• A Ramalingam

      Articles written in Proceedings – Plant Sciences

    • Epidemiology of sorghum downy mildew. II. Circadian and seasonal periodicities in conidia and oospores

      M M Shenoi A Ramalingam

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      This paper reports on the epidemiological studies undertaken on the airborne diseases of sorghum at Mysore including the downy mildew. The circadian and seasonal periodicities are presented and the significant reversal of usual role of conidia and oospores normally found in Peronosporaceae is discussed.

    • Hazardous species ofAspergillus ochraceus group in the air of working environments at Mysore

      K B Jayaprakash A Ramalingam

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      Species of theAspergillus ochraceus group were most abundant in the air of a coffee curing works of the seventeen environments studied at Mysore. They also occurred in large numbers in coffee dust, husk samples, sorghum and paddy. Incubating at room temperature (20–25°C) was found most suitable for enumeration of these species. Only 6.6% of the air-borne isolates of the group produced ochratoxin-A. A. ochraceus was the most common species of the group isolated from air and also yielded a greater proportion of toxic isolates.

    • Wind-tunnel estimation of fungi colonizing sorghum seed from field to storage

      P Shankara A Ramalingam

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      Microbial loads of sorghum seeds were estimated using a wind tunnel at 3 successive stages; mid ripe, threshing and storage. Very high concentration of field fungi viz.,Curvularia, Drechslera, Fusarium, Phoma andSphacelotheca sorghi were recorded from seeds at threshing stage, whereas their populations decreased during storage. Storage fungi such asPenicillium andAspergillus increased considerably after storage. High concentration of microbes were released even with least agitation.

    • Splash dispersal inRamulispora sorghi Olive and Lefebreve, the casual organism of sooty stripe of sorghum

      A H Rajasab A Ramalingam

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      The conidia ofRamulispora sorghi were produced in a mucilaginous mass and dispersed through splash-off and wash-off mechanisms during rain, while the sclerotia ofRamulispora sorghi were produced freely and attached superficially to the host leaf surfaces, dispersed through air over short distances and deposited on the sampling surfaces at the rate of 22 sclerotia/cm2/day.

      Greater number of conidia were monitored by splash traps during the kharif crop period as compared with that of rabi. The peak conidial dispersal was noticed during the 10-leaf stage—flag leaf growth stages of sorghum crop. Both incident water drops (splash-off) and flowing water drops (wash-off) liberated the conidia from the sporulating lesions. Peak liberation of conidia occurred with the water drops from 3–7 and most conidia were removed from the sporulating lesion within 60 s indicating the possible dispersal of the pathogen even during short traces of rain.

    • Splash dispersal inColletotrichum graminicola (Ces.) Wilson, the causal organism of anthracnose of sorghum

      A H Rajasab A Ramalingam

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      The conidia ofColletotrichum graminicola (Ces.) Wilson were dispersed only by rain drops. The dispersal was related to the frequency of rainfall. Under field conditions, conidia were dispersed vertically up to a height of 0·75 m and laterally up to a distance of 1 m from the source. Both incident water drops and flowing water liberated conidia from the sporulating lesions. Peak liberation of conidia occurred with the water drops 3–11, and most conidia were removed from the sporulating lesions within 60 s, suggesting dispersal of the pathogen even during small showers of rain.

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