CHOANEPHORA BLIGHT: A NEW DISEASE OF LABLAB BEAN (LABLAB PUPUREUS) IN BANGLADESH
M. E. Rahman, M. M. Islam, M. E. K. Chowdhury, M. M. Rahman and T. K. Dey. 2012. Choanephora blight: a new disease of lablab bean (Lablab pupureus) in Bangladesh. Bangladesh J. Plant Pathol. Vol. 28 (1&2): 67-68.
A new disease of country bean (Lablab pupureus) caused by Choanephora cucurbitarum appeared in the districts of Gazipur, Pabna, Bogra and Jamalpur districts of Bangladesh. Initial symptoms of the disease were recognized as small water soaked lesion on leaves. The lesions enlarged gradually covering large areas. Infected parts dried up with age showing blight symptoms. Blossoms and twigs were also infected. Dieback of vine and black soft lesions on young pods appeared with the progress of time. Mycelia and sporangiola of the causal fungus appeared on infected leaves, blossoms and pods as numerous black spore-bearing structures, sporangia. The causal pathogen of the disease was isolated and its morphological characters were studied and it was identified as C. cucurbitarum.
Country bean (Lablab pupureus) is a widely grown leguminous vegetable crop in Bangladesh. The crop is attacked by at least six plant pathogens in the country (Talukder 1974, Ahmed 1985). A new disease of the crop appeared on this vegetable in the districts of Gazipur, Pabna, Bogra and Jamalpur in Bangladesh. The disease was characterized by the appearance of blighted leaves and blossoms, dieback of vine tips, and black and soft rot lesions on fruit (Plate-I). Initially the symptoms appeared as water soaked lesions, which enlarged, became dark and the infected parts dry up with age. Infected plant with die-back symptoms (Plate-I-A) and black and dry lesion were observed on young branch (Plate-I-B). Structures of the causal fungus appeared on both surfaces of the leaves, blossoms and pods as numerous black spore-bearing structures, giving the appearance of “whiskers”(Plate-I C & D). Whiskers of the fungus, which are fungal strands consists of dark colored knobby sporangiola.
Infected leaf and fruit samples were collected and associated fungal pathogen was isolated following tissue planting method on potato dextrose agar (PDA)
medium (Mian 1994). Off – white to yellowish white and fuzzy growth of the fungus appeared on PDA (Plate-I E). Morphological characters (Plate-I F) of the associated fungus were studied and it was identified as Choanephora cucurbitarum (Berk. & Rav.). The available literature (Bakr, 2007, Talukder 1974) reveal that the fungus has not been reported earlier on this host from Bangladesh. Therefore, it is a new record of the disease of country bean in the country.
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