وقوع بيماري لكه قهوه اي نارنگي پيچ در غرب استان مازندران

Occurrence of brown spot disease of page mandarin in west of Mazandaran

During 2002-2003, a survey was conducted in citrus orchards in west of Mazandaran. A disorder was observed on fruits, leaves and twigs of panne mandarin Citrus reticulata (Minneola tangelox Clernentina). Young fruits and leaves mostly drop. The remained fruits on trees have low quality. In order to identify the causal agent of the disease, symptomatic leaves, twigs and fruits were collected from orchards and surface disinfected with hypochlorite sodium. Samples were cultured on PDA and incubated in 27"C for 7 days. Purification was done by single spore on water agar. Fungal colony had an olive green to dark brown colour and 15-25 mm growth mean per day. Conidia had different size, 1-7 wall length and 1-5 septums. Pathogenicity tests were carried out by using the spore suspension and fungus disk on detached leaf and fruit in a container with humid condition in room temperature. Most of isolates induced brown spots on leaf and fruit of page mandarin, while there is not any symptom in the treatments with distilled water in the same condition. ʹI he pathogen of brown spot reisolated from infected tissues. According to morphological characteristics and references the cause of disease was identified as Alternaria alternota PV. Citri This is the First report of the occurrence of brown spot of page mandarin in Iran.