MONTHLY FRUIT FLY TRENDS REPORT – WK 1 + WK 2 JANUARY 2018

- Toolamba to Cobram

Jessup

IK Caldwell, with funding from the State Government of Victoria and Horticulture Innovation Australia, has deployed over 300 male-targeting Queensland fruit fly (Qff) traps in and around 21 towns between Toolamba and Cobram. Traps are set out in rural and urban areas in this area. Each trap contains a male Qff attractant (cuelure) and a pesticide (malathion). IK Caldwell representatives check these traps every week from October to March. These traps are recharged with new lures and toxicants every three months.

These traps do not attract female Qff but are used to detect the presence, or confirm absence, of Qff populations and to gauge changes in Qff populations over time.

The Qff trapping program is a component of a larger project which has objective of reducing populations of Qff in the Goulburn Murray Valley region of Victoria to a point where production, productivity and export earnings are not restricted.

Towns that are trapped currently are:

·         Ardmona

·         Bunbartha

·         Cobram rural

·         Cobram urban

·         Grahamvale

·         Invergordon

·         Kyabram rural

·         Kyabram urban

·         Merrigum

·         Mooroopna

·         Orrvale

·         Shepparton East

·         Shepparton rural

·         Shepparton urban

·         Tatura rural

·         Tatura urban

·         Toolamba

·         Undera

  1. SUMMARY FOR HOME GARDENERS – WEEK ONE AND WEEK TWO JANUARY 2018

In the first two weeks of January 2018, IKC traps in all trapped regions of the GMV registered captures of male Queensland fruit flies similar to, or fewer than, captures made in the last two weeks of December 2017.

At present, numbers of males trapped are in decline but, unfortunately, at this time of year, flies are now present in all life stages – from eggs and larvae in fruit, through pupae in the soil to immature adult flies that are not attracted to traps to mature adult flies that are.

Consequently, gardeners are warned this decrease in numbers masks the real situation.

Anti-fruit fly activities, such as early removal of fruit, removal of host fruit plants, fruit fly baiting and use of exclusion netting if they had been implemented in a timely manner may have delayed or even quashed this Qff population build-up.

Therefore, from now on, with proper and timely hygiene, attempts should be made to control Qff in the home garden. This task is made easier if all neighbours work together on it.

IMPORTANT: Vigilance from now on is essential. The large upsurge seen in December, i.e. the first generation Qff is now dying out but has left very large numbers of eggs, larvae, pupae and immature adult flies in towns and gardens of the GMV. Garden hygiene is important. If these fruit, or their parent plants, can be found and disposed of, or treated adequately then it may be possible to reduce the impact of Qff in our region. 

It is recommended that householders deploy male- and female-targeting fruit fly traps. They should take advantage of offers to remove unwanted trees and consider future fruit fly control methods such as home garden hygiene, fruit bagging, tree netting and fruit fly baiting. They should also consult with local friends and neighbours to see if fruit flies are nearby. Your local Fruit Fly Co-ordinator can help with suggestions on possible options.

  1. SUMMARY FOR FARMERS – WEEK ONE AND WEEK TWO JANUARY 2018

After winter 2017, trapped fly numbers increased during September and October 2017 then declined during November 2017 but surged explosively during December 2017. In the first two weeks of January 2018, captures of male Queensland fruit flies similar to, or fewer than, captures made in the last two weeks of December 2017. The overall trap catch was about two-thirds of the late December catch.

Again, most Qff trapped during the first 2 weeks of January occurred in traps located within, or on the edge of, urban areas but numbers increased over this period in all locations, including rural areas. No regions recorded as many flies at this time as in early December.

Even though numbers are down almost all over the GMV it has to be remembered that numbers were very high during early December. This means that although numbers are in decline at this time of year, the weather is perfect for flies to now be present in all life stages – from eggs and larvae in fruit, through pupae in the soil to immature adult flies that are not attracted to traps to mature adult flies that are.

Consequently, farmers are warned this decrease in numbers masks the real situation.

Because fly numbers increased during early December and have laid their eggs soon thereafter, farmers with fruit trees in Ardmona, Bunbartha, Orrvale, Toolamba, Undera, Tatura, Merrigum, Kyabram and Mooroopna rural areas as well as those who live close to the urban areas within the GMV should have commenced fruit fly trapping and keep an eye on ripening fruit for fruit fly sting marks.

Weekly fruit fly baiting is recommended for farmers with fruit trees from 6 to 8 weeks prior to harvest, or sooner.

IMPORTANT: Vigilance from now on is essential. The large upsurge seen in December, i.e. the first generation Qff is now dying out but has left very large numbers of eggs, larvae, pupae and immature adult flies in towns and gardens of the GMV. Orchard hygiene is important. If these fruit, or their parent plants, can be found and disposed of, or treated adequately then it may be possible to reduce the impact of Qff in our region. 

Farmers should remove unwanted fruit fly host plants from their house paddock, along creek banks, on roadsides near their farm and other areas. If their farm had fruit fly problems last season they should consider future fruit fly control methods such as orchard hygiene and fruit fly baiting, placement of more traps for more accurate detection of fruit fly population incursions and purchase of approved pesticides and fruit fly baits. They should also consult with neighbours to see if fruit flies are nearby. Your local Fruit Fly Co-ordinator can help with suggestions on possible options.

  1. SUMMARY FOR GROWERS – WEEK ONE AND WEEK TWO JANUARY 2018

Following the explosive increase in numbers of male Queensland fruit flies trapped in the GMV during early December in both urban and rural areas the first two weeks of January have registered a decrease in trap numbers – 448 to 350. This does not indicate a reduction in the fruit fly population. What’s happening now is that the first generation of Qff that surged in early December is now dying out. However, as the weather is now quite optimal for Qff survival, it is likely that the first generation Qff have found mates and laid masses of eggs in any ripe or ripening fruit that is available. Qff is now present in large numbers throughout the region as a mixture of eggs and larvae in fruit, pupae in the soil, immature adults which are not attracted to traps and mature adults that are.

Commercial growers of fruit fly host plants should now have Qff management strategies set in place – either ready to implement as soon as monitoring traps show an increase in Qff of have already commenced a weekly baiting program in anticipation of harvest within 6 to 8 weeks, if appropriate for their crop. Keep in mind that fruit trees planted in house paddocks are also very susceptible to fruit fly infestations which often go unnoticed and, therefore, untreated.

Most Qff trapped during early January occurred in traps located within, or on the edge of, urban areas. Relatively few Qff were trapped in rural and small-town areas of the GMV. By and large, numbers decreased, or stayed the same, over this period in all locations. There were 54 trap sites that registered ≥1 fly/trap/week (Table 2). Of these, 38 sites were within urban areas (11 sites within Shepparton urban, 4 in Tatura urban, 3 in Kyabram urban and 20 in Cobram urban).

Again, Mooroopna, a mostly rural location should be watched closely. Mooroopna (as well as Shepparton urban) defied the general decline in captures registering 52 flies (as compared with 66 in late December).

Merrigum, also mostly rural, registered a decline with 6 flies from 11 traps – a significant decrease from the early December count of 20 flies.

Tatura rural traps declined from a total of 13 flies in 17 traps to 2 flies in that period.

For the first time, Grahamvale registered with no decrease in trap numbers – also defying the downward trend – with 5 flies found in 17 traps (5 flies were found during late December and 4 in early December).

All urban areas registered fewer flies in early January than late December except for Tatura urban which saw an increase:

  • Cobram urban area (with 100 flies from 33 traps in early January, compared with 125 in late December),
  • Shepparton urban (with 83 flies from 24 traps [early Jan] cf 84 [late Dec]),
  • Kyabram urban (with 41 flies from 7 traps [early Jan] cf 105 [late Dec]),
  • Tatura urban (with 69 flies from 30 traps [early Jan] cf 19 [late Dec]).

IMPORTANT: Vigilance from now on is essential. The large upsurge seen in December, i.e. the first generation Qff is now dying out but has left very large numbers of eggs, larvae, pupae and immature adult flies in towns and gardens of the GMV. Orchard hygiene is important. If these fruit, or their parent plants, can be found and disposed of, or treated adequately then it may be possible to reduce the impact of Qff in our region. 

Farmers should remove unwanted fruit fly host plants from their house paddock, along creek banks, on roadsides near their farm and other areas. If their farm, or next door’s, had fruit fly problems last season they should consider future fruit fly control methods such as orchard hygiene and fruit fly baiting, placement of more traps for more accurate detection of fruit fly population incursions and purchase of approved pesticides and fruit fly baits. They should also consult with neighbours to see if fruit flies are nearby. Your local Fruit Fly Co-ordinator can help with suggestions on possible options.

  1. TECHNICAL SUMMARY – WEEK ONE AND WEEK TWO JANUARY 2018

Trapping rates of Qff adults decreased in early January 2018 (see Figure 1 and Table 1) with numbers in the GMV (350 Qff) registering fewer than those of the last two weeks of December (448 Qff) and the first two weeks of December (1,395 Qff). This does not indicate a reduction in the fruit fly population. What’s happening now is that the first generation of Qff that surged in early December is now dying out. However, as the weather is now quite optimal for Qff survival, it is likely that the first generation Qff have found mates and laid masses of eggs in any ripe or ripening fruit that is available. Qff is now present in large numbers throughout the region as a mixture of eggs and larvae in fruit, pupae in the soil, immature adults which are not attracted to traps and mature adults that are.

All urban areas registered fewer flies in early January than late December except for Tatura urban which saw an increase:

  • Cobram urban area (with 100 flies from 33 traps in early January, compared with 125 in late December),
  • Shepparton urban (with 83 flies from 24 traps [early Jan] cf 84 [late Dec]),
  • Kyabram urban (with 41 flies from 7 traps [early Jan] cf 105 [late Dec]),
  • Tatura urban (with 69 flies from 30 traps [early Jan] cf 19 [late Dec]).

Most Qff trapped during occurred in traps located within, or on the edge of, urban areas. Relatively few Qff were trapped in rural and small-town regions of the GMV. However, numbers did increase over this period in all locations, including rural areas but no rural area, except Merrigum, registered more than the proposed outbreak trigger of ≥1 fly/trap/week (Figure 2). There were individual traps (54 in all), in both rural (16 sites) and urban (38 sites) locations where the outbreak trigger was reached or exceeded (Table 2).

Again, Mooroopna, a mostly rural location should be watched closely. Mooroopna (as well as Shepparton urban) defied the general decline in captures registering 52 flies (as compared with 66 in late December).

Merrigum, also mostly rural, registered a decline with 6 flies from 11 traps – a significant decrease from the early December count of 20 flies.

Tatura rural traps declined from a total of 13 flies in 17 traps to 2 flies in that period.

For the first time, Grahamvale registered with no decrease in trap numbers – also defying the downward trend – with 5 flies found in 17 traps (5 flies were found during late December and 4 in early December).

Most Qff trapped during early January occurred in traps located within, or on the edge of, urban areas. Relatively few Qff were trapped in rural and small-town areas of the GMV. By and large, numbers decreased, or stayed the same, over this period in all locations. There were 54 trap sites that registered ≥1 fly/trap/week (Table 2). Of these, 38 sites were within urban areas (11 sites within Shepparton urban, 4 in Tatura urban, 3 in Kyabram urban and 20 in Cobram urban).

Potential Qff HOT SPOTS may exist in the URBAN areas of Tatura, Shepparton, Kyabram and Cobram and the RURAL areas of Mooroopna and Kyabram (Figure 2).

It is suggested that owners/ operators of orchards that are close to the peri-urban areas of large towns (where fruit fly numbers have increased) should prepare strategies for boundary protection against fruit flies entering their crops from the town immediately.

Growers in commercial orchards in these areas should plan to commence baiting as soon as possible.

IMPORTANT: Vigilance from now on is essential. The large upsurge seen in December, i.e. the first generation Qff is now dying out but has left very large numbers of eggs, larvae, pupae and immature adult flies in towns and gardens of the GMV. Orchard hygiene is important. If these fruit, or their parent plants, can be found and disposed of, or treated adequately then it may be possible to reduce the impact of Qff in our region.

The Code of Practice for Management of Queensland Fruit Fly (COP) suggest that area freedom from Qff should be assessed as being compromised when more than two flies are found in a trap, or adjacent traps, within a two-week period. A conservative approach is that 1 fly per trap per week (1 FTW) could be a starting point for being concerned about the safety pf a pest free area (PFA) or an area of low pest prevalence (ALPP). It is suggested that this point could be reached when trap capture rates reach 2 FTW over a two-week period. Table 2 shows that many trapping sites registered greater than or equal to 2 FTW during the first two weeks of December 2017. These sites should be checked more carefully for Qff populations, untended fruit fly host plants, or other reasons that fruit fly may create a “hot spot” situation.