Fall armyworm has been found in the South Island for the first time, with the Foundation for Arable Research confirming it has been discovered in three locations on the West Coast.
Early this week a find was confirmed in a paddock of maize near Hokitika, and since then other finds in the region suggest several maize crops are affected.
Members of a FAR and Seed and Grain Readiness and Response team, along with Dr Scott Hardwick from AgResearch/B3, visited the Hokitika property on January 12 to assess crop damage and the efficacy of control.
Nationally, the Ministry for Primary Industries has received 117 inquiries about the insect pest since September 1. The total number of confirmed positives is now at 56, up 11 from last week. Three of these finds were on the West Coast of the South Island.
The worm is thought to have been carried on storm fronts from Australia and arrived in New Zealand around February 2022.
FAR general manager of business operations Ivan Lawrie said most of the finds so far have been larvae feeding on maize crops.
Primary sector groups with government support have installed 200 traps on farms within the affected area to capture the insect in its moth stage, he said.
“We have had a few moth detections so far but mostly what we observed in the lead-up to Christmas was direct damage from caterpillars in paddocks,” Lawrie said.
This has led him to believe the insect survived the winter due to mild weather conditions, which has been backed up by modelling.
Those insects at the moth stage will also be travelling south, seeking warmer temperatures.
“The earlier sown maize crops will have a certain degree of escape because as the season progresses and the crop outgrows the presence of the pest you have less of a chance of getting severe economic damage.”
Lawrie said there was concern that the wet conditions in the upper North Island and subsequent delay in maize being sown this season meant the early development stages of the crop could be at higher risk from the insect.
One positive development is the approval of the insecticide spinetoram, commercially known as SpartaR, which can be used to control fall armyworm.
There are also promising signs that a native parasitic wasp is attacking fall armyworm. While research is still in its early stages, it could mean a degree of natural control available to farmers in the near future, Lawrie said.
The worm has been found in all of the areas found last season including Northland, Waikato, Bay of Plenty and Taranaki. Lawrie said they are processing reports from other regions where it is suspected the insect has spread.
“Going forward now, the main thing is to continue reporting. We will continue to collect the data from the moths from the traps but we need growers to be walking their fields and finding any signs of damage and reporting any finds to the MPI.”
This helps FAR build a better picture for modelling and understanding the insect.
“There is no downside for a grower to report any finding, only an upside. There’s no chance of the crop being destroyed or notices being put on paddocks. There should be no fear in reporting a new find.”
