BIOLOGICAL STUDIES ON SOME FUNGI ASSOCIATED WITH SUNFLOWER IN PAKISTAN

To know the seed mycoflora of sunflower, 196 seed samples were collected from rent sources and tested using blotter paper method. Twenty fungi normally considered ogenic to oil seed crops, were recorded. Out of these, Alternaria helianthi, chslera hawaiiensis, D. longirostrata, Fusarium culmorum, F. oxyporum, pthecium hawaiiensis, D. longirostrata, Fusarium culmorum, F. oxysporum, * pthecium roridum, M. verrucaria, Phoma oleracea, Phomopsis helianthi, *phylium helianthi and Verticillium dahliae were the new record for Pakistan on lower seeds. High incidence of A. alternate and F. moniliforme, was observed * web by F. semitectum, Emericellopsis terricola, Macrophomina phaselina, S. * nthi and others. More open pollinated varieties were found infected than the * ids.\ud \ud \ud To study the relationship of seed mycoflora with prevalence and incidence of lower field diseases, a systematic survey was carried out in various agro-ecological * ons of Pakistan during 1991. A total of 10 diseases were recorded. Alternaria leaf spot * charcoal rot were observed with highest incidence at maximum localities followed * ead rot, Phomosis leaf spot collar rot, Phomosis leaf spot and Phoma leaf spot / black stem rot. A higher number of lower cultivars were observed infected with charcoal rot and Alternaria leaf spot web by the head rot, collar rot and others.\ud \ud \ud No new disease was observed during current survey but prevalence, incidence and * rity of already known diseases showed and upward trend. A part from charcoal rot and * rnaria leaf spot, powdery mildew and bacterial rot were found emerging pathological * lems. All the field diseases observed in current survey are known to be seed * mitted. The casusal organisms of five field diseases, namely Alternaria leaf spot, coal rot, head rot, Phoma leaf spot / black stem rot and Phomosis leaf spot were * d to be associated with seed and were analyzed for seed mycoflora.\ud \ud \ud A study on the pre-treatment with mercuric chloride showed that number of seed-*e fungi remained the same but their incidence decreased. It indicated that these fungi* ternally seed-born and not surface contaminants. A study was conducted to know * ect of mycoflora on germination of sunflower seed. It was found that seed-borne caused abnormalities reaching 25%. In Pathogenicity test, 15 fungi were to be pathogenic on sunflower plants. D. hawaiiensis, D. longirostrata, D. * era. E. terricola and M. verrucaria failed to cause infection on sunflower plants in vitro conditions. For successful detection of seed-borne fungi, blotter paper * I was found most suitable, simple less time consuming and economical as red to agar plate, anchor and dry inspection methods.\ud \ud In the study pertaining to location of major seed-borne fungi in different seed * nents, A. alternata and M. phaselina were found in the pericarp, endosperm and *o. In transmission studies of these pathogens, the dying seedlings yielded * nata 90% from hypocotyls and cotyledons. M. phaseoline caused pre* ence death of seedlings and post emergence mortality in the form of damping off, * t and root and stem rot between fourth and eight week of growth. In a correlation from seed a field infection, it was concluded that 10% infection due to * nata and 5% of M. phaseolina in the seeds, can safely be used for sowing.\ud \ud The produce of sunflower kept in storage for extension of oil, were tested for * e fungi. Nineteen seed – borne fungi were detected. The highest seed recovery was of * aria, Aspergillus, Rhizopus and Fasurium spp. These fungi are known to be * ed in production of various mycotxin. Higher incidence of seed mycoflora * sed the quantity of oil and unsaturated fatty acids but increased the saturated fatty oncentration. A seed treatment study was carried out to minimize the seed – borne and subsequently field diseases. Seed treatment with Tecto, Benlate and seed * ntes viz, Azadirachta indica and Coriandrum sativum gave best control and * sed the germination of sunflower. These results indicate that seed diffusates can * I the sunflower diseases caused by seed – borne pathogens under field conditions and substitute the expensive chemicals used for the same purpose in a more healthy and * ly environment