Canker and wilt of black locust (Robinia pseudoacacia L.) caused by Fusarium species.

From the pathological material of black locust trees showing symptoms of wilting of the foliage or canker of the bark the following Fusarium species were isolated: Fusarium avenaceum (Fr.) Sacc., Fusarium lateritium Nees., Fusarium semitectum Berk. & Rav., Fusarium solani (Mart.) Sacc., Fusarium sulphureum Schlecht. (syn.: Fusarium sambucinum Fuckel f. 6 Wollenw.) The results of the provocation infections of one-year-old black locust seedlings showed that all of the species--except Fusarium solani--are able to cause considerable necrosis in living bark and phloem. Fusarium sulphureum had by far the highest pathogenecity among the tested species. Fusarium semitectum isolated from withered black locust tree also caused necrosis on significant bark area. In the course of the penetration assay Fusarium sulphureum and Fusarium avenaceum were the most successful, and these species can cause cankers on the stem and twigs of black locust without frost effect.