As autumn brings cooler temperatures to parts of Western Australia where Mediterranean fruitfly, or medfly, can infest fruit, growers are reminded to watch for and guard against signs of populations increasing. “Autumn is a period when growers must remain vigilant against fruitfly, particularly if they grow apples and pears,” says the statement issued by the West Australian Department for Agriculture and Food (DAFWA). Pome fruit growers should continue to bait until at least two weeks after harvest is completed, according to the Department’s advice.
Research carried out by DAFWA indicates that medfly numbers start to rise in April, and peak in May, meaning now is the time they may take hold if given the opportunity. Senior research officer with DAFWA, Dr Sonya Broughton, said that studies carried out indicated medfly larvae can survive the winter in apples, and that adults can use citrus fruit as a shelter during the winter months. “Studies of what fruits are available to Medfly throughout the year have shown that adults also use citrus as an overwintering shelter,” she said. “Strict orchard hygiene coupled with late foliage baiting is necessary during autumn as these flies are the source of the following season’s early population.”
Compliance does not appear to be a major issue for growers, who monitor medfly numbers and do not have to resort to harsh chemicals. “We are very fortunate to have an extremely low level of Medfly cases here at the orchard. Throughout the year we follow a very strict regime to monitor for Medfly and keep records of our findings,” says Suzie Ellis-Jones, of Moora Citrus. “We work closely with the department of Agriculture and make sure that our traps are up to date. At this point in time we are fortunate to not have to use any pesticides on the trees or fruit.”
The threat of medfly population increase is already factored into the orchard’s workplan, so does not bring with it any increased costs, and most Moora Citrus do not expect to lose any fruit to medfly, according to Ms Ellis-Jones.