HPIPM:Alfalfa Stem Nematode

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Author: Ned Tisserat and Gary Franc

Taxonomy

Domain	Eukarya
Kingdom	Animalia

Scientific Name

Nematoda

Scientific Name Synonyms

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

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.