You Are Here: Management Updates 1999 Archive June 25, 1999

Date: June 25, 1999
Category: Nematodes
Subject: Root Knot Nematodes in Turf

Meloidogyne hapla (Northern root-knot nematode) and M. graminis (false root-knot nematode) are two species that we occasionally find in fine turf. While not nearly as common as lance and stunt nematodes, the occurrence of root-knot should be of concern. As the common name implies, root-knot nematode infection results in small galls or swelling of the roots. The Northern root-knot nematode, produces galls from 1/16 to 1/8 inch in diameter. Symptoms from the false root-knot nematode are much harder to see because only swelling of the roots occurs. Our research has shown that root-knot nematode populations appear to be highest in the Spring and in the Fall. This is somewhat deceptive because when root-knot populations appear to be low (from June through August) it is because they are residing in the roots, developing into egg-laying females. It is impossible at this time of the year to determine if root-knot is at potentially damaging levels. Also, when the nematodes are within the roots, Nemacur has little, if any effect. We have identified putting greens where root-knot nematodes have developed very large populations, and are contributing to decline of the turf. Populations in the spring were ten fold higher than they were 5 weeks later. The nematodes didn't go away, they moved into the roots where the damage is being done. If you have had any indication of root-knot nematodes from assays conducted in the last few years, it would be a good idea to have additional assays carried out. Populations appear to be highest in early May, and September through October.

- Submitted by: Dr. Rob Wick