Orchard dependent control and prediction of storage scab on apple

Abstract: Scab on apple, caused by Venturia inaequalis, is one of the major fungal diseases in
Belgian fruit production. Over 50 % of the pesticides used in apple cultivation are used for its
control. A reduction of the number of fungicide applications without increasing disease
incidence could be achievable when the amount of the initial scab inoculum of an individual
orchard is known. Therefore, a method was developed to artificially induce ascospore releases
followed by a qPCR assay resulting in a good estimation of the initial scab inoculum in a
specific orchard, prior to the growing season. The same qPCR technique can be used to predict
the development of scab symptoms on fruits during storage. At harvest the amount of scab DNA
can be determined on apple fruits visually free of scab and correlates well with the infestation
degree during storage. In this way, fruit growers are able to estimate, related to storage scab,
the optimal storage time of their fruits. These techniques can result in a better, more orchard
specific scab control strategy and in a higher fruit quality.