Let’s get control

The need for effective and widespread management of Queensland fruit fly (Qfly) has reached a critical level with growers across the region bracing for a challenging 2021-22 growing season, as a result of increased fruit fly pressure.

Cobram and District Fruit Growers Association president Tony Siciliano (pictured) said an alarming rise in fruit fly activity was triggered by the lingering effects of La Niña and COVID-19.“There is no doubt that Qfly will be a major problem for Victorian growers and growers in southern New South Wales and South Australia in the upcoming season. We are very much aware and bracing for that,” Mr Siciliano said.“The current situation has been exacerbated by weather conditions resulting from La Niña and the fact that COVID-19 has caused serious problems in the harvest of commercial fruit due to travel restrictions for itinerant workers.”Cobram and District Fruit Growers Association general manager Karen Abberfield said the 2020-21 season saw a significant increase in Qfly pressure across the Goulburn Murray Valley as conditions were ideal for fruit fly survival and spread, and warned the full effects of this increased activity will be seen next growing season.“We are currently faced with the situation where we have a large volume of ripe, unharvested fruit left hanging on trees and large volumes of fruit will have fallen to the ground or have been dumped after culling in the packing house,” she said.“Much of this fruit will remain there, untreated and likely to be struck by the higher-than-normal Qfly population on-site at present due to favourable weather conditions.“There is a very large and persistent Qfly population present all over Victoria and southern New South Wales and Qfly has also spread into some other regions causing severe concerns regarding exports.”Action now is critical to minimising the impact on the upcoming season, according to Ms Abberfield.“All host fruit, on the tree, on the ground or in exposed dumps, should be removed or treated so that adult Qfly cannot access egg-laying sites, and  so eggs and larvae in fruit and pupae in the ground are eradicated,” Ms Abberfield said.Higher than usual March and April rainfalls and minimum temperatures favour fruit set.This encourages the ideal fruit for fruit flies to lay their eggs in addition to the initiation, spread and proliferation of microorganisms that fruit flies feed on, resulting in stronger and more long-lived fruit flies.More warm autumn evenings allow more fruit flies to mate and produce eggs further into the autumn than usual. These conditions allow more fruit flies to survive from previous infestations and mid-autumn infestations and move into winter refuges.“As a result of these conditions we know more fruit flies than usual will survive the winter and more flies than usual will emerge from their winter refuges in late August, September and early October, which is cause for concern,” Ms Abberfield said.