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Fruit Flies in the GMV – Outlook for May 2018

May 7, 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 fruit fly (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 May to detect the presence, or confirm absence of, QFF populations and to measure changes in QFF populations over time.

The QFF 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 – May 2018

WARNING EXTENDED SUMMER MEANS EXTENDED FRUIT FLY SEASON…

  • The more QFF adults, eggs, larvae and pupae present during April/May the more will survive winter
  • The more QFF that survive winter the bigger the problem in next season’s crops

QFF adults are still being trapped in urban areas of the GMV. We trapped more QFF in the second week of April than in any week since recording commenced in May 2017.

Some unmanaged ripe fruit that are present right now will contain QFF eggs and larvae and there will be QFF pupae in the soil under some plants that have carried ripe infested fruit recently.

Normally, at this time of year the weather cools down so much that numbers of trapped QFF decrease – and keep going down from now until next spring. However, the region is experiencing an extended summer. Currently, the weather is still suitable for growth and maturation of QFF and there are still many ripe and ripening fruit and vegetables around that QFF will infest easily. These fruits exist in home gardens, orchards, untended properties, roadsides, channel banks and bushland.

A look at March/April weather for 2018 reveals that temperatures are warmer than is normally the case (compared with the same period during 2016 and 2017). Temperatures have been relatively stable and have not yet commenced their downward trend.

Over the whole GMV, the average number of adult QFF in each trap increased. However, this increase was more dominant in rural traps. During the second week of April, rural traps caught more QFF than they did throughout 2017 and early 2018. On the other hand, traps in urban areas registered much lower numbers than they did during the spring and early summer QFF peaks.

We need 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. Those actions will reduce QFF in our towns.

QFF outlook – May 2018

Generally, March and early April is the natural time for QFF trap captures to decrease in urban areas due to lower daily temperatures. This is not yet happening in 2018. Over the last 6 weeks average temperatures have remained stable rather than decreasing. This means that traps are now catching more QFF than ever.

This situation is especially favourable for QFF survival into next season because, right now, there are ripe fruits available. The most likely QFF host fruits include feijoas, apples, ripe oranges, plums, late peaches.

It is extremely important to reduce the number of QFF adults and stop them from laying their eggs into fruit. Gardeners should monitor these fruit for QFF infestations and restrict 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 should consult with local friends and neighbours to see if fruit flies are nearby. Contact your Fruit Fly Coordinator for suggestions on management practices.

FARMERS

Current situation – May 2018

WARNING‼ EXTENDED SUMMER MEANS EXTENDED FRUIT FLY SEASON…

  • The more QFF adults, eggs, larvae and pupae present during April/May the more will survive winter
  • The more QFF that survive winter the bigger the problem in next season’s crops

QFF adults are still being trapped in urban areas of the GMV. We trapped more QFF in the second week of April than in any week since recording commenced in May 2017.

QFF trap captures in both urban and rural locations have increased over the last two weeks but the rate of QFF caught per trap in rural traps is twice that of urban traps.

If unmanaged plants with ripe or nearly ripe fruit fruited within the last month there will be QFF eggs and larvae in fruit that is still on the tree or on the ground. There will be QFF pupae in the soil beneath these plants.

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. If poultry can be run under fruiting trees, or trees that have recently finished fruiting, much of the QFF infestation will be destroyed.

QFF outlook – May 2018

Even though the GMV is currently experiencing an extended summer, QFF numbers in traps will decrease over the next couple of months in rural areas of the GMV. This is due to cooler days and nights making male-targeted traps less attractive to QFF.

However, QFF adults are still in orchards and house yards and are still active. Immature QFF – eggs and larvae in fruit and pupae in the soil – could be present, too, and if not controlled will allow the current QFF population to persist into and through winter and cause problems next season.

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

All farmers should continue 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 the rest of autumn, as well as next season, 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-targeting 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. Running poultry or other stock through orchards will also clean up QFF to a significant extent.

Farmers 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 – May 2018

WARNING‼ EXTENDED SUMMER MEANS EXTENDED FRUIT FLY SEASON…

  • The more QFF adults, eggs, larvae and pupae present during April/May the more will survive winter
  • The more QFF that survive winter the bigger the problem in next season’s crops

Over the last two weeks QFF trap captures in both rural and urban areas have increased. We trapped more QFF in the second week of April than in any week since recording commenced in May 2017.

The rate of QFF caught per trap in rural traps is twice that of urban traps.

This is unusual for this time of year. Fly numbers should be decreasing due to cooler temperatures, but they are not. This is because average daily temperatures have been stable and QFF are staying very active – as adults, eggs and larvae in fruit and pupae in the soil.

The situation is serious. We must bring QFF numbers down before winter so that the numbers of adult QFF surviving through the winter is minimised. It is these overwintering adults that constitute next season’s parental population. QFF monitoring and control are now essential jobs to ensure the safety of next season’s crops.

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 of “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 – May 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 next 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. If possible, running stock such as chickens or sheep through harvested orchards or areas where unwanted fruit is present will reduce QFF populations significantly.

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-targeting 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 Fruit Fly Co-ordinator can help with suggestions on management practices.

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

For assistance in managing QFF contact the GMV Fruit Fly Coordinator, Ross Abberfield by phoning (03) 58719222 or emailing gmvfruitfly@moira.vic.gov.au

This report was produced by Andrew Jessup and incorporates an analysis of regional trapping data supplied by the GMV Fruit Fly Project.