Poster Session: New and Emerging Diseases-Fungi and Oomycetes

417-P

First report of Cryphonectria parasitica on chestnut in Lebanon.
A. T. SAAD (1), M. Temsah (2), L. T. Hanna (1)
(1) American University of Beirut, Beirut, Lebanon; (2) Biology Department, Lebanese University, Beirut, Lebanon

Chestnuts Castanea sativa have long been cultivated on a limited scale in Lebanon. During the last ten years, however, chestnut plantings have been gaining importance on the sandy mountainous areas over 1200 meters above sea level. Last summer, growers reported the death of new plantings as well as deterioration in the health of the older chestnut trees. Affected chestnut trees showed dieback symptoms and sunken stem cankers of various sizes on the main trunks and limbs, with yellow to orange blisters. Tissues beneath the upper surface of the cankers were dead, sometimes with mycelial mats. Laboratory examinations of affected tissues revealed the presence of scattered or aggregated yellow to buff colored unilocular or complex multilocular pycnidia embedded in the bark tissue that has become particularly spongy. The conidiophores were hyaline, septate and branched. The conidia (3x1.5µm) were hyaline, unicellular, and ellipsoidal in shape. The perithecia were seen immersed in the stromatic tissues, in aggregates and were mostly oblique. Perithecia were dark brown to black, globose (300-400µm in diameter), slightly depressed with long ostiolar necks up to 800µm long and 200µm wide at the base. Ascospores (9-12x3-5.5 µm) were hyaline, two celled, rounded at their ends, smooth and slightly constricted at the septum. This is the first report of the occurrence of the quarantine chestnut blight disease in Lebanon.