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Those swellings on the roots could be root-knot nematodes

Have you ever removed a plant in your garden and noticed some swellings on the roots? You could be having a visit from root-knot nematodes (RKN).

As the female RKN develops and the body expands, the root tissues also increase to accommodate the female RKN resulting in the swellings or ‘knots’ used for diagnosing RKN.

Root galls on cucumber caused by the Javanese root-knot nematode Meloidogyne javanica

Root galls on cucumber caused by the Javanese root-knot nematode Meloidogyne javanica at the UF GCREC. Photo credit: J. Desaeger.

Because of the warm subtropical/tropical conditions and sandy soil, all kinds of plant-parasitic nematodes (PPN) are able to thrive in Florida, including most species of RKN. RKN impact more crops than any other PPN. Also, since a lot of vegetables, ornamentals, and small fruits are grown in Florida, the RKN has a wide variety of food sources available to them.

The RKN are very smart pests. They can hang around other plants such as weeds if the preferred crop is not in the field, and only come out to cause damage when the crop is planted. This means that this group of nematodes is continuously a problem in Florida’s agriculture, and are often challenging to control once inside the root.

Some common RKN in Florida include Meloidogyne arenaria, M. incognita, M. javanica, M. graminis, M. floridensis, M. enterolobii, M. partityla, and M. haplanaria.

If you need an expert to help check if you have an RKN problem in your field or garden, you can send your root or soil sample to the University of Florida Nematode Assay Lab. The Nematode Assay Lab website provides detailed instructions on how to collect the root/soil samples for nematode diagnosis.

Check out the following UF EDIS publications for additional information about RKN.