|Keywords (Extracted from title, table of contents and abstract of thesis)
fungi, seed-borne diseases, wheat, rice, fungicides, ustilago tritic, urocystis tritic, loose smut of wheat, flag smut of wheat, karnal bunt, neovossia indica, stinking smut, ti11etia foetida, fusarium spp., alternaria sp., drechs1era spp.
Wheat and rice fields of Pakistan were extensively surveyed during 1986-89 for important seed-borne diseases. Of the major seed-borne diseases, loose smut of wheat (Ustilago tritic) and flag smut of wheat (Urocystis tritic) were widely prevalent in all the four provinces of Pakistan; partial bunt or karnal bunt (Neovossia indica) in the central, northern Punjab and NWFP whereas complete bunt or stinking smut (Ti11etia foetida) was confined in the uplands of Balochistan and hilly areas of Punjab and NWFP. In the non-irrigated areas Fusarium spp., and in irrigated areas Alternaria sp., and Drechs1era spp., were associated with seed rot, foot rot and seedling blight of wheat. Of the seed-borne diseases of rice, blast disease of rice (Pyricu1aria oryzae) was a major disease in the central the arts of Punjab and a minor disease in Sindh, brown leaf spot of rice (Drechs1era oryzae)and kernel bunt of rice and barc1ayana) were prevalent in all the rice growing areas of Pakistan Using standard blotter, agar plate and deep freezing methods, 17 genera and 40 species of fungi Were isolated and identified from 450 seed samples of wheat and 26 genera and 54 species of fungi from 200 seed samples of rice. The occurrence 01 23 species of fungi viz., A1ternariagodetide A. raphani, Aspergillus candidus6 A. sulphureus, A. tamarii, A. terreus, Cephalosporium graminearum, Chaetomium crispatum. c.funicola, Cladosporium spherospermum, Curvularia clavata, c. robusta, Drechslera rostrata, Epicoccum purpurascens, Fusarium equiseti F. graminearum, F. nivale, Melanospora zamiae, Hemnoniella echinata, Myrothecoum roridum, Pencillium purpurogenum, Sporotrichum purinosporum and Stachybotrys atra on wheat seeds and 31 species of fungi viz., Alternaria lonqipes, A. raphani, Aspergillus candidus, A. sulphureus, R. terreus, Botrytis atra, Cephaliophora irregularis, Chlalaropsis thielavioides, Curvularia clavata, c. eragrdstidis, C. in termedia , C. penniseti, C. tuberculata, Drechslera australiensis, D. biseptata,D.ha I odes ,D.rostrata, D. specifera, Fusarium avenaceum, F nivale F. semitectum, Helicodendron paradoxum, Memnoniella ecninata, Myrothecium roridum, Penicillium purpurogenum, Pithomyces graminicola, Stachybotrys atra, S. dichora, Staphylotrichum cocosporum, Tetraploa ellisii and Trichothecium rosem On rice seeds are being reported for the first time from Pakistan. Of the different isolation techniques used, blotter method proved better for quantitative analysis and agar plate method for qualitative analysis of seed-borne fungi. Alternaria spp., and Fusarium spp., were conveniently isolated by blotter method and species of Curvularia and Drechslera by agar plate method. The deep freezing method was found more effective for the isolation of deep seated seed-borne fungi like Drechslera oryzae, Gerlachia aryzae, Fusarium moniliforme, Trichoconis padwickii and Drechslera soroliniana.