In Vitro Response Of Phomopsis Theae To The Products Of Azadirachta Indica And Extracts Of Warburgia Ugandensis

ABSTRACT

Tea is one of the major cash crops in Kenya and a means of livelihood to people living around the region where it is grown. Branch and collar canker disease is among the many diseases which affect the crop hence reducing its production. Methods used to control the disease mainly involve the use of chemical fungicides which are toxic and not environmentally friendly. This study was therefore done to determine the use of plant products and extracts to manage the disease. Among the products used were Nimbecidine and Trilogy which are products of neem tree. The Warburgia ugandensis extracts from the bark, root and leaf were also used in vitro to determine the inhibition of Phomopsis theae the causative agent of Branch and Collar Canker. These were compared with the inhibition of standard fungicides (Topsin and Saaf). Nimbecidine and Trilogy were also tested at the concentration of 10 ppm, 25 ppm, 50 ppm and 100 ppm, while W. ugandensis extracts were tested at the rates of 10 g/100 ml, 15 g/100 ml and 20 g/100 ml. Nimbecidine inhibited growth more than Trilogy in all the concentrations and were not significantly different from those of Topsin and Saaf. Stem bark extracts of W. ugandensis were also effective in inhibiting the growth of P. theae with inhibition of 97.64 per cent in all the rates. Root was next in inhibition with 78.8, 19.45 and 9.89 per cent in 20 g, 15 g and 10 g respectively. The leaf extracts did not inhibit growth at any rate. In liquid media, similar results were observed. In Nimbecidine, mycelial weights were significantly lower compared to Trilogy. Stem bark extracts also had lower mycelial weights, followed by the root and then leaf among the extracts. Nimbecidine and bark extracts of W. ugandensis were compared with standard fungicides, Topsin and Saaf, and the extract was comparable to the fungicides both in solid and liquid media. They were able to inhibit the growth of P. theae.