Location: Foreign Disease-weed Science ResearchTitle: Leaf anthracnose, a new disease of swallow-worts caused by Colletotrichum lineola from Russia Author
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2011
Publication Date: 12/1/2011
Citation: Berner, D.K., Cavin, C.A., Mukhina, Z., Kassanelly, D. 2011. Leaf anthracnose, a new disease of swallow-worts caused by Colletotrichum lineola from Russia. Plant Disease. 95:1586. Interpretive Summary: Black swallow-wort and pale swallow-wort are invasive plants and are targets of biological control efforts to control their spread in the USA. In 2010, diseased leaves of a related plant were collected in the Krasnodar area of Russia and sent to the BSL-3 containment facility at the Foreign Disease-Weed Science Research Unit (FDWSRU) of the USDA/ARS in Frederick, Maryland. A fungus was collected from the leaves, and plants of black and pale swallow-wort, as well as plants from Russia, were sprayed with spores of the fungus. Two weeks later, the fungus was recovered from 12 of the 13 plants that had been sprayed. Spores of the fungus matched the description of Colletotrichum lineola. DNA sequences matched 100 percent to DNA of 15 other collections of C. lineola in the National Center for Biotechnology Information GenBank collection. Specimens of the fungus have been deposited in the U.S. national fungus collection. Further tests are planned to determine the suitability of the fungus for biological control of swallow-worts in the U.S.
Technical Abstract: Black swallow-wort Vincetoxicum nigrum (L.) Moench and pale swallow-wort Vincetoxicum rossicum (Kleopow) Borhidi (family Apocynaceae subfamily Asclepiadoideae) are invasive plants and are the targets of biological control efforts to control their spread in the USA. In 2010, diseased leaves of a related species, V. scandens Sommier and Levier, were collected in the Krasnodar area of Russia and sent to the BSL-3 containment facility at the Foreign Disease-Weed Science Research Unit (FDWSRU) of USDA/ARS in Frederick, Maryland. Pure cultures (FDWSRU 10-002) were obtained from the fungus isolate and seeds of V. scandens, collected simultaneously in Russia, were germinated and transplanted in a 20 degree C greenhouse under 12 hours of light. Two-month-old plants each of V. scandens, V. nigrum, and V. rossicum were inoculated with spores from two-week-old cultures of isolate 10-002. Two weeks later, the fungus was re-isolated from 7 out of 7 inoculated V. scandens plants, 1 out of 2 V. nigrum plants, and 4 out of 4 V. rossicum plants. Conidiophores were brown, septate, and branched. Lengths of the conidia conformed to the description of Colletotrichum lineola Corda, but the conidia were slightly narrower than described. Appressoria also conformed to the description of appressoria of Colletotrichum lineola Corda. DNA sequences of ITS1, 5.8S, and ITS2 (GenBank # HQ731491) aligned 100 percent to 15 isolates of C. lineola in GenBank. Voucher specimens of the fungus have been deposited in the U.S. national fungus collection. Host-range and efficacy tests are planned to determine the suitability of C. lineola for biological control of swallow-worts in the U.S.