As many of you would’ve heard or read by now, Biosecurity New Zealand and primary sector partners are continuing to respond to the discovery of fall armyworm in New Zealand. It is important that you have the below information no matter what sector you’re in because, despite the fact that fall armyworm larvae favours sweetcorn and maize, they feed on more than 350 plant species, so livestock farms need to keep a lookout as well.

Thus far, there has been confirmed detections in Tauranga (eggs only) and in paddocks near Hamilton, in South Auckland, Waitara and Gisborne. MPI has extended the request for paddock checks to growers in the top-of-the South Island, but they say the risk for South Island crops is lower.

Fall armyworm thrives in very warm climates and although it’s unlikely to survive winter in most areas of New Zealand it’s important we remain vigilant in detecting this pest. If it were to survive overwinter here, the destruction this pest can cause if they ‘army’ could be severely detrimental to New Zealand’s primary sector. Information about this pest and what to look for can be found on Biosecurity New Zealand’s web page here

What to do if you find fall armyworm

It’s extremely important that even if you’re unsure whether you have detected fall armyworm on your property or not, that you follow the steps below as soon as possible. For help, you can find an identification sheet here.

1. Photograph it: It can easily be mistaken for other species, so if you suspect fall armyworm, take a photo (caterpillars at least 2cm long).
2. Report it: Call Biosecurity New Zealand’s Pest and Disease Hotline (0800 80 99 66) or report online. Alternatively, you can report via the app here.
3. Manage it: Management options for crop regrowth/volunteers, include:

• Spray plants with any herbicide you have in the shed, follow by tilling to a minimum 10cm depth.
• Spot spray the volunteers with insecticide (ideally diamides or spinosyns/spinosoids), or;
• Hand pull the volunteer plants and securely dispose them if there are small numbers;
• Mow or intensively graze the field to remove the plant hosts/feed source and consider planting a different crop next season

If you have a whole field planted with maize or sweetcorn:

• Harvest for silage/balage and ensure the bulk host material is removed from the site and take steps to manage any volunteer crop coming through as per the above.

More information:

Radio New Zealand article with Foundation for Arable Research (FAR) operations manager Ivan Lawrie here.

Radio New Zealand interview with Alison Watson, who heads the secretariat of ASEAN’s Fall Armyworm Action Plan in south-east Asia here.