to the University of Maine Analytical Lab, 5722 Deering Hall, Orono, ME 04469-5722.  The cost of the analysis is $25 per sample unless you strip the leaves from the stems and include the leaves in the bag, then it is $22 per sample.  Include a check payable to Maine Soil Testing Service with the sample.

Soil nutrient analysis levels are not used to determine optimum wild blueberry production – leaf samples must be taken for nutrient analysis – but soil sampling is necessary to determine the soil pH level.  If the pH is too high, greater than 4.0, then reducing it will discourage weed growth and reduce the need for herbicides. Recent research has shown that it may be done without injury or loss of blueberry production.
Refer to Wild Blueberry Fact Sheet No. 222, Leaf and Soil Sampling Procedures, for instructions for sampling soil. Place samples in a sturdy container, such as a pint ice cream carton or a University soil sample box available at your local county Extension office or at Blueberry Hill Farm.  Indicate pH only on the container, and include a check for $10 per sample. Either mail to Soil Testing Service, 5722 Deering Hall, Orono, ME 04469-5722 or you may also give it to your local county Extension office or Blueberry Hill Farm to be transported to the University of Maine.  The University of Maine Analytical Lab will analyze the samples for available nutrients in the leaves and pH in the soil.  Results will be sent directly to you with the appropriate fertilizer or sulfur recommendations for your field later in the year.



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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