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Sunday
Feb052012

The fruit fly menace

There’s little more disappointing than opening a gorgeous fruit to find it infested with fruit fly maggots! Fruit fly is a serious agricultural pest in our part of the world, and summer is when they’re in full swing. There’s over 250 species of fruit fly in Australia, but thankfully only a handful damage food crops. The worst offender in our region is the Queensland fruit fly.    


For the most part, our strategy for dealing with fruit fly is to grow trees that have a high resistance to fruit fly in our climate. Bananas, paw paw, cherimoyas, babaco, Atherton raspberry and many more fruit trees generally don’t get fruit fly in our area (for a full list see details in our Illawarra Edible Garden Guide!). We find in our coastal climate the trees fruit fly love the most are the stonefruits – plums, peaches, nectarines and apricots. Guavas and fejoas are also quite susceptible. Our neighbours have a peach tree which is badly infested each year, with all the fruit ruined by fruit fly.

Stonefruit are just delicious, and grow so well in our climate. So the way we manage to grow them organically is by keeping dwarf varieties in a pot. This way it’s easy to bag individual fruit with fruit fly exclusion bags when they are very young. As our trees grow, next summer we plan on netting the whole tree in the pot, to prevent fruit fly getting in. Netting trees that are growing in the garden, rather than being kept to dwarf size in a pot, is much more challenging and high maintenance – hence off the cards for us in our low maintenance garden! In the same way, rather than grow large tomatoes which can be highly susceptible to fruit fly, we grow small cherry tomatoes in the veggie patch as they’re much more resistant and generally don’t require bagging for protection.

The Victorian Department of Primary Industries recommends to minimise fruit fly infestations that backyard gardeners: 

  • Prune trees to a height which makes fruit picking easy
  • Remove fruit as it ripens
  • Don’t place infected fruit directly in your compost bin, worm farm or garbage bin
  • Collect and dispose of infected fallen fruit by sealing fruit in a bag and leaving it in the sun for 5-7 days or placing it in the freezer.
  • Remove unwanted trees from your garden (and we would add, replace them with fruit trees that are not so susceptible to fruit fly!) 

There’s also another good website at http://preventfruitfly.com.au/ which has info for backyard gardeners about fruit fly and control strategies.

We usually dispose of any infested fruits by freezing them. After freezing we add them to our compost bin.

Do you get fruit fly where you are? How do you manage gardening organically with this cheeky pest?

Reader Comments (6)

This year a few beautiful tomato plants popped up in the garden, with really big fruit. So far, I've had no fruit fly. I decided to try bagging the trusses with some bags I bought quite cheaply off ebay. So far, so good. We're enjoying not buying tomatoes! I'm in the same area as you, Happy Earth. Have you noticed a particular time of year that fruit fly are most active in our region? Has it been different this year with all the rain? I've only just started observing the growing patterns in my garden, and have never been successful with big tomatoes before. Thanks for the links, I'm looking forward to reading through the info :)
February 5, 2012 | Unregistered Commentersribee
Great to hear you have had such success with your big tomotoes Mandy! It is so lovely to be able to enjoy them fresh from the garden. It does seem to vary when fruit fly are at their worst. We find anytime apart from winter and early spring they can be bad. You tend to notice them more or less depending on what you're growing also. Stonefruit are often the worst hit, and our neighbours peach tree dropped all it's fruit in late December/early Jan as they had been ruined with fruit fly. We recall a few years back the end of summer being really bad and they were even getting into cherry tomatoes and capsicum in our garden, which are usually not so susceptible - the weather would play a role too, and as you say it's been so wet this summer, it would be interesting to know if/what affect that has had on them!
February 8, 2012 | Registered CommenterHappyEarth
I live in Wombarra and haven't noticed any fruit fly, though I've got big tomatoes and guavas fruiting. Next door there's a big old nectarine tree that seems to stay fruit fly free (though the birds are another matter). Perhaps I'm just living in a little pocket they haven't found their way to. Any ideas on why I'm not seeing them (I know Wombarra has much higher rainfall than the coastal plain)? I've planted peaches and apricots but they haven't fruited yet. I'm hoping that by bagging fruit most likely to attract 'em, the slightly less prone fruit won't be enough of an incentive to bring on a local population!
February 28, 2012 | Unregistered CommenterJess
Lucky you Jess ... like you say maybe they just haven't found their way to your little pocket yet :)
February 28, 2012 | Registered CommenterHappyEarth
I've had excellent success using Organza bags bought off EBay for a few cents each. You can buy 100 large bags for less than $30 delivered. They come with their own drawstring and can be used over several years on successive crops. I have particularly good success with my Nagasakiwase loquat tree that produces bunches of fruit on the tips of it's branches. The large 12cm by 160cm organza bag covers the whole bunch of fruit with one bag after thining. Once the bag has been placed over the fruit cluster I know those fruit are safe till the day they are at their most perfect state of ripeness. A perfectly ripe loquat free from FF must rival the most delicious fruit on the planet. A bonus is the tree looks very pretty with all those beautiful colourful looking bags hanging off them everywhere. I prefer the plain white colour myself.
July 24, 2012 | Unregistered CommenterJohn Mc
We are on the Sunshine Coast in Qld and have tropical peaches growing, last year the fruit flies ruined the entire crop, it was heart breaking. This season we netted the trees (which are dwarf varieties) with fly resistant nets. What a fantastic result, each piece of fruit can stay on the tree until it's ready to fall off in your hand and the taste is divine. We have never grown peaches before, it is so exciting each morning to go down and pick what is ripe and eat it that day.
November 28, 2013 | Unregistered CommenterLana

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