The first FAW find for the 2023/24 growing season has been confirmed in Northland. Three other moth captures at different locations require further analysis before confirmation.
The first FAW find for the 2023/24 growing season has been confirmed in Northland. Three other moth captures require further analysis before confirmation (or not).
Surveillance is also identifying localised Cosmopolitan armyworm, greasy cutworm populations and possibly, very early instar tropical armyworm. Observations of parasitised cosmopolitan armyworm are encouraging, as the same parasitoid wasp, Cotesia sp., also attacks FAW.
Earlier planted crops are less likely to suffer significant economic loss as early-season FAW populations are yet to build up sufficient numbers to cause such damage. However, keep looking, as the earlier FAW are identified the easier they are to manage.
Keep an eye out for newly hatched FAW larvae (around 1.5mm in length) or windowing on leaves. As the larvae grow, they , disperse to surrounding plants, taking shelter within the maize whorl as the plants develop. As always, please record any observations and let us know.
Control
The insecticide Sparta® is on label for aerial and ground applications for controlling fall armyworm in maize and sweetcorn. Talk to your advisor and avoid the use of insecticides won’t kill FAW and may harm beneficial insects such as parasitic wasp Cotesia sp. The Davis Scale of Economic Damage outlines damage thresholds, providing guidance on the likely benefits of insecticide use.
What to do if you think you find fall armyworm
Photograph it: FAW is easily mistaken for other species, so take a good quality photo/s (including the head, body and rear of the larvae). This great guide from the Queensland Department of Agriculture and Fisheries will help How to take a photo of FAW_24Mar20 (thebeatsheet.com.au)
Catch it: Samples are important for positive identification and testing.
Contact FAR: FAR@far.or.nz or Biosecurity Officer Ash Mills at ashley.mills@far.org.nz
- Trap network and active scouting and reporting have been fantastic throughout the winter and spring and are much appreciated.
- All data recorded (even zero finds) are valuable for the validation of modelling platforms and to understand the pest in New Zealand.
- If you would like to monitor a trap and share scouting information please get in touch.
- Data and observations of parasitism as well as potential relationships with other pest species would also be welcomed.
Mythimna (Cosmopolitan armyworm) found in a Northland maize crop. Note characteristic cutting damage around the edge of leaves with the larvae found in the centre of the plant. The parasitic wasp known to parasitise FAW, were originally released to control Cosmopolitan armyworm and other caterpillar pests in early 1970s.
Photo courtesy Dr Jenny Dymock who has identified Cotesia sp cocoons on a parasitised Cosmopolitan armyworm larvae.