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Rhizoctonia damping-off in Sesame.

Authors:  M.A. AL-Hamdany and M.M. Salih

Citation: 1986. Indian Phytopathology, 39: 124-126.

Abstract:

ٍ                                  Seventeen fungal isolates were isolated from sesame diseased plants were tested for their pathogenicity on sesame cultivar I539.During the first 10 days, 48.8% of sesame was killed before emergence. However, the total loss (pre- and post-emergence) was 57.4, 76.0, 83.0, 86.0, 90.0 and 90.6% recorded at 20, 30, 40, 50, 60, and 70 days after planting respectively. Meanwhile, all the sesame mutant (N, L, G, H, E) and two cultivars (local and I539) showed susceptible reactions. Total loss percent after 40 days was 75.11, 75.90, 88.24, 87.88, 70.00, 67.08, and 88.35, respectively. As a result of culturing all diseased seedlings on PDA, Rhizoctonia solani (5 isolates), Ceratobasidium cornigerum, Macrophomina phaseolina (2 isolates), Fusarium solani (3 isolates, F.oxysporum, F.equiseti, F. semitectum (2 isolates), and F. moniliforme (2 isolates) were isolated. The pathogenicity test of all these isolates revealed significant differences in their relative virulence. The results showed that R.solani is the major pathogen of damping off, while Macrophomina and Fusarium could be considered as minor pathogens. However, damping off incidence was significantly increased when Rhizoctonia was added to them separately or together. In the control, seedling mortality (14%) could be attributed to Macrophomina and Fusarium since both of them were often isolated from the seeds. Thus, it is very likely that R. solani was overlooked in previous investigations. Although M. phaseolina has been emphasized in screening for resistance to charcoal rot, Rhizoctonia should be considered in any screening programme for disease resistance in sesame.                                            

Key words: Sesame, wilt, damping-off, Rhizoctonia solani