A North Canterbury sweetcorn crop is among the latest discoveries of fall armyworm, raising the total to about 140 sites this year, as the strategy swings to long-term management of the pest.
The discovery of armyworm in small numbers in North Canterbury failed to surprise experts as computer modelling suggested weather patterns would inevitably bring it down from the North Island.
The maize pest was virtually circling the region after being traced in the neighbouring West Coast region, initially on a Hokitika farm, and in Takaka. Further south remains clear after an initial false alarm in a Central Otago paddock.
Despite plotting its descent, arable officials were surprised to learn the pest had settled in small maize pockets of frost-free areas on the West Coast.
For the most part armyworm hasn’t become as destructive as in warmer parts of the globe and there are only a handful of paddocks damaged in the upper North Island, which are being controlled so far by insecticides.
Pest management officials made the call to change the fall armyworm response to a long-term management strategy last Friday .
The Foundation for Arable Research says the change of tactics is an industry-led management transition.
The foundation revealed a report on a sweetcorn crop from last year in a similar area to the North Canterbury discovery had been confirmed and added to the total confirmed reports.
Over the past few weeks large moth flights are being seen in Northland, typically when populations build up to potentially cause devastating damage to autumn crops.
Fall armyworm has been observed on ryegrass and clover in a harvested maize paddock.
The foundation says it is important that growers stay vigilant and scout any neighbouring paddocks in the absence of maize and sweetcorn as fall armyworm may turn to other crops for a food source.
Mulching or grazing any regrowth is being recommended as a good option to reduce their numbers.
Growers are relying on the insecticide Sparta for aerial and ground control on both maize and sweetcorn crops, while beneficial insects such as a parasitic wasp are helping to contain numbers.
