The time to monitor for the native budworm, the cotton bollworm and loopers is when fruit trees start flowering.
The native budworm, the cotton bollworm and the larvae of geometrid moths (loopers) are serious pests of apple production in all Australian fruit growing regions.
Management of these pests involves a combination of weed management, biological control, entomopathogens, early season monitoring and careful selection of pesticides to avoid disrupting predators and parasitoids.
Helicoverpa
The native budworm Helicoverpa punctigera and the cotton bollworm Helicoverpa armigera (also known in Australia as tobacco budworm, tomato grub or corn earworm) can attack pome fruit from pink bud through to early fruit development.
H. armigera has developed resistance to a wide range of pesticides and is generally more difficult to control.
In southern Qld it overwinters as diapausing pupae in the soil under late summer crops and emerges in spring during October but does not become the dominant species until mid-summer and autumn.
H. punctigera breeds on flowering plants in inland Australia, and in southern parts of Australia it overwinters as pupae from which moths emerge in spring. In Victoria it emerges before H. armigera.
Both species are capable of long-distance migration on high-altitude winds that precede cold fronts.
Migrating H. punctigera arrive in southern fruit growing states in August and start laying eggs.
Pheromone traps can be used to monitor the activity of both species, but because they have different pheromones this requires the use of separate traps.
In pome fruit growing regions, the moths can invade orchards from pastures and other crops. Often this means that the moths have mated before arriving in the orchard around the time fruit trees are starting to flower.
Pheromone traps only capture male moths, not females, and capture of males indicates females are likely to be present and laying eggs. Because the eggs are laid during the time that bees will be active it is important to make careful choices of control measures.
Budworm larvae bore into developing flower buds, flowers, developing fruitlets and unfolding leaves, and can cause considerable damage and fruit drop.
Damaged fruit that remains on the tree may become deformed by a deep depression with scar tissue. These scars are larger than those caused by the apple dimpling bug and the deformities are distortions rather than dimples.
Some chemical control choices will affect bees and therefore pollination; biocontrol agents that prey on the eggs of Helicoverpa and other pest species may be affected; and the costs of counteracting the side effects may outweigh the benefits of controlling the budworms.
Loopers (cont next issue)
See this article in Tree Fruit November 2022
Reproduced with permission and thanks to APAL and Australian Fruit Grower
Acknowledgements: The PIPS3 Program’s Strengthening cultural and biological management of pests and diseases project (AP19002) has been funded by Hort Innovation, using the apple and pear research and development levy, contributions from the Australian Government and co-investment from Agriculture Victoria. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.
