The 2023/24 growing season has 85 confirmed reports of fall armyworm. These have come from Northland, Westland, Tasman, Bay of Plenty, Auckland and Waikato.
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.