A study was undertaken on the effectiveness of some fungicides such as wettable sulphur, copper hydroxide, potassium bicarbonate and potassium bicarbonate mixed with potassium silicate against apple scab and apple powdery mildew attack, in the environmental conditions of Cluj-Napoca, Romania. The following cultivars were analyzed ‘Jonathan’, ‘Gala’, ‘Jonagold’, ‘Jonica’, ‘Golden Delicious’, ‘Idared’, ‘Granny Smith’ and ‘Starkrimson’, in an experiment conducted over two growing seasons (2009-2010), in five treatment variants. Potassium bicarbonate and a mixture between potassium bicarbonate and potassium silicate proved to be more effective in reducing the attack of apple scab and powdery mildew on leaves and fruit. Results were obtained for two years with favourable conditions of apple scab and powdery mildew development, when untreated variants exhibited an attack degree at a mean value of 49.77% for scab and 52.13% for powdery mildew. Potassium bicarbonate and potassium bicarbonate mixed with potassium silicate assured the best results in the case of the ‘Idared’, ‘Jonathan’, ‘Jonica’ cultivars regarding apple scab, and ‘Golden Delicious’, ‘Starkrimson’ and ‘Granny Smith’, regarding powdery mildew, where the mean value attack degree was reduced by about three times. The treatments with the products used in the experiments did not register symptoms of phytotoxicity on leaves or flowers. Given that this product is not toxic to human health, it becomes a perspective fungicide, especially for organic fruit tree growing in order to control apple scab and powdery mildew attack.