It is unnecessary to spray as preventative measure against fall armyworm, says Dr Johnnie van der Berg, entomologist from the North-West University.
He warned members of the KwaZulu-Natal No-till Club at the annual conservation farming conference to constantly be on the lookout for the plague. However, they should not be fooled into using gimmicks and applying unnecessary control measures.
“You have to constantly watch your plants, identify the plague early and then spray. Then there is almost a guarantee that the chemicals will work.”
He said reports from the previous season that chemicals are ineffective against the new invasive pest, are largely based on the fact that spraying took place when the worm was already too big. Certified chemicals are only effective on worms in the infant stage.
The pest, which landed in southern Africa for the first time in 2016, usually targets maize and then stays put, Van der Berg said. It prefers maize and sorghum, and maybe wheat, but not up to 100 crops, as reported.
The fall armyworm is a tropical species that originated from South America and won’t be able to enter a dormant phase and survive when temperatures drop below 7-10 degrees Celsius.
He said there are only a few small areas in South Africa where the worm could survive during winter. This includes the northern parts of Limpopo, parts of the Lowveld and maybe the northern parts of KwaZulu-Natal, where it will have to be managed in the future.
South African scientists have launched a large, three-year research project focusing on the fall armyworm, financed by the Maize Trust. The trust gives financial support to the local maize industry for research and other programmes.