Cause: Alfalfa stem nematode (Ditylenchus dispaci); Chrysanthemum foliar nematodes may also be found in diseased stem and bud tissue.
Occurrence: Plants exhibit symptoms throughout the year, but may be most intense in spring before first cutting.
Key Symptoms:
· Twisted, crinkled, yellowed or white leaves ‘white flagging’
· Severe stunting with compacted crowns
· Stem buds swollen at base and distorted
· Winter kill commonly associated with infestations
· Symptoms more intense in fields with heavy soils
· Laboratory analysis necessary to confirm presence of nematode
Pathogen: The nematode survives in soil or buds. It feeds on the developing buds.
Management approaches:
· Plant resistant varieties. See the following sources for variety ratings:
o University of Wisconsin forage pages http://www.uwex.edu/ces/forage/pubs/varinfo.htm
o University of Wyoming Alfalfa Disease Management Publication B1136 http://ces.uwyo.edu/PUBS/B-1136.pdf
· Use of clean seed and restricted movement of equipment from fields with known infestation
Categories: Alfalfa, Diseases, Alfalfa stem nematode
Date: 03/01/07