Root Knot Nematode Control: Tips For Managing Nematodes In Cactus

(Image credit: fotocelia)

Nematodes are tiny, microscopic roundworms that live in the soil and feed on plants. While some are nitrogen-fixing and actually beneficial, others can cause serious damage and open up pathways in plants for harmful bacteria and disease. Root knot nematodes are very common among most cactus species. Keep reading to learn more about how to detect cactus root nematodes and the best methods for managing nematodes in cactus roots.

Cactus Root Knot Nematodes

Nematodes feed on plant roots by digging into the root’s cell walls with a sharp, pointed feeding tool called a stylet. The puncture wound created by the stylet is usually more of a problem than the presence of the nematode itself because it creates an opening that allows bacteria and fungi to enter easily into the plant, infecting it from within. Root knot nematodes are a specific kind of nematode that feeds on roots and usually create telltale fleshy masses, or “galls” on the roots. These galls make it difficult for the cactus to draw up water and nutrients properly. Since the galls form underground, it’s necessary to look for aboveground signs that your cactus is infected. The lack of adequate water and nutrients can make for a plant that’s yellowed, shriveled, and stunted looking.

Treating Nematodes of Cactus

The best method for root knot nematode control is prevention. If you’re planting your cacti in containers, always use a new, sterile potting medium and clean any used containers thoroughly. If cactus root knot nematodes are already in your soil, it’s possible to treat them with nematicides. These chemicals usually come in either granular or liquid form and can be applied in a few different ways. Always follow the application instructions on the label exactly. It’s easier on the plant to treat the soil before planting, but you can treat the soil around your established cactus this way as well.

Liz Baessler
Senior Editor

The only child of a horticulturist and an English teacher, Liz Baessler was destined to become a gardening editor. She has been with Gardening Know how since 2015, and a Senior Editor since 2020. She holds a BA in English from Brandeis University and an MA in English from the University of Geneva, Switzerland. After years of gardening in containers and community garden plots, she finally has a backyard of her own, which she is systematically filling with vegetables and flowers.