Tea (
Camellia sinensis
) is a major source of foreign exchange in Kenya. Its production is greatly affected by the stem canker disease (
Phomopsis theae
) and, thus, the need to develop effective control strategies. The efficacy of three fungicides (copper oxychloride, mancozeb and benomyl at concentrations of 10, 25, 50, 100 ppm for each, and acqueous leaf extracts (10% w/v) of four indigenous plants, sage brush (
Lippia javanicum
), stinging nettle (
Urtica massaica
), savory (
Satureia biflora
) and Kenya green heart (
Warburgia ugandensis
) were evaluated in vitro against two isolates (P 228 and P 794) of
Phomopsis theae Petch, the cause of stem canker disease of tea. The variables used for the study of growth inhibition were colony diameter and number of pycnidia produced on malt extract agar, and dry weight of thallus biomass in liquid malt extract. The three fungicides differed significantly (P<0.01) from each at all concentrations. Benomyl was the most effective as it completely inhibited the two isolates of
P. theae in all concentrations. Mancozeb was the next best but it was effective only at high concentrations. Copper oxychoride was found least effective even at high concentrations. Aqueous leaf extract of
W. ugandensis was the most effective and completely inhibited mycelial growth, biomass accumulation and pycnidial production even at very low concentrations.
