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Time to clean up Queensland fruit fly

North Coast Local Land Services Agricultural Advisory team have provided advice to landholders who grow fruit and vegetables to help minimise the spread of Queensland fruit fly Bactrocera tryoni.

Julie Dart, Senior Local Land Services Officer said “Queensland fruit fly is a major pest of fruits and vegetables locally, both for home gardeners and commercial fruit and vegetable growers.

“It is important that steps are taken to minimise the build-up of numbers through good sanitation and Autumn is an excellent time to get rid of waste fruit and vegetables.

“If you are getting rotten patches and small white maggots in your produce, you have a fruit fly problem.” Julie said.

Whilst the battle may have been lost to fruit flies in backyard crops this summer, all landholders with fruit trees and vines and some fruiting vegetables such as tomatoes, chillies and eggplants should be aware that they have a responsibility to manage pests and diseases.

Queensland fruit fly is a native insect that traditionally lived in rainforests, but has adapted to cultivated fruiting crops.  Queensland fruit flies have a very short lifecycle of 28 days in the summer, and can attack crops several times a year.

Female flies “sting” ripening fruit to lay their eggs, the eggs then hatch into maggots which feed on the fruit which then drops to the ground as it becomes rotten.  The maggots then bury themselves into the soil to pupate and later emerge as adult flies to mate and the cycle continues.

Julie continued, “Unfortunately with our mild subtropical climate, conditions do not get cold enough to kill off enough of the fly population over winter, which leaves crops vulnerable to the pest in early spring.”

Queensland fruit flies attack actively growing fruit, so if you don’t plan to eat it or share it, the rule is to destroy it and this should be applied year round. Steps can then be taken to protect new crops with protein baiting, cover sprays or exclusion bags.

Don’t forget that some flowering ornamental trees such as crab apples, guavas and loquats also have fruit that is attacked by fruit flies.  The fruit on these trees needs to be considered in the backyard management process.

For small amounts of unwanted and fallen fruit, seal it up in a black plastic garbage bag and leave in a sunny spot for a couple of days to cook and kill the maggots.  Afterwards, fruit can be put into the Green-waste bin (without the bag), to go into compost.

For large quantities of fruit, such as home and commercial orchards, fruit can be dropped on to the ground and then chopped up with a mower.  This will help the fruit waste break down quickly and will also return nutrients to the soil.

Consider removing unwanted fruit trees, or strip fruits off each year before they can ripen.  Tenants in rental properties should seek permission from their landlord before removing unwanted fruit trees.

“Doing your bit in the backyard helps our local fruit and vegetable growers use less insect sprays on the fruit and vegetables grown in our region, which is a good outcome for everyone.” Julie concluded.

For a fact sheet on fruit fly control methods in the home garden, contact Julie Dart at North Coast Local Land Services on 6659 9406 or by email julie.dart@lls.nsw.gov.au.

Media contact:           Julie Dart, Senior Land Services Officer, Phone 6659 9406

Photo captions:         Queensland fruit fly