Read the latest Fall armyworm update as of 2 February 2024.
Key points
- The 2023/24 growing season has 69 confirmed reports. These have come from Northland, Westland, Tasman and now Bay of Plenty.
- There are also two unconfirmed reports in Waikato and one suspect moth caught in the Manawatū-Whanganui region.
- In Northland the anticipated second generation moth flight has been recorded and newly hatched ‘neonates’ have been observed. These neonates are the third generation for the 2023/24 season and pose a potentially greater economic threat. Keep crop scouting and liaise with your advisor to seek advice.
- FAW is widespread across the West Coast. Larvae have progressed to the late instar and pupa stages. Canterbury sweetcorn growers should keep an eye on crops as there is the potential for moths to be blown east, as was observed last season.
- However, in general, reported FAW populations appear to be small and localised, and well below economic thresholds.
- Sweetcorn growers need to remain vigilant at all crop stages as there have been reports of cob damage due to FAW damage. FAW tend to sit behind the developing cob and eat into the side; this is unlike corn earworm that occupy the tassels, eat the top of the cob and may not be noticed until after harvest.
- The earlier FAW is identified the likelier effective management will be achieved.
- Parasitism of FAW, by the parasitic wasp Cotesia sp, is being observed across the country. Small FAW infestations appear to be kept in check by the wasp.
- Corn earworm populations have been observed more frequently across the country. Corn earworm eggs are laid in the tassels and larvae make their homes at the top of the forming cob.
- Your observations are important. Please record them and inform us; without them it is hard to validate the modelling work we are doing.
- The insecticide Sparta® is on label for aerial and ground applications for controlling fall armyworm on maize and sweetcorn crops. Consult your advisor and avoid using insecticides that are ineffective on fall armyworm and potentially harmful to beneficial insects such as parasitic wasp Cotesia sp.
Photo (above top): Cotesia spp cocoons in sweetcorn. The cocoons appear like multiple cotton wool buds around 2mm long. These are the result of a larvae being parasitised and the wasp larvae progressing to the adult stage of their lifecycle.
Photo (above middle): Cotesia spp adults hatched in captivity from an unknowingly infected FAW larva from maize in the Westland Region. Up to 30 wasps have emerged from this particular cocoon mass.
Photo (above bottom): Severe weather events with high rainfall have caused some larvae mortality and the saturated ground has drowned pupa. The cannibalistic behaviour of later instar larvae and natural predation from a wide range of predatory insects will further reduce some FAW populations.
https://assets.far.org.nz/Cotesia-ruficrus-factsheet.pdf
At this date last year there were 100 fall armyworm finds nationwide, including Northland, Auckland, Waikato and Taranaki
- To date, confirmed finds this season are in Northland, Westland, Tasman and BOP.
- Average temperatures were considerably lower in regions compared to winter and spring last year.
- Marginal areas may have seen FAW populations unable to overwinter and depend on migration from more favourable areas.
- If you are scouting your crops inform us even if you do not find FAW, THIS POPULATION DATA IS USEFUL. The data provided has been fantastic, it will enable the development of the modelling and has been extremely helpful for ongoing research aiming to develop predictive tools.
What to do if you think you find fall armyworm
- Photograph it: It can be easily mistaken for other species, so if you suspect Fall armyworm, take a good quality photo, and be sure to include the head, body and rear of the larvae. This can be in multiple photos if necessary. 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 will be welcomed and are important for positive identification and testing.
- Contact us: Contact the Foundation for Arable Research at FAR@far.or.nz or Biosecurity Officer Ash Mills at ashley.mills@far.org.nz
- All data recorded (even zero finds) are valuable for the validation of modelling platforms and for understanding the pest in New Zealand.
- If you are keen 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 welcome
Consult the FAR website for the latest resources and identification guides
FAR Research | Welcome to the Foundation for Arable Research
Listed below are useful updates, tools and guides on detection and identification
FAR Research | Fall armyworm identification and background
For advice around Sparta, FAW information and requesting a great FAW glovebox guide - Fall Armyworm (corteva.co.nz) and this FAW Sparta technote Salesforce
A farm Biosecurity Register is a great way of reducing the risk of unwanted weeds, pests and diseases arriving on your doorstep. Do you have one? Find out more here FAR Research | Arable Biosecurity Risk Register
Thresholds for economic damage
SGRR Davis Scale Guide - 86d44eb4-7d19-5ce5-befe-4dd32eeca38c.pdf (far.org.nz)
Plant health Australia provides useful guidance for this: (see photo below)
Useful insight from over the ditch - https://www.planthealthaustralia.com.au/fall-armyworm/
