Seed-borne fungi of common vegetables and their role in causing seedling diseases

Abstract

A number of fungi were found associated with vegetable seeds, both externally and internally, during the present study. This include nine species of Fusarium, eight species of Aspergillus, four species each of Chaetomium and Penicillium. Other fungi like Corynascus sepedonium, Curvularia clavata, Gilbertella persicaria, Gonatobotryum apiculatum, Humicola fuscoatra, Paecilomyces inflatus, Rhizopus oryzae, Scytalidium sp., Syncephalastrum racemosum, Talaromyces flavus and Zopfiella Karachiensis were also found to be seed-borne in vegetables. In amaranthus, Fusarium sp. 3 caused significant inhibition of germination and significant incidence of damping off. In chilli, Aspergillus flavus was found to be a serious seed- borne fungus while in tomato Penicillium purpurogenum caused considerable inhibition of germination of seeds as well as incidence of damping off of its seedlings. Fusarium pallidoroseum, Chaetomium brasiliense, Gilbertella persicaria and pericillium sp. Were found to be serious pathogens in snake gourd. Culture filtrates of most of the fungi tested during the persent study caused significant inhibition of germination of seeds, inhibition of elongation of plumule and radical, and wilting of seedlings of the corresponding vegetables. While most of the culture filtrates were found to be thermostable, culture filtrates of some of the fungi lost their toxicity by boiling. When the inhibitory effect of different seed treatment fungicides against different seed-borne fungi was studied, Luzem 45 (mancozeb) was found to be the best one and it could completely inhibit the growth of nine species of fungi at the minimum concentration tested. Hexacap (captan) was ranked second while Blue copper 50 (copper oxychloride) was found to be the least effective fungicide in inhibiting the growth of different seed-borne fungi. When the different seed treatment fungicides were tested for their efficacy in increasing the germination of seeds and decreasing damping off of seedlings, Hexacap treatment had shown maximum effect in all the vegetable tested. The other fungicides in the order of their efficacy were Bavistin and Luzem 45. When the mean value of effect of different fungicidal seed treatment methods were compared, slurry treatment was found to be the best in case of amaranthus, and chilli while dry treatment gave maximum effect in tomato, ash gourd and snake gourd.