Use of fungicides against powdery mildew during an artificial scab inoculation test in an apple breeding programme...

Our project aimed to develop an effective selection methodology for partial disease resistance. One of its objectives was to define the optimal selection threshold for discarding individual seedlings after artificial scab inoculation tests. Working with large populations of seedlings, it was necessary to conduct the scab tests at intervals throughout the season, with the risk of powdery mildew infection of the young plantlets during the summer. Because Podosphaera leucotricha symptoms prevent breeders from properly evaluating scab symptoms, a trial was conducted to assess the effect of specific anti-mildew fungicides on the results of the scab inoculation test. The results allowed the active ingredient and the optimum time for application in relation to the inoculation date to be determined.