Queensland Fruit Fly Outlook – October 2021

This information has been commissioned by the Goulburn Murray Valley (GMV) 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 unauthorised alterations to the text or content is not permitted.

Fruit fly activity

1. Queensland fruit fly (Qfly) trapping rates spiked in late August and early September reflecting the emergence of adult fruit fly from their winter refuges.
2. Weather outlooks for October in the Goulburn Murray Valley (GMV) favour the survival and egg-laying capacity of these fruit fly.
3. Early vigilance (looking for sting marks on fruit) and orchard hygiene (removal of unwanted fruit and fruiting plants) will reduce the impact of the new fruit fly generation.
4. fruit fly numbers will drop during October as these flies die out – leaving their eggs, larvae and pupae in the landscape to replace them.
5. The GMV fruit fly trapping grid can be used to identify likely spring hot spots, where and when fruit fly management activities can be implemented and how effective its Area Wide Management programs, including sterile insect technique (SIT), are performing.

Urban areas of the Goulburn Murray Valley

There was a peak in fruit fly trapping in August/ September. These flies were those that successfully survived the winter by sheltering in warm refuges. They are now ready to mate and start laying eggs into fruit. Ripe or ripening fruit is as risk of being infested and extra care should be taken to monitor and inspect fruit at this time of the year. These infestations will be the first 2021/2022 generation of fruit fly that will attack urban and rural fruiting plants in December through to the middle of May.

It is likely that urban fruit fly spread from urban areas, through peri-urban locations and into rural commercial orchards.

Effective control of fruit fly in urban areas will protect crops in both urban and rural locations.

Urban control methods include:

• Using traps to monitor for the presence of fruit fly
• Checking fruit for signs of fruit fly infestation:
  • Presence of sting marks
  • Presence of eggs or larvae
• Check fruiting plants, including fruiting weed plants, in the backyard, front yard, house paddock, nearby roadsides, untended land and creek banks.
• Using fruit fly control baits
• Using netting
• Removing fruit or fruiting plants before fruit ripens

Rural areas of the Goulburn Murray Valley

The September fruit fly peak recorded in urban areas of the Goulburn Murray Valley region does not occur in rural areas of the Goulburn Murray Valley except where untended evergreen fruiting plants exist or if the rural location is within about 400m of urban locations where fruit fly was present during the 2020/2021 season.

It is still important to monitor traps and fruiting plants for signs of early fruit fly incursion especially in plants that are growing away from well-managed orchards. These plants are often forgotten in the management of fruit fly:

• Feral fruiting plants growing on creek banks, roadside reserves, property front yards, untended and abandoned orchards and fruiting plants used as street trees and hedges/ boundary plants (these plants include peaches, apples, blackberries, rosehips, prickly pear.)

Weather outlook and fruit fly

The Bureau of Meteorology forecasts that October 2021 will be a warmer and wetter month than on average for October. For the majority of the GMV, there is a 70% to 75% chance that October will be wetter than normal (25mm to 50mm). The region of the GMV along the Murray River from Mathoura to Howlong, including Cobram, has a higher chance (75% to 80%) of increased rainfall. There is a 55% to 60% chance of higher maximum temperatures (21˚C to 24˚C) and a 70% to 80% chance of higher minimum temperatures (6˚C to 9˚C) in the Goulburn Murray Valley.

These conditions favour fruiting of fruit fly host fruit such as loquats and apricots, the spread of fruit fly food such as bacteria, fungi and yeasts, as well as encouraging the growth of fruit fly eggs, larva and pupae and the lengthening and, therefore, fecundity of adult fruit fly.

Hot spots to monitor

The Goulburn Murray Valley regional trapping grid was established to monitor fruit fly activity across the region. Despite the August/September spike, numbers are relatively low when compared with previous years, however a number of locations have registered more fruit fly than others.

Extra vigilance is required in the flowing locations:

• Mooroopna
• Kyabram
• Tatura
• Violet Town
• Numurkah
• Merrigum
• Rochester

It is recommended that residents of these towns and orchardists situated within about 400m of the edges of these towns be on the look-out for fruit fly.

Goulburn Murray Valley Fruit Fly Project

For assistance in managing fruit fly, contact the Project Coordinator at the GMV Fruit Fly Office by phoning (03) 5871 9222 or emailing gmvfruitfly@moira.vic.gov.au. For more information on fruit fly control and area wide management strategies visit www.fruitflycontrol.com.au

This report was produced by Andrew Jessup, Janren Consulting Pty Ltd in conjunction with analysis of regional trapping data supplied by the GMV Fruit Fly Area Wide Management Project.