Abstract
Pycnidial formation starts six days after inoculation. These arę globose, dark and range between 59.28-109.20 μm in diameier. The pycnidial wall is composed of 2- 3 layers of brown cells. The pycnidiospores ooze 8 days after inoculation. They are filiform, straight to curved, hyaline, septate with 2-4 septa, ends pointed or round and 21.84-68.64 x 1.25-2.15 μm. Mycelial growth was most profuse on Czapek Dox's agar medium, whereas maximum sporulation took place on Coon's, Sabauraud's and Potato dextrose agar media. The fungus could grow over a wide range of temperature from 12- 36°C (optimum: 24 ± l°C) and showed no growth at 40°C or above. Pycnidial formation occurred at 16- 28°C with a maximum at 24 ± l°C. Out of seven carbon sources tested, sorbose was the best for growth and sporulation of Septoria vignicola whereas maltose was a poor source for sporulation. The fungus responded very well to the supply of carbon in culture media as no growth of the fungus could be observed when the carbon supply was with held. Aspartic acid supported optimum growth among all the organic sources tried, whereas among inorganic sources potassium nitrate was the best, last growth observed on ammonium nitrate.
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