A New Powdery mildew of Malvapusilla

摘要

During a general survey, a new powdery mildew disease was recorded on Malva pusilla (Malvaceae) around University campus Raipur. The samples showing the powdery mildew symptom were collected and examined for the identity under microscope. The standardsystem of characterization of powdery mildew fungi were made using Blumers (1967) conidiophore-type based on the Brundza (1933) and "A" and "B" units of conidiophore in the sense of Hammet and Manners (1973). The samples were submitted to HCIO, New Delhi for deposition. On the basis of morphology the fungus has been identified as Sphaerotheca fuliginea (Schlecht.: Fr.) Poll. Mycelium amphiphyllous, hyphae upto 9.12 mu m in diam., appresoria nipple shaped. Conidiophores euoidium type, mostly slightly curved sometimes straight, A & B units of 2 to 8 cells, 111.24-185.4 X 12.77-17.71 u m, av. 148.04 X 16.23 u m., foot cell 41.2-78.28 X 10.71-16.48 u m, av. 54.65 X 12.52 mu m. Conidia broadly ovate 28.84-41.2 X 16.48-20.6 mu m, av.32.61 x 18.78 mu m. Germtube lateral 1-2, cylindric to fusiform. It was also observed that the conidiophore of the fungus was found to be heavily hyperparsitised by the Ampelomyces quisqualis. But the infestation of Ampelomyces varied from one locality to another in the same period. In case of severe infestation it suppresses the formation of conidiophore and conidia on the leaves of host plant and only superficial thin coating of powdery mass was recorded instead of the thick powdery mass recorded on other plants free from Ampelomyces.