ARS | Publication request: Leaf anthracnose, a new disease of swallow-worts from Russia

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: March 9, 2011
Publication Date: June 1, 2011
Citation: Berner, D.K., Cavin, C.A. 2011. Leaf anthracnose, a new disease of swallow-worts from Russia. American Phytopathology Society. 101:S272.

Technical Abstract: Black swallow-wort Vincetoxicum nigrum (L.) Moench (synonym=Cynanchum louiseae Kartesz & Gandhi) and pale swallow-wort Vincetoxicum rossicum (Kleopow) Borhidi (synonym=Cynanchum rossicum (Kleopow) Borhidi) are invasive plants belonging to the family Apocynaceae 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 & Levier, were collected in the Krasnodar area of Russia and sent to the BLS-3 containment facility at the Foreign Disease-Weed Science Research Unit (FDWSRU) of USDA, ARS in Frederick Maryland. Surface disinfested leaves were placed in sterile moist chambers, and, after several days at 20-25 degrees C, acervuli formed on irregular tan necrotic lesions. Pure cultures (FDWSRU 10-002) were obtained by transferring spore masses with sterile glass needles onto 20 percent V-8 juice agar. Seeds of V. scandens, collected simultaneously in Russia, were placed in a freezer at -20 degrees C for 6 weeks and then germinated in sterile Petri plates on moist filter paper. The seedlings were then transplanted and grown in a 20 degrees C greenhouse under 12 hours of light. Five 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. Plants were inoculated by spraying an aqueous suspension of 106 spores per ml onto each plant until all leaves were wet. The plants were placed in 20-24 degrees C dew chambers for 18 hours and then placed in a 20 degrees C greenhouse. Two weeks later, diseased leaves of each species were harvested, and the fungus was re-isolated from each species. Spore and appressoria measurements conformed to the description of Colletotrichum lineola Corda, and ITS sequences of this isolate (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.