Cutworms are a persistent pest for South African farmers, particularly those cultivating potatoes. These pests, known for their destructive feeding habits, can cause significant crop losses if not managed properly.
Entomologist and PhD candidate at the Univerity of Pretoria, Blessing Mphahlele provides insight into their life cycle, prevalence, early infestation signs, and the best management strategies for farmers.
“The name cutworm says that it cuts whatever that comes across and then in most cases, it cuts the seedlings just near the soil surface,” says Mphahlele. This destructive behaviour makes cutworms particularly dangerous for crops like potatoes, where they attack seedlings and young plants, leading to poor establishment and reduced yields.
Cutworms are widespread across South Africa. While adaptable to many conditions, cutworms are particularly active during the winter due to their relationship with weeds.
“They’ll normally lay most of their eggs on the weeds, which will actually become abundant during the spring period when most farmers are starting with their crop production activities.”
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The cutworm has four distinct life cycle stages: egg, larva, pupa, and adult moth. “The female moth can lay over a thousand eggs on the soil surface and on plant materials, especially in fallow fields,” Mphahlele says. The larval stage is the most destructive, as larvae feed on young plants, causing severe damage.
Early signs of cutworm infestation
Mphahlele highlights that early detection is key to managing cutworm infestations. “The early indications are that you notice wilting and the losses of your seedlings,” he explains. Larger larvae begin cutting seedlings at the base, while smaller larvae create holes in leaves.
The nocturnal nature of cutworms makes them difficult to detect during the day. “During the day, because it’s nocturnal, it is very rare for farmers to find it crawling between its plants.”
Examining weeds and digging around the base of plants can help locate hidden larvae.
In this episode, Mphahlele also discusses:
- Effective cutworm management strategies
- Integrated pest management (IPM) approaches
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