The effect of nine fungicides and chitosan on the viability of Phomopsis viticola Sacc. spores occurring abundantly in pycnidia on carnation leaves, was tested in the laboratory conditions. The chemicals selected represent different mode of action on the pathogen and they were recognized as very effective in limiting P. viticola development within many viticultural regions. Fungicides were tested at six various concentrations of active ingredients, i.e. 10, 50, 100, 200, 500 mg. a.i./cm3 and at the concentrations that were recommended by the manufacturers. It was found that chlorothalonil, flusilazol and thiophanate – methyl caused the decay of all P. viticola spores in each studied concentration. After using mancozeb, cyprodinil, azoxystrobin and chitosan a strong inhibition of spore viability were also observed, especially at the concentrations of 100 mg of a.i. on cm3 and above. The other fungicides seem to be less effective compared with the above-metioned ones. Basing on the present studies and abundant information from literature, some of the most effective chemicals which should be tested on grapevine plantations in Poland were indicated.