Oklahoma State University Stillwater, OK
Oklahoma Alfalfa Oklahoma Cooperative Extension Service Oklahoma Agricultural Experiment Station

Stem Nematodes in Alfalfa
Every once in awhile we have a horrible year for stem nematodes, a small worm that we usually don't worry about.  In many fields the first symptom was that the alfalfa was not greening up but there weren't any bugs. Stem nematode symptoms have been seen in several counties, and they have been positively identified in several fields. There are areas in many fields that still have not greened up and many of the plants are dead.  While no chemical controls are effective, and cleaning haying equipment is sometimes recommended between fields, the only realistic way to minimize the effects of stem nematodes is leaving an infected field out of alfalfa for several years (5 or more). Note areas where stem nematodes symptoms show up this year. Hopefully some of the plants will come out but many will die. Infested areas of the field will be bigger next year.  Varieties that are reported to be resistant do not seem to fair much better in Oklahoma than those that are known to be susceptible.  Stem Nematode Damage
John Caddel, Forage Agronomist  Department of Plant and Soil Sciences  Oklahoma State University

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