Leaf Die-back of Date Palm as Caused by Nattrassia mangiferae in Kerman Province

Numerous date palm orchards in south Kerman, Iran were investigated during 2001-2003. Symptoms of leaf die-back appeared as light brown stripes which began at leaf tips and extended to leaf ends. Infected tissues were surface sterilized with 0.05% sodium hypochlorite and, plated on PDA medium. Isolated fungi were purified using hyphal tip method. On PDA medium, fungal colony was fluffy, first colorless and then changing into dark brown. Arthroconidia were in general one celled of spherical to ellipsoid shape. Conidiomata were rarely formed in culture but pycnidia did form on the host plant. To test pathogenicity, after surface disinfestaion using ethanol 70%, the epidermal layer of the leaf rachis as well as that of bunch stalk were removed using a sterile scalpel. Three to four mycelial disks of 7 day old fungal colony were placed under the layer and covered by wet cotton and parafilm tape. PDA medium was employed for inoculation of control plant. Five to seven days after inoculation, brown necrotic lesion appeared. No symptom was observed in control. Inoculated fungus was recovered from the infected plant. On the basis of the mentioned morphological characters and pathogenicity test, the fungus was identified as N. mangiferae. This is the first report of date palm leaf die-back on Barhee, Kabkab, Mazafati and Zahedi cultivars in southern Kerman, Iran.