In what is described as a serious threat to crops, the minister of agriculture, land reform and rural development, Thoko Didiza, urges farmers to take precautionary measures in controlling the Fall Armyworm.
QU Dongyu, the director-general of the Food and Agriculture Organisation of the UN, says Spodoptera frugiperda is one of the top ten devastating plant pests affecting food and agriculture. It has been ravaging farmlands in more than 70 African countries since 2016 after originating in the Americas.
The pest, notes Qu, threatens up to 80 million tonnes of maize alone worth $18 billion per year in Africa, Asia and the Near East. It feeds on large numbers on the leaves, stems and reproductive parts of more than 350 plant species.
In South Africa, the Fall Armyworm is a regulated pest in terms of the agricultural pests act, says Didiza.
“It is a disastrous exotic pest with a wide host range and, if not properly controlled, it may lead to damage of the host crop and/or yield losses. It is present in all provinces. However, the level of infestation vary per province, district or area.”
With early rains experienced in different parts of Mzansi, high infestation levels of Fall Armyworm should be expected, warns Didiza. This differs from the previous season where there was limited to no rain, accompanied by reduced outbreaks of the hairless, striped caterpillars.
Take precautionary measures now
Didiza therefore makes “a clarion call to (the growers of) all maize and related host crops, such as sorghum and sweet corn, to take precautionary measures in controlling it.”
All citizens have a significant role to play too, she says. “Farmers and community members are encouraged to do regular scouting of Fall Armyworm, particularly in younger plantings. They can call the nearest local agriculture centre for technical advisory.”
Despite its name, the Fall Armyworm is actually not a warm, says prof. Kenneth Wilson from the Lancaster Environment Centre at Lancaster University in the UK. He explains to The Conversation that armyworms are actually the caterpillar stage of moths.
“They are called armyworms because when they have ravaged a crop they march along the ground like a vast army of worms in search of more food.”
Didiza advises farmers and community to “diligently and vigilantly” scout for egg packs, leaf damage and caterpillars as well as trapping, to ensure early detection for effective control of Spodoptera frugiperda.
“The moth can be caught in traps with a lure, which can also serve as an early warning of the presence of the pest,” she says. For agrochemical control, farmers are advised to consult government’s official list of registered agrochemicals.
5 practical tips for farmers
It is best to start agrochemical spraying while the caterpillars are smaller than one centimetre. Big caterpillars (anything bigger than a centimetre) crawls deep into the leaf whorls of maize plants, for example. That makes it difficult to reach them when agricultural chemicals are applied.
Note that this pest can rapidly develop resistance to agrochemicals. It is therefore highly recommended to rotate the agricultural chemicals within the cropping season. Do this in accordance with the IRAC’s resistance group and mode of action.
Seeds treated with an insecticide may not provide effective control for the duration of the first window. If additional foliar applications are required in the first window, they should be of a different mode of action, and should be applied no later than 25 days after planting.
According to Didiza the European Union has extended emergency import measures for hosts of Fall Armyworm, including sweet corn, peppers and eggfruit. Growers must ensure they comply with these measures before they apply for a phytosanitary certification with the department of agriculture, land reform and rural development.
Fall Armyworm has an generation period of approximately 30 days. In other words, there are approximately 30 days to ensure that sequential generations of the moth are not exposed to the same insecticide mode of action in sequential insecticide applications.