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Fruit Flies in the GMV – Outlook for March 2018

April 3, 2018

This information has been commissioned by the Goulburn Murray Valley Regional Fruit Fly Project and is funded by the Victorian Government’s Managing Fruit Fly Regional Grants Program. Use of this material in its complete and original format, acknowledging its source, is permitted, however, any unauthorised alterations to the text or content is not permitted.

In May 2017 the Victorian Government and Horticulture Innovation Australia funded the deployment of over 300 male-targeting Queensland QFF (QFF) traps in and around 21 towns between Strathbogie and Cobram in the Goulburn Murray Valley (GMV).

Traps were placed in rural and urban areas. Each trap contained a male QFF attractant (cuelure) and a pesticide (malathion). They are checked every week from October to March.

These traps do not attract female QFF. They detect the presence, or confirm absence of, QFF populations and they measure changes in QFF populations over time.

The trapping program is a component of a larger project with the objective of reducing populations of QFF in the GMV to a point where production, productivity and export earnings are not restricted.

COMMUNITY

Current situation – end of February 2018
QFF adults are still being trapped in urban areas of the GMV. This means that, right now, the GMV QFF population is present as a mixture of adults, eggs, larvae and pupae. The weather is suitable for growth and maturation of QFF and there are many ripe and ripening fruit and vegetables that QFF will infest easily. These fruits exist in home gardens, orchards, untended properties, roadsides, channel banks and bushland.

There was a downward trend in the numbers of QFF trapped in the GMV during early February, but this trend reversed over the latter part of February and the first week of March. An average of over three flies per trap per week in traps placed in urban areas for the first week of March is a little less than the region experienced in mid-December 2017 (nearly four flies per trap per week) but, still, is a disturbingly high catch rate.

The community needs to keep picking and destroying all fruit, including those on the ground, that are not going to be used and removing unwanted QFF host plants. This action will reduce QFF in our towns.

QFF outlook – March 2018

Generally, March is the natural time for QFF trap captures to decrease in urban areas. This happens mainly because of lower daily temperatures.

Don’t be fooled!

Unfortunately, it doesn’t mean that there are fewer QFF in the area – just that they are less attracted to male-targeting fruit fly traps. During March and April, QFF males and females change survival strategies from reproduction, during the warmer weather, to surviving the winter where extra protein, for both sexes, is essential.

Proteinaceous fruit fly baits and traps can be very effective when deployed at this time of year as they can remove both males and females from the landscape and assist in reducing overwintering QFF populations which, in turn, reduces QFF damage risks in the following spring and summer.

However, QFF control in urban areas during March is very important as weather conditions actually improve for QFF, with cooler days and relatively warm nights, even though QFF trap numbers decline. This situation is especially favourable for QFF if there are ripe fruits available at this time. The most likely QFF host fruits include feijoas, apples, ripe oranges, plums, late peaches.

It is extremely important to reduce the number of QFF able to lay their eggs into fruit at this time by monitoring these fruit for QFF infestations, restricting access of QFF to ripe fruit (with, for example, netting or removal and destruction of unwanted fruit or removal of unwanted fruiting plants). It is the offspring of these flies that will survive over winter and cause problems to the community and the commercial grower alike next season.

General precautions for home gardeners with fruiting plants
Home gardeners can produce good quantities of their own fruit and vegetables by keeping QFF in check and, in so doing, they will help stop QFF from spreading out of town and into commercial orchards. You should consult with local friends and neighbours to see if fruit flies are nearby. Your local Fruit Fly Co-ordinator, Agriculture Victoria staff and produce store can help with suggestions on possible options.

FARMERS

Current situation – end of February 2018
QFF trap captures in both urban and rural locations have increased over the last month. There has been an increase in QFF captures in both rural traps and urban traps.

This means that farmers who grow QFF host plants need to be checking their crops and house yard plants for signs of QFF infestation. They need to carry out preventative QFF control, such as using fruit fly baits, crop hygiene (pick up fallen fruit and harvest ripe fruit and use or destroy), crop protection (netting, approved cover sprays) and, if necessary, tree removal.

There was a downward trend in the numbers of QFF trapped in the GMV during early February, but this trend reversed over the latter part of February and the first week of March. Trap catch rates for rural trap locations are, currently, the highest since records commenced in June 2017. They are now averaging at 1.6 flies per trap per week throughout the rural areas of the GMV. This is a disturbingly high catch rate.

QFF outlook – March 2018

It is likely that QFF numbers in traps will decrease over the next couple of months in rural areas of the GMV.

Don’t be fooled! This decrease is due to cooler days and nights making male-targeted traps less attractive to QFF. QFF adults in the orchards or house yard are still there and are still active. Immature QFF – eggs and larvae in fruit and pupae in the soil – are still there ready to carry on the population into and through winter.

You can reduce the impact of QFF on fruit production next spring and summer by implementing QFF control strategies. QFF can use rural farms/ properties that have fruiting plants, and which are close to town, as “stepping stones” from urban areas to commercial orchards in summer and autumn and back again to urban areas during the autumn. Therefore, it is important that occupiers of such peri-urban gardens should follow the general precautions outlined below. By doing this they will help commercial horticultural production which is a significant provider of business for the local area.

Not all rural areas are currently at risk but those which are adjacent to urban areas will more likely be targeted by urban QFF moving out.

Particular attention should be given to fruit on feijoas, late peaches and oranges, apples and plums for QFF control. It would be very wise to treat Indian figs (prickly pears) with fruit fly baits or remove them totally as they are also a significant source of over wintering QFF.

General precautions for farmers with fruiting plants

Farmers should carry out QFF control measures right now. If QFF can be tackled now, especially by picking up and destroying fallen fruit and harvesting any fruit that’s still on the tree and processing, eating or destroying it, the QFF threat for autumn will be reduced.

Farmers can produce good quantities of their own fruit and vegetables by keeping QFF in check and, in so doing, they will help stop QFF from spreading into commercial orchards

Farmers should place male- and female-targeting fruit fly traps in their yards. They should remove unwanted fruit trees and use fruit fly control methods such as garden hygiene, fruit bagging, tree netting and fruit fly baiting. They should also consult with friends and neighbours to see if fruit flies are nearby. Your local Fruit Fly Co-ordinator, Agriculture Victoria staff and produce store can help with suggestions on possible options.

Please support the fruit tree removal program or simply remove as many unwanted fruiting plants as you can.

COMMERCIAL GROWERS

Current situation – end of February 2018
Over the last two weeks QFF trap captures in both rural and urban areas have increased significantly. Rural trap catches in the first week of March 2018 are at the highest rate (1.6 flies per trap per week) since records commenced in June 2017. Urban traps are also high (at 3.4 flies per trap per week) although slightly less than during mid-December (3.9 flies per trap per week).

This situation is serious.QFF monitoring and control are now essential jobs to ensure the safety of next season’s crops. Adult QFF and their eggs, larvae and pupae that are currently existing in the GMV will be the cause of damage to production and exports of the region’s crops next spring and summer.

Some areas within the GMV have registered above-average numbers of QFF per trap per week.

All growers should now have deployed, in their orchards, house paddocks and other positions likely to be attractive to QFF, monitoring traps which are in good condition (i.e. lures and toxicants have been replaced according to product label conditions) and have a regular trap checking schedule of at least once a week but preferably more often. Growers should also, now, be checking ripening fruit for evidence of QFF through the presence on “sting marks” on fruit. They should have a supply of baits and/or allowable pesticides for use as soon as the QFF risk is too great.

 

QFF outlook – March 2018
The bottom line is ….. over the last month, an increase in QFF numbers has occurred in both rural and urban areas of the GMV. These adults plus their eggs, larvae and pupae that are in fruit or soil right now will be the overwintering population and those flies will then be the source of infestations in spring and summer nest season.

Even though QFF trap numbers will go down over the next month or so, surviving adults and immature life stages will survive unless they are controlled.
It is very important to maintain fruit fly baiting after harvest to make sure many of these adults are killed off before they go into winter survival mode by the end of April.

It is also very important to make sure that QFF eggs and larvae are not allowed to persist in fruit or as pupae in soil. Orchard hygiene, removal and destruction of unwanted fruit and fruit trees, cover sprays need to be applied, depending on the severity of QFF as seen in fruit and traps.

Particular attention should be given to fruit on feijoas, late peaches and oranges, apples and plums for QFF control. It would be very wise to remove or treat Indian figs (prickly pears) with fruit fly baits as they are also a significant source of over wintering QFF.

General precautions for commercial growers of fruit

Right now, the GMV QFF population is present as a mixture of adults, eggs, larvae and pupae. The weather is suitable for growth and maturation of QFF and there are many ripe and ripening fruit and vegetables that QFF will infest easily. These fruits exist in home gardens, orchards, untended properties, roadsides, channel banks and bushland.

Commercial growers should carry out QFF monitoring and control measures right now.

Commercial growers should now have male- and female-targeting fruit fly traps in their house yards and orchards and set up a trap monitoring program. They should remove unwanted fruit trees and use fruit fly control methods such as orchard hygiene, baiting, cover sprays, etc. Your local Fruit Fly Co-ordinator, Agriculture Victoria staff and produce store can help with suggestions on possible options.

Please remove as many unwanted fruiting plants from your orchards, house gardens, creek and channel banks, roadsides and boundaries, as you can.

Produced by Andrew Jessup