Pheromone may be key to tipworm control Research finds no connection between cranberry and blueberry pests.


plant material from elsewhere, she notes. By Judie Steeves D


espite their similar looks, the Blueberry Gall Midge and Cranberry Tipworm are different species that give off different pheromones, don’t mate with each other and have different genetics, reports Sheila Fitzpatrick, a research entomologist at the Pacific Agri-food Research Centre at Agassiz.


Initially, she says, the midge was believed to move from blueberries, where it causes minimal damage, to cranberries, where it is an expensive pest.


On cranberries, growers can experience a 20 per cent yield loss in a year from the damage done on the growing tips of the cranberry plant by the tipworm. That loss figure is a grower estimate, not the result of scientific study, Fitzpatrick notes, but one that becomes even more significant as time goes on.


The discovery means the pest didn’t move from blueberries to cranberries, but probably arrived in infested


This summer, the plan is to test a pheromone developed to attract adults to it, so that can be used to monitor populations by luring and trapping adults.


Weekly monitoring will help to


Cranberry tipworm larvae.


determine at what stage populations of the pest are so that decisions about controlling it can be made. They have also discovered the pest produces more than two generations a year, with the first adults appearing in late April or early May. Fitzpatrick is hopeful that by next


summer a pesticide will be registered to combat the pest in cranberries: Movento (spirotetramat). She has found tiny parasitic wasps in 18 per cent of tipworm-infested shoots in 2009 and 2010, so the wasps are providing a small degree of biological control of tipworm, she says.


However, at present, the magnitude of biological control achieved by the wasps is not enough to make an economic difference, she reports.


20 British Columbia Berry Grower • Summer 2012


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