Annual Kentucky Alfalfa Variety Test Report, Progress Report 351. Clavibacter michiganense subsp. Stunted, yellowish-green plants are evident during regrowth following cutting. Usually does not appear until second or third year of stand. Only scattered plants show symptoms at any one time.
Bacteria survive in dead taproots and stems.
Infects through the cut ends of newly mowed stems, feeding wounds of the clover root curculio, and other wounds to crowns and roots. Also spreads on cutter bar. Grow only varieties with at least moderate resistance to bacterial wilt. Use varieties with higher resistance levels in fields where the disease has been diagnosed. Cut alfalfa only when foliage is dry.