Induced Systemic Resistance to Cercospora Leaf Spot of Carrot by Inoculation with Cercospora carotae

The possibility of inducing systemic disease resistance in carrot leaves was investigated with the pathogen Cercospora carotae as the agetit for both induction and challenge. The inoculation of plants with C. carotae induced resistance in newly emerged leaves challenged 23 days later. There was an optimum inoculum concentration of 3 x 10"conidia m l ʹ ʹ for inducing resistance, the response decreasing with higher concentrations. Infection of carrot leaves by C. carotae could thus reduce susceptibility to subsequent infections by foliar pathogens later in the growing season. However, the inoculation of leaves with C. carotae did not increase the resistance of roots after harvest when they were wounded and challenged with Botrytis cinerea