Typically, cover spraying is dispersed over the entirety of  a crop For large-scale farm crops, this is done via large machinery that blows fine droplets throughout a tree’s canopy or through an overhead boom spray for low crops.

Traditionally systemic insecticides such as dimethoate and fenthion (trade names Rogor and Lebaycid) were used in this way and were able to kill fruit flies present in the orchard. This also had a residual effect that would kill any eggs or larvae either in fruit or laid into fruit after the treatment.

However, many previously permitted uses of these sprays have since been withdrawn.

There is a range of other chemical products that can currently be applied via cover sprays, such as clothianidin, trichlorfon, and chlorpyrifos, with other chemicals being trialled by researchers and state departments of agriculture. For the latest information on chemicals that are registered for fruit fly control, and the particular cropping situations, you should consult the Public Chemical Registration Information System (PubCRIS) or your local chemical supply company or garden store.

For home gardens alternative approaches such as Spinosad based insecticides can be used.

Before you implement cover spray methods, consider whether you live in an area prone to fruit fly attacks, and whether you have the time to implement this strategy into your garden (as spraying needs to be maintained diligently).

Speaking to local experts in your area is always recommended before starting your fruit fly management plan.

• Effectiveness of the cover spray product you use.
• Usage in combination with other control methods such as sanitation and baiting.
• Timing of the spray application (best before fruit fly have attacked)
• Adequacy of spray coverage on to plant parts.
• Managing any off target impacts, such as injury or damage to other plants, animals, environment or property.

Video: Control of Mediterranean fruit fly in WA backyards—Department of Agriculture and Food WA

Mediterranean fruit fly—Department of Agriculture and Food WA

• Completely protects your crop so that you can harvest it larvae (maggot) free.
• Allows produce to ripen as normal on the tree or plant.
• Requires a once only application of exclusion products over your crop.
• Can help protect your crop from other insect pests, as well as possums and birds.
• Some exclusion products can be reused from year to year.
• Relatively low cost and easy to use when compared to cover spraying.

Before you implement exclusion control methods in your garden, check the criteria listed below to make sure it’s right for you.

• You live in a fruit fly prone area, particularly in highly infested areas.
• You want to use an effective, organic method without the use of chemicals.
• You need your produce to ripen on the plant as it is unsuited to being picked green.
• You are willing and able to spend time in the garden placing barriers on plants and monitoring fruit for ripeness.
• You have had only limited success with other control methods such as cover spraying and baiting.
• You want the option of either making your own or buying exclusion products.

While exclusion is a strong first line of defence against fruit flies, there are several factors that can affect success, as detailed below.

• Integrity of exclusion barriers, for example well secured, and free from tears and gaps.
• Timing of the placement of barriers over your fruit and vegetables.
• Usage in combination with other control methods such as sanitation and pruning.
• Removal of any infested fruit if barriers are placed on plants late in the season.

Before implementing exclusion control methods into your garden, you may need to reflect upon the following:

• Exclusion can be labour-intensive and time-consuming when installing, monitoring and removing barriers from plants, particularly if you are using bags and sleeves and have a big crop.
• Requires that you prune trees to a smaller size so that you can more easily install, check and remove barriers.
• Integrity of exclusion products may be damaged if are not removed at the end of the season.
• Barriers may not be aesthetically pleasing to the eye (if this a concern to you).

When it comes to exclusion prevention methods, the earlier you start the better. As soon as that first petal drops (an indication that pollination has occurred) and fruit begins to show the first signs of developing, you are ready to start putting in your fruit fly barriers.

Placing exclusion products on the plant at this time will best protect your produce, since fruit flies tend to target fruit and vegetables that are maturing or ripe. If you suspect that your produce has already been stung, then remove it before netting or bagging. Note that self-pollinated crops can be covered any time before fruit matures or ripens.

If you are feeling creative and have the option to do so, creating your own exclusion barriers can be simple and cost-effective. While homemade nets and frames may need a little more work, exclusion products, such as cloth or paper bags and sleeves, can be made relatively easily from items around the house. Regardless of what materials you use, your homemade exclusion barrier should be made to withstand all weather conditions.

Some ideas for making your own physical exclusion products are provided below.

Nets

• Nets can be made from materials such as mozzie (mosquito) nets and gauze curtain material (1.6mm good for fruit flies and most other pests). Note that gauze curtain material may deteriorate quicker when exposed to weather.
• Nets can be made from mozzie nets, cut or sewn to desired shape and size.
• Mozzie nets can be purchased from places such as textile suppliers, department stores or hardware stores – note that lace curtain material may be unsuitable as it eventually deteriorates and become unusable).
• Frames for nets can be made from materials such as electrical conduit/Polypipe (for example two inches in diameter) that does not lose its shape in the sun.
• Frames can be constructed by crossing over and securing (tie with wire) together two lengths of pipes over the tree.
• Frames can be secured in the ground by slipping end of polypipe over pickets (for example star pickets) in the ground.
  Also consider buying umbrella and gazebo nets and frames (need to cover hole at top) which may have zipper on side for easy access.

Bags and sleeves

• Bags and sleeves are generally easier to make because of the size required and materials needed. Some gardeners have been known to use brown paper lunch bags (which may get soggy when it rains); wax paper bags that are used for keeping mushrooms in; and mozzie netting cut and sewn to size.
• Sleeves can be made from materials such as mozzie netting, fly screen and gauze curtain material, also cut and sewn to desired size.
• Both bags and sleeves can be secured to the tree or plant with string, clothes pegs or tie wire.
• Netting cannot touch ripening fruit otherwise fruit flies may still be able to lay their eggs through the net.

• Potentially more produce saved from loss to fruit fly attack.
• Reduced or no effort required to control fruit flies in your garden.
• Cost savings by reduced need to control fruit flies.

• If you live in or near a fruit fly prone area.
• own your own home (renters may be able to plant smaller crop plants).
• are unable or unwilling to control fruit fly in your home garden.
• still want to grow your own produce but do not want to have to deal with fruit fly.
• are considering the removal of plants from your garden that are prone to fruit fly attack.

• Selection of plant varieties that are suited to your locality, climate, soil etc.
• Resistance level of the plant variety to fruit fly attack (may need to control fruit flies).
• Availability of other, preferred hosts for fruit flies around your garden.

• The level of fruit fly infestation in your area and nearby areas.
• Non-preferred hosts that are suited to and do well in your area.
• Whether there are other serious pests of non-preferred host plants that

When selecting non-preferred host plants for your home garden, you should generally try to choose varieties with thicker or tougher skin. This can help prevent fruit flies from being able to sting and infest produce. Your local garden centre should be able to help you find the right plant for you. You can also get advice about which varieties to plant from books and the web.

Here are some of the plants that are not highly preferred by fruit fly.

Medium risk fruit fly host fruit and veg

• Avocado (try thicker skinned varieties such as Sharwil and Haas)
• Blackberry
• Button squash
• Cashew apple
• Cherry
• Cucumber
• Custard apple (winter ripening varieties are best)
• Date
• Eggplant
• Feijoa
• Grapefruit
• Jujube
• Longan and lychee
• Mulberry
• Orange
• Passionfruit (possibly major host)
• Persimmon (varieties such as Fuyu are susceptible)
• Pomegranate
• Pumelo
• Pumpkin
• Quince
• Rockmelon Rollinia
• Sapodilla
• Strawberry
• Soursop
• Tamarillo
• Tomato (when ripe is major host)
• Walnut
• Watermelon

Low risk fruit fly host fruit and veg

• Fig
• Grapes (sometimes affected)
• Lemon and lime (avoid thin-skinned varieties like Meyer lemon (lemons are resistant when green)
• Monstera
• Olive
• Star apple (possibly major host)
• Tangelo

Non hosts include

• Choko
• Coffee
• Jackfruit (if undamaged)
• Longan
• Mangosteen
• Pineapple
• Rambutan (if undamaged)

Other non-preferred hosts include:

• Blueberry (is sometimes affected)
• Bananas (resistant to attack when green, otherwise high risk)
• Grumichama
• Mango (some resistance to Mediterranean fruit fly, but prime Queensland fruit fly host)
• Kiwi fruit*
• Nashi Pears (sometimes affected)*
• Mulberry (sometimes affected)*

Source: Adapted from Horticultural Policy Council (1991), The impact of fruit flies on Australian horticulture. HPC Industry Report No. 3, the Council

Before you implement sanitation methods in your garden, check the criteria listed below to make sure it’s right for you.

• You live in an area prone to fruit fly attack.
• You are physically able and willing to undertake the work while your crops are fruiting.
• You prefer to use low impact, organic approaches to fruit fly control.
• You grow a surplus of fruit that falls to the ground or is not harvested.
• You want to help prevent fruit fly from establishing in your garden in areas where it does not occur.

• It Helps prevent and break the fruit fly breeding cycle in your garden.
• A relatively cheap and easy to do.
• It may also help eliminate the sources of fruit fly infestations for neighbours and near-by fruit production areas.

• If you live in an area prone to fruit fly attack.
• Are physically able and willing to undertake the work while your crops are fruiting.
• Prefer to use low impact, organic approaches to fruit fly control.
• Grow a surplus of fruit that falls to the ground or is not harvested.
• Want to help prevent fruit fly from establishing in your garden in areas where it does not occur.

• Usage of sanitation in combination with other fruit fly control methods (note that if you live in an area that is free from fruit fly, practicing sanitation to prevent fruit fly infestations may be sufficient alone).
• Usage of techniques that properly destroy infested fruit and vegetables.
• Diligence to maintain the practice.

• While trees and plants are fruiting, you will need to collect any fallen fruit and unharvested rotting fruit on a daily basis.
• Sanitation can require a lot of physical labour, particularly if you have a lot of crop plants in your garden.
• Bags of baked/solarised fruit in your bin can be smelly and messy.

Fallen and rotten fruit and vegetables should be removed and disposed of, including any fruit from the tree with dimples or weeping clear sap. While there are many ways to destroy collected fruit, to make sure it is done properly, use the following technique:

• Place fruit inside strong plastic bags (double bag if necessary) and seal tightly.
• Expose the bag to the sun (solarising) for at least three days; or seven days if temperatures are below 30 degrees Celsius.
• Dispose of bags in the normal household rubbish collection, do not compost.
• Alternatively, you can collect fallen fruit in a plastic bag and place it into a freezer for two days.
• Do not dispose of unwanted fruit and vegetables in compost piles or worm farms, instead, place it directly into the household rubbish collection.

Fallen and rotten fruit should be picked up on a daily basis to prevent it from being infested and allow the breeding cycle to continue.