Orchardists often complain about “backyard trees” in urban areas particularly in major horticultural areas and there is some justification for this as it has been established that for Queensland Fruit Fly early detections are almost always in these areas. Queensland Fruit or Qfly overwinter as an adult and in the colder southern areas of NSW and Victoria they need to find a warm place to survive and urban household environments offer the ideal place. As the temperature rises in early spring the fruit fly is able to forage for food and moisture and early fruit becomes a target for egg laying, the diversity of available host plants in urban areas greatly assists in early outbreaks.
As numbers build up the fruit fly will then range wider into commercial orchards particularly around the boundaries adjacent to the townships. A similar scenario exists with the Mediterranean Fruit Fly or Medfly found at his stage only in WA and unlike its eastern states cousin this fly can overwinter as a pupae as well. However early urban outbreaks are the most common source of commercial orchard infestation as the majority of commercial growers control this pest it is unlikely they will contribute to the overwintering.
However, the poor home grower that enjoys home grown product is really at the mercy of the Fruit Fly as there are a very limited number of products available that will provide any control. Exclusion netting is really the only answer on a individual basis and area wide trapping or baiting involving all residents is also effective. Host plant removal has been promoted to assist area wide programs and this has proven effective. The future looks fairly grim for the home gardener particularly in areas where there are no commercial orchards as there will be little to no support from a community basis to manage this pest. Residents in the Sunraysia region are being supplied traps to reduce the pest pressure on the orchards but unfortunately outbreaks still occur as our current range of attractants and lures compete with the naturally occurring sources and the effectiveness varies from season to season. There is a considerable amount of research being done on improving area wide management which ultimately assist a future SIT program but regrettably we are still some distance from effectively managing this pest.
Respective state governments are promoting various schemes to manage this very destructive pest but unfortunately the limitations are the limited products available and the need to effectively cover an entire area. The other issue in the urban landscape is the range of susceptible host plants including feral trees and garden plants. Both the Queensland Fruit Fly and the Mediterranean Fruit fly do attack ornamental trees and shrubs such as Crab Apples, Roses Hips, Olives to name a few.
This pest is simply not going to go away, we need to manage it and we can do so in commercial orchards reasonably effectively using the tools we have available but we need to support the home gardeners if we are going to achieve effective area wide management.