Abstract
Mixed swards of alfalfa (Medicago sativa L., CV. Thor) and orchardgrass (Dactylis glomerata L., CV. Kitamidori) were established every year from 1978 to 1987, and dry matter yield of the swards were surveyed for six years, respectively. Since 1986, Verticillium wilt (V. albo-atrum REINKE et BERTHOLD) occurred, and the yield of alfalfa decreased rapidly. Alfalfa disappeared entirely in the swards established in 1982 and 1983 (Fig. 3). Effects of the disease were severer and much more destructive compared with wet-injury in August, 1981 (Fig. 1). The disease reduced total yields of the swards in three cases, that is, the 3rd year's stand established in 1986, and the 4th and 5th year's stand established in 1984 (Table 1).
