pest management


Trapping the tipworm


Scientists find they can monitor this insect even without the use of costly pheromone bait.


By Judie Steeves O


ngoing research into use of a pheromone to lure Cranberry Tipworm into traps indicates


that producing either the pure pheromone or the synthetic one is too expensive, but there has been a side benefit. Research entomologist Sheila Fitzpatrick of the Pacific Agri-food Research Centre at Agassiz says the pheromone makes a wonderful but costly monitoring tool for the devastating pest. However, they did find that unbaited sticky traps still attracted female tipworm midges into the traps, and with their bright red abdomens, they’re easy to see in the traps and count. Thus, the traps are useful


for monitoring populations so growers have a better idea when to spray. She said Movento has been registered this year for use against the Cranberry Tipworm, but researchers are waiting to see how well it works on a whole-farm scale. The insecticide gets right


into the plant, shoots to roots, so the tipworm larva should suck it up. However, it’s also toxic to pollinators so can’t be used when there’s any bloom in the fields, either in crops or in weeds, to protect pollinators, she noted. It could also impact populations of


a parasitic wasp of the tipworm, which does help in their control, though not enough.


Damage done by the Cranberry Tipworm, whose female midges are easy to spot because of their bright red abdomens.


Spray times must be based on the


stages of the tipworm, yet development appears to become un- synchronized once warmer weather sets in, she said. “I think things are looking up.


We’re learning more all the time,” she added. This year, researchers are sampling


Miranda Elsby


13 fields in Richmond, Langley and Pitt Meadows, cutting different varieties and ages of plantings so estimates can be made about the number of stages and the synchronicity of development. Both the efficacy of Movento and its impact on both tipworms and their parasitoids is being studied. She advised that it’s helpful if growers have someone to sample shoots and put out traps; consultants who can help them get the newly-registered chemical on in time to be effective. She will be presenting on this pest at the Aug. 21 field day for cranberry


growers. Assisting in the tipworm work are


two students. Miranda Elsby provided some background information on the tipworm and


noted it can reduce yield by as much as 50 per cent, late in the year so it prevents the flowers and fruit from forming for the next year’s crop. In the field, she said cupped leaves


are indicative of the presence of Cranberry Tipworm, but at that point damage is often too far gone to be prevented. It is a well-established pest in the


U.S., but was not observed in B.C. cranberries until 1998. A small midge lays its eggs in the


bud of an upright shoot, goes through three stages of larval development, during which it feeds on the bud of a tender shoot, before a pupa is formed. It either overwinters in the debris


layer or emerges as an adult to continue the cycle, she explained. Monitoring involves collection of at


least 50 shoots from each field, then examining each for different stages of the pest under a microscope, she said.


Sweep netting can also be done to capture the adult, which would indicate shoots are likely being affected by the larval stage, she said. More effective and accessible monitoring methods are being explored, she added. The project work is being done by


the B.C. Cranberry Marketing Commission with funding from the Investment Agriculture Foundation.


British Columbia Berry Grower • Fall 2013 13


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