HPIPM:Alfalfa Stem Nematode

Author: Ned Tisserat and Gary Franc

Taxonomy

Domain	Eukarya
Kingdom	Animalia

Scientific Name

Nematoda

Scientific Name Synonyms

Nemata

Nematodae

Common Name

nematodes, roundworms, threadworms

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:
• University of Wisconsin forage pages http://www.uwex.edu/ces/forage/pubs/varinfo.htm
• 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

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.