MAKE no mistake – Fruit fly infestations have now been identified at Moyston, Rainbow, Hopetoun, Boort, Swan Hill, Merton, Benalla, Langwarrin, Wodonga - if you grow fruit or vegetables - you are at risk.

This is of enormous concern - it affects everyone - from those of us who grow fruit and vegetables for our own use but also our horticultural industry as a whole.

Let’s be clear - we have around 5000 horticulture producers in Victoria, who employ approximately 11,000 workers.

The horticulture industry is worth over $3 billion to our economy, and exports are worth $1.6 billion.

At least $1 billion of those exported fruits and vegetables, are susceptible to fruit fly.

2019-2020 was our biggest year for fruit exports increasing by $84 million (10 per cent) to be valued at $904 million in 2019-20. China was the major market for Victorian horticultural exports with a total value of $646 million.

Table grapes recorded the largest growth in export value, increasing by $59 million (12 per cent) to a record $562 million. Export volumes increased by four per cent.

The value of citrus and stone fruit exports increased by nine per cent and four per cent respectively.

Over 100 fruit and vegetables are confirmed hosts of fruit fly meaning more than three quarters of Australian fruit and vegetable exports are susceptible to infestation.

There are a number of species of fruit fly - but the ones of most concern are the Queensland fruit fly which is now prevalent in Victoria and spreading - and the Mediterranean fruit fly (Med Fly). At this point, Med Fly is established in Western Australia and is under eradication in South Australia.

Protein and sugar sources are required for sexual maturation of the fruit fly and eggs after mating. Approximately, two days after mating the female can lay dozens of eggs into ripening fruit - still on the vine/tree. The eggs hatch and feed within the ripening fruit. A single adult female can lay up two thousand eggs in one lifetime.

FRUIT FLY CONTROL

Climate and environment govern the rate of fruit fly activity. This includes temperature, moisture levels and fruit type which will all impact the fruit fly’s behaviour, so it’s important to think about where you live and the season and prevalent conditions as these will guide your control strategy.

Spring generally sees an increase in both size and activity of fruit fly. In early spring, overwintering adult flies become active and female flies will be looking for a source of protein which is needed for their eggs to develop.

By late spring, fruit fly may have laid eggs in some early ripening fruit and from this point onwards the larvae will develop, and the fruit fly population will start to increase.

The main measures to use in early spring are fruit fly monitoring traps to identify when adult flies are first active. Direct control measures such as protein bait sprays and traps. Starting these control actions too late will allow fruit fly populations to build up rapidly.

Install traps in your vineyard (Figure 1). There are several commercial traps available. Most traps have a plastic pot containing a lure to attract the Fruit fly plus a toxicant that kills flies once they enter the trap.

Traps generally require servicing every few weeks (i.e. clean, recharge with new lures/ pesticides). Follow label instructions.

Insect proof netting can be draped over trees and other crops and supported by a frame - and should be put up after pollination has occurred. Warning though - any fruit that touches the netting is still exposed to fruit fly infestation.

There are a range of fruit fly baits and traps available and while these are easier to use, they need to be applied and maintained before fruit starts to ripen.

Clean up fallen or unharvested fruits and vegetables. Placing these into plastic bags and leaving them in the sun (solarising) for 5-7 days will effectively cook the fruit and kill any fruit fly larvae inside. Small quantities of fruit can also be microwaved.

Fruit should not be placed directly in the compost as this will not kill fruit fly eggs or larvae. Also, be aware that any old and abandoned fruit trees can be a breeding ground for fruit fly - and if possible, should be removed.

Winter is time to prune your trees and is a good time to ensure your fruit trees are not too tall to harvest (fruit you cannot reach could be a home for fruit flies).

Traps should be installed well before harvest i.e. six to eight weeks before the harvest date and checked weekly until two to three weeks after harvest to detect any Fruit fly that remain after the crop has been harvested.

Place monitoring traps within the shade of the canopy, avoiding direct sun or areas that get very hot. Use a network of traps - not just one and check them regularly.

Any infestations must be reported to Agriculture Victoria.

Be vigilant - they are spreading.

MAKE YOUR OWN QUEENSLAND FRUIT FLY TRAP

You can make your own traps using an empty soft-drink bottle and lid and homemade bait. Note that these traps can also attract insects that are good for your garden.

In an empty soft-drink bottle, cut three holes about the size of a 10-cent piece, 10cm from the top.

Add the bait mixture to the bottle. Pour in 1 cup of 100 per cent fruit juice (including pulp) and 1 tablespoon of cloudy ammonia (or wheelie bin cleaner).

Tie a string around the neck of the bottle and hang it from the tree in the shade, 1m to 1.5m off the ground.

The mixture can last up to 3 weeks but should be changed weekly for best results.

Another one that has been shared with me is to use Apple Cider Vinegar with a few drops of dish washing liquid.

Many of us take great pride in delivering home grown food to our dining tables - so let’s be vigilant.