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Posted November, 1998

Maine's 1998 Cranberry Harvest Up 75% over 1997 Level

This fall's Maine cranberry harvest has increased by 75% over 1997 levels, according to the results of a survey by Charles Armstrong of Steuben, a University of Maine Cooperative Extension cranberry specialist. Growers produced about 3,500 barrels compared to 2,000 barrels of berries last year.

This year's crop is worth about $210,000. The higher harvest is the result of new plantings coming into production and effective management by growers, Armstrong says. About 80% of Maine's acreage and 90% of this year's production is located in Washington and Hancock counties.

Maine growers currently manage 123 acres of cranberries, not including 57 acres planted by Cherryfield Foods this year. The company's plans to establish 117 acres of additional bogs will more than double the current state total.

Armstrong works with members of the Maine Cranberry Growers Association to apply Integrated Pest Management techniques. He inspects bogs for the presence of weeds, insect pests and diseases and makes recommendations on pesticide applications and other practices. He also helps growers to apply research results from around the country and has collaborated with experts from other cranberry producing states.

Over the past three years, he has maintained an office in the Down East Resource Conservation and Development office in Cherryfield.

The most difficult pest to control, he says, is cranberry tipworm which reduces yields by weakening plants. “Tipworm attacks only the growing tips of the plants. It's a problem in Maine and most other states which grow cranberries,” says Armstrong. It has caused serious losses in Massachusetts and Wisconsin which are the highest producing cranberry states in the U.S.

Tipworm is about the size of a pinhead and reproduces quickly. By causing the plant to reduce flower buds, it can also reduce the following year's harvest. The insect is thought to be dependent on cranberries and goes through up to five generations in one growing season.

A pesticide is currently used to control tipworm, but as a result of suspected resistance by the insect, it does not appear to be very effective in Maine. Armstrong is helping growers to use other techniques such as applying sand to bogs and applying a growth inhibitor. Sand kills tipworm larvae which overwinter on the surface of the bogs.

Growth inhibitors interfere with the tipworm's life cycle by disrupting the molting process and are thus harmless to most other organisms. The particular inhibitors that might be used to control tipworm are still considered experimental and are being tested in Massachusetts and Wisconsin laboratories.

Armstrong would like to see Maine develop a research program focused on the needs of local industry. “For example, our climate affects the timing of insect hatches, and recommendations from other states may not be appropriate for Maine,” he says.

Armstrong has also considered steps to identify insects which could control tipworm naturally. Spiders, a particular syrphid fly, and possibly egg-devouring ladybugs could all provide protection, but so far, they do not appear to be effective.

Armstrong is an entomologist who received his master's degree from UMaine in 1996. He was advised by Stephen Woods, a UMaine faculty member in the Department of Biological Sciences. Armstrong's work with cranberry growers is supported by the Maine State Legislature and Cooperative Extension. He worked for the Maine Department of Agriculture during the first part of 1998 as Interim State Entomologist.

Armstrong maintains an Internet site with information about Maine's cranberry industry at http://nemaine.com/rc&d/cranberry.htm.

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