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2011 Newsletters - Wild Blueberry Newsletter – June 2011

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wild blueberry newsletter headerJune 2011

Wild Blueberry Field Day

The annual summer field day for wild blueberry growers will be held on Wednesday, July 20, 2011 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.

2011 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 – 11:30 A.M. Wild Blueberry Association of North America Marketing Update – Mike Collins, Food and Wellness Group
11:30 – 1:00 P.M Cookout
1:00 – 3:30 P.M. Research Talks/Demonstrations

  • Mummy berry Forecast Demonstration – Seanna Annis, UMaine
  • Predation of Insect Pests, Seeds, and Fecal Matter in Blueberry Fields – Matthew Jones, UMaine
  • Native Pollinators and Pollination - Sara Bushmann, UMaine
  • Frost Tolerance in Various Blueberry Clones During Bloom – Lee Beers, UMaine
  • Blueberry Tip-midge – Should We Be Concerned? - Frank Drummond, UMaine
  • 2011 Pollination Levels Across Different Blueberry Management Systems – Frank Drummond, UMaine
  • Stimulating Rhizomes with Growth Regulators - Brad Libby, UMaine
  • Weed Management Research for 2011 – Dave Yarborough, UMaine
  • Demonstration of BlueMax Harvester- Chris  Dreher, Union Farm Equipment

Two recertification credits

Organic Blueberry Meeting

The University of Maine is sponsoring an organic wild blueberry meeting on Monday, July 18th at 1:00 p.m. at the Coastal Mountains Land Trust Beech Hill Preserve in Rockport.  Here are the directions from Route 1 in Rockport heading south. Take a right onto Beech Hill Road across from Hoboken Gardens.  Go about a mile, parking lot is on the left just past the old gate to Beech Hill and a stone wall – see Delorme Maine Atlas and Gazetteer Map 14, E-3 or visit Other organic growers will be present to discuss the challenges of growing wild blueberries organically.

Valdensinia Leaf Spot – the “new” leaf spot

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 have already started appearing in your field and will continue to appear as more rain occurs.

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 infected first.  Young leaves will drop off while still green and with only a few spots.  This disease causes leaf drop a few days after the first infection (May or early June) and continues through July.  This leaf drop early in the season will cause a decrease in flower buds in prune year plants and decreases in yield in crop year plants.  Older infected leaves will remain on the plant and can be seen until normal leaf drop in the fall.  See wild blueberry web site at

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

If you suspect you have this disease, please contact Seanna Annis or Dave Yarborough at 1-800-897-0757 (blueberry hotline) or send us a sample so we can confirm that you have the disease before you attempt control measures. You can get information on control of this disease from the links provided above or from Seanna Annis. She 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 tends to have smaller, more numerous spots. You will start to see very small (pinprick) spots in mid June which will grow bigger over the season.  Septoria leaf spot appears as many smaller spots, that are not circular, and have dark red/brown centers. “False Valdensinia” leaf spot is another disease that produces larger reddish/brown leaf spots that usually show up in July and August.  Heavy infections by both Septoria leaf spot or “false Valdensinia” leaf spot can cause leaf drop in mid-July and later with dry conditions but often does not significantly affect yield since the leaves are falling off  later in the season. 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.


Monitoring for Blueberry Fruit Fly

Blueberry fruit fly sticky traps should be placed out in your fields in June when about 10% of the blueberries turn blue.  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, 2011 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.

Time for Leaf and Soil Samples

Leaf samples should be taken at the tip-dieback stage of blueberry growth (usually around the 4th of July but may be later 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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