Native budworm are active
Four weeks ago, DPIRD technical officer Dave Nicholson (DPIRD) installed a number of native budworm traps in the northern agricultural region. Over a three week period native budworm moth were captured by traps at: Northampton (53 moths), Mingenew (15), Coorow (8), Tenindewa (3), Eurardy (3) and Yuna (1). Dave also did some sweep netting of the crops in the trapping area and at this stage no caterpillars have been detected. This indicates that these moth flights are probably fairly recent.
This week low numbers of native budworm moths were captured in traps at Mingenew N.E (2 moths), Dalwallinu (1) and Cunderdin (1).
Although the trap numbers are relatively low at this stage the unpredictable nature of the native budworm means larger flights could arrive in the coming weeks.
Dan Taylor (DKT Rural Agencies) reports finding native budworm caterpillars in an early flowering canola crop near Tammin. At the moment, the damage is at a low level with just a few holes being chewed in the leaves.
Given what has happened in recent years with high numbers of native budworm moths arriving earlier than usual in some WA locations and causing significant damage to young crops it would be advisable to monitor crops over the coming weeks for budworm caterpillars, particularly in those areas in the northern and eastern grainbelt closer to the pastoral areas.
Identifying and managing native budworm moths
Native budworm caterpillars vary greatly in colour from green through orange to dark brown. They usually have dark stripes along the body and are sparsely covered with fine bristles.
The adult form of the native budworm is a moth that has rapid, low-level flight that takes a zig-zag path and ends with a dive into a crop or shrubs.
During average spring temperatures it takes about seven days for any native budworm eggs laid on crops to hatch into caterpillars. It then takes a further two weeks for the caterpillars to grow in size to about 5mm when they can then be detected in sweep nets. With cooler temperatures in many areas the caterpillar’s life cycle is likely to take longer than three weeks to reach the size of 5mm.
Native budworm moth flights are often variable and unpredictable but moths generally prefer to land in flowering crops in preference to nearby crops that are yet to flower. Native budworm caterpillars most frequently attack the fruiting parts of plants, but at this time of year the caterpillars will feed on the terminal growth and the developing flowers and leaves.
It is important to correctly identify moths and caterpillars to make the best management decision. Capture a moth or caterpillar then take a clear and close-up photo of the insect. Taking close-up photos of any distinguishing features that it may have, such as hairs or spots on its back, will help our entomologists make a diagnosis. You can then send an identification request via the free PestFax Reporter app or by emailing the PestFax team.
Pesticide options for the control of native budworm can be found in DPIRD’s 2021 Winter Spring Insecticide Guide.
Detailed information on native budworm can be found at DPIRD’s Management and economic thresholds for native budworm.
For more information contact Alan Lord, Technical Officer, South Perth +61 (0)8 9368 3758 or +61 (0)409 689 468.
Article authors: Alan Lord (DPIRD South Perth) and Cindy Webster (DPIRD Narrogin).