Fall armyworm update 14 April 2023

The fall armyworm life-cycle is slowing down as the weather gets colder, however it is important to stay vigilant and continue scouting maize and neighbouring crops. 

Key points:

• The fall armyworm life-cycle is slowing down as the weather gets colder.
• With a reduction in the surveillance of standing maize, it is important to stay vigilant and scout harvested crops and any neighbouring paddocks as fall armyworm will turn to a large variety of crops as a food source. They have been observed on ryegrass and clover in a harvested maize paddock. Volunteer maize should not be overlooked either.
• Any information on new host plants is welcome as we begin to understand overwintering capabilities.
• As it has become apparent that fall armyworm is unlikely to be eradicated in New Zealand, the fall armyworm response will end, and we will go into Long Term Management on Friday 21 April. This will be an industry-led management transition. 
• To date there are a total of 139 confirmed reports of fall armyworm across New Zealand. There have been no new finds this week although there are some moths from existing confirmed properties being identified.
• Fall armyworm has been confirmed in North Canterbury sweetcorn, although in small numbers. A report on a sweetcorn crop from last year in a similar area has also been confirmed and added to the total number of confirmed reports.
• The last few weeks have seen large moth flights in Northland, highlighting the name ‘FALL’ armyworm, where populations build up to potentially cause devastating damage to autumn crops.
• At this stage we are still in a response. All finds must be reported to MPI here or by calling 0800 80 99 66
• The insecticide Sparta® is now on label for both aerial and ground applications for the control of fall armyworm on maize and sweetcorn crops. Consult with your advisor.
• Avoid the use of insecticides that are ineffective on fall armyworm and potentially harmful to beneficial insects such as parasitic wasp Cotesia sp. which will help contain the numbers.
• There are no negative consequences to growers for reporting, as this pest will not be controlled by removing crops.

For the latest identification guides click here and MPI Website here, or contact Ivan Lawrie ivan.lawrie@far.org.nz or Ash Mills ashley.mills@far.org.nz

For other useful tools and guides on detection and identification, consult the FAR website.