Location: Foreign Disease-Weed Science
Title: First report of leaf spot of Convolvulus arvensis caused by Phoma macrostoma var. macrostoma in Turkey Authors
Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2014
Publication Date: July 1, 2014
Citation: Tunali, B., Cavin, C.A., Berner, D.K. 2014. First report of leaf spot of Convolvulus arvensis caused by Phoma macrostoma var. macrostoma in Turkey. Journal of Plant Pathology. 96:434. Interpretive Summary: Field bindweed (Convolvulus arvensis L.) is an exotic perennial vine that is invasive in the USA and problematic in Turkey. In May 2012, diseased C. arvensis plants were found near Ondokuz Mayis University, Samsun, Turkey. All of about 40 plants (vines) in the area were diseased. Symptoms were irregular tan-colored necrotic lesions on leaves. Symptomatic leaves were sent to the USDA, ARS, Foreign Disease-Weed Science Research Unit plant pathogen containment facility, at Ft. Detrick, MD. A fungus identified as Phoma macrostoma var. macrostoma was isolated from these leaves, and the disease was reproduced with the fungus on field bindweed plants. Specimens of the fungus were deposited in the U.S. national fungus collection. Further tests are planned to determine the suitability of the fungus for biological control of field bindweed in Turkey and the U.S.
Technical Abstract: Field bindweed (Convolvulus arvensis L.) is an exotic perennial vine that is invasive in the USA and problematic in Turkey. In May 2012, diseased Convolvulus arvensis plants were found near Ondokuz Mayis University, Samsun, Turkey. Symptoms were irregular tan-colored necrotic lesions on leaves. Leaves with lesions were surface disinfested for 5 min. in 10 percent bleach followed by incubation at 20-25 degrees C in moist chambers. Pycnidia developed after 5-7 days, and pure cultures were obtained by transferring conidia from pycnidia onto oatmeal agar. Colonies were peach-colored, and did not change color with the addition of NaOH. Pycnidia in culture were scattered, globose, 119.6 µm in diameter, with one papillate ostiole measuring 29.7 µm diam. (average), with glabrous and elongated necks (average 199.5 µm long). Conidia were aseptate, hyaline, ellipsoidal to oblong, (mean 8.1 × 2.7 µm). These characters matched the description of Phoma macrostoma Mont. var. macrostoma (Boerema et al., 2004). A specimen was deposited with the U.S. National Fungus Collections (BPI 892537). DNA sequences for the internal transcribed spacers (GenBank #KC590613) aligned, after BLAST analysis, 97 percent to 10 identified isolates of P. m. var. macrostoma and 99 percent to 2 isolates of P. macrostoma. Conidia were spray-inoculated, in a suspension of 106 conidia ml-1, onto twenty 30-day-old C. arvensis plants; another ten control plants were sprayed with water only. Plants were placed in dew at 25 degrees C for 40 hours and then moved to a 20-25 degrees C greenhouse. All inoculated plants became diseased; no control plants became diseased. P. m. macrostoma was re-isolated from all inoculated plants. To our knowledge this is the first report of P. m. macrostoma from Convolvulus arvensis.