Studies on Colletotrichum acutatum in Israel
Strawberry anthracnose caused by Colletotrichum acutatum (EU Annex II/A2) was first observed in Israel in 1995, and reached epidemic levels in 1995-96. In a majority of cases typical symptoms of crown rot, flower blight, fruit rot were observed, except in at least four production fields of the same region where plants showed stunting and chlorosis. When uprooted, most of them presented decayed roots of a dark brown colour. Studies were carried out to characterize 147 isolates from plants showing typical and atypical symptoms by using isolation methods on semi-selective medium, pathogenicity tests, vegetative compatibility tests and PCR. C. acutatum was isolated from both type of plants. Both foliar and root-infecting isolates were equally pathogenic to strawberry. Results of the vegetative compatibility tests showed that most isolates (113 out of 115 tested isolates) belonged to a single vegetative compatibility group. Finally, when compared to US isolates of C. acutatum by using PCR techniques, similarities were observed. The authors felt that this suggests that the Israeli isolates belong to an asexually reproducing clonal population which may originate from USA. They also noted that under certain conditions (e.g. climate, high inoculum pressure etc.) the pathogen can also cause severe stunting and death of strawberry plants by infecting the root system.
Sources
Freeman; S.; Katan, T. (1997) Identification of Colletotrichum species responsible for anthracnose and root necrosis of strawberry in Israel.
Phytopathology, 87(5), 516-521.