Evaluation of disease control provided by the SAR-inducer Benzothiadiazole (Bion) in strawberry.

摘要

Powdery mildew (Podosphaera aphanis) is one of the main diseases of strawberry in greenhouses in Mediterranean climates and is generally controlled by multiple applications of chemical fungicides. The induction of systemic induced resistance (SAR) can serve as an alternative to the use of fungicides. Benzothiadiazole (BTH) is an SAR-inducer that has been shown to provide protection against P. aphanis when applied to leaves. The aim of this study was to determine whether the application of BTH to strawberry roots can activate SAR to the same extent as foliar applications. Trials were performed in a greenhouse and high tunnel under controlled conditions. BTH treatments were applied to the roots, all leaves or only the older leaves of strawberry plants. A water-treated control and a foliar sulphur treatment (standard) were included in the experiments. Treatments were applied before the strawberry leaves were artificially inoculated with P. aphanis conidia. The incidence and severity of powdery mildew infections were assessed following an incubation period. Root applications of different concentrations of BTH (0.1, 1.0 and 10 g L-1) were associated with levels of disease control that were comparable to the control provided by both sulphur treatments and foliar BTH treatments. The application of BTH to older (basal) leaves resulted in the systemic control of the disease. Even though all of the tested BTH concentrations provided acceptable disease control, root applications of BTH (1.0 g L-1) affected plant vigor and root applications of 10 g L-1 BTH were phytotoxic. Root applications of lower rates of BTH can be a valid alternative to foliar applications. This type of application method allows the grower to avoid the problem of residues on fruits of strawberries grown in suspended pots or bags in greenhouses. In addition, using the greenhouse fertigation system to apply these treatments can save time and reduce costs.