Read here for the full Fall armyworm update up to 9 February 2024
Key points
- The 2023/24 growing season has 85 confirmed reports. These have come from Northland, Westland, Tasman, Bay of Plenty, Auckland and Waikato Regions.
- Suspect moths from Manawatū-Whanganui will be identified via DNA testing.
- A large moth flight was observed in Northland last week. Expect larger FAW populations in the region. Keep crop scouting, especially later and replanted crops, and seek advice as required.
- FAW is widespread across the West Coast. They are in the pupal stage and beginning to emerge in northern districts. Canterbury sweetcorn growers should keep an eye on crops as moths could be blown east, over the Alps, as was observed last season.
- Expect moths to arrive in multiple regions as populations increase and progress through generations.
- 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 silks, 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 silks 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: FAW Modelling courtesy of Dr Nick Davies (AgResearch). The latest model run is reasonably close to observations on the ground given the early stage of data capture. The model is possibly slightly behind real time, the more reports received (even 0 finds) from all regions from scouting or checking traps will continually validate the development of this tool.
Photo above middle: Fall Armyworm in Waikato, photo courtesy of Catherine James (Fruitfed). These are some of the first larvae reported in the Waikato region.
Photo above bottom: Suspect FAW Moth, photo courtesy of Catherine James (Fruitfed) Moths captured in Waikato traps could correspond with known moth flights in Northland. These moths will undergo identification from AgResearch staff as they have lost scales as a result of capture and potential egg-laying. Collecting samples enables accurate identification and helps to understand population distributions.
At this date last year there were 107 fall armyworm finds nationwide, including Northland, Auckland, Waikato and Taranaki
- To date, confirmed finds this season are in Northland, Westland, Tasman, BOP, Auckland and Waikato.
- 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.
Photo: NZ dragonfly, Uropetala chiltoni. One of several dragonflies observed in a Westland paddock, one of which was observed carrying larvae of unknown species.
One of the most encouraging observations this season has been the wide distribution of the parasitic wasps, but there are a multitude of insects that will predate FAW. Look after them.
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
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 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 welcomed.
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
Thresholds for economic damage
Plant Health Australia provides useful guidance for this:
Useful insight from over the ditch - https://www.planthealthaustralia.com.au/fall-armyworm/
SGRR Davis Scale Guide - 86d44eb4-7d19-5ce5-befe-4dd32eeca38c.pdf (far.org.nz)