Identification of Verticillium dahliae and V. albo-atrum Causing Wilt of Tomato in Korea

In 1997, 103 isolates of Verticillium were obtained from roots and stems of tomato plants showing wilt symptoms in greenhouses in eight areas of Korea. Out of these isolates, 75 were edintified as V. dahliae while 28 were identified as V. albo-atrum based on their morpho-logical and cultural characteristics. Both Verticillium species produced colonies with conidiophores, which were more or less erect, hyaline, with verticillate branches, and with 3-4 phialides at each node. V. dahliae produced microsclerotia, while V. albo-atrum produced resting dark mycelium. Optimum temperatures for mycelial growth of V. dahliae and V. albo-atrum on PDA were 22 and $26^{\circ}$, respectively. Mycelial growth of V. albo-atrum was slower than that of V. dahliae. Pathoge-nicity tests revealed that tomato cvs. Zuikoh No. 102, Kyoryokubeiju No. 2, Zuiken, Kagimuza, and Momotaro were susceptible to V. albo-atrum, while cvs. Zuikoh No. 102 and Kyoryokubeiju No.2 were susceptible to V. dahliae.