Effects of botanical fungicides on seed storage fungi of yemane (Gmelina arborea Roxb.)

Two species of saprophytic fungi were isolated from yemane seeds. These were identified as Aspergillus niger Van Tieghem and Botryodiplodia theobromae Pat. Of the seven known botanical fungicides tested in vitro, concentrated crude extracts of the five species namely: Kakawate, neem, garlic, akapulko and tobacco exhibited fungitoxic effects against A. niger. Extracts from akapulko, tobacco and rosal inhibited the growth of the fungus one day after disc planting while neem extract remained active until two days after disc planting and kakawate extract for three days after disc planting. Garlic remained active until ten days after disc planting similar to the commercial fungicide (Dithane M-45). Extracts from kakawate, neem, akapulko and tobacco were effective against B. theobromae for only one day after disc planting; ipil-ipil, three days after disc planting. Garlic was effective up to ten days after disc planting better than Dithane M-45 which was effective only for four days. Garlic proved to be the most stable and most effective over the other plant extracts tested in inhibiting fungal growth in vitro. Garlic extract was effective as Dithane M-45 in controlling growth of A. niger and was effective against B. theobromae. Seeds treated with Dithane M-45 showed the highest mean percent germination (50.43) but was not significantly different from that of seeds applied with garlic powder at 15 g/kg seeds (49.04). The respective mean percentages of seeds treated with garlic powder at 5 g/kg seeds (39.70) and 10 g/kg seeds (41.13) were not significantly different from that of untreated seeds (37.80). Germination percentages for all treatments were significantly reduced with prolonged storage. No significant differences was observed on the moisture content percentages of treated and untreated seeds during the six months observation period. Garlic applied at a rate of 15 g/kg seeds could be used as a substitute seed protectant of yemane seeds. Histopathological study revealed the presence of massive mycelial growth embedded within the seed coat and inner tissues of infected yemane seeds that caused cell wall degradation