Influence of Fungicides on the Tomato and Growth of Botrytis cinerea Pers

Abstract

SPRAYS of maneb (manganese ethylene bisdithiocarbamate) or zineb (zinc ethylene bisdithiocarbamate) increased the incidence¹ of grey mould of tomatoes, caused by Botrytis cinerea Pers., but adding thiram (tetramethylthiuram disulphide) or ‘Dyrene’ (2,4-dichloro-6-o-chloroanilino-s-triazine) to either of the above sprays prevented infection². Apparently maneb and zineb either stimulate the growth of B. cinerea or induce a change in the tomato favouring growth of the fungus. To investigate this phenomenon the effect of these fungicides and other chemicals on the germination and growth of B. cinerea was examined, and tests were made for total-ninhydrin-staining compounds and carbohydrates in exudates washed from the surface of treated tomato leaves and fruit.