Impact of some stimulants on boosting strawberry plants’ resistance to Tetranychus urticae Koch (Actinidida: Tetranychidae)

The present study was conducted during the two seasons, 2017/2018 and 2018/2019 to evaluate the effect of some stimulating compounds on the mean population number of the movable stages of the two-spotted spider mite Tetranychus urticae per leaflet in two strawberry cultivars, Fortona and Festival. The six tested compounds included fulvic acid 10%, humic acid 15%, salicylic acid 99%, potassium silicates 45%, potassium citrate 55%, and calcium carbonate 95%, with a control untreated group for comparison. The control group had the highest number of T. urticae across all weeks. Treatments with fulvic acid, humic acid, salicylic acid, potassium citrate, potassium silicates, and calcium carbonate showed significantly lower mite counts compared to the control, especially in the later weeks. However, calcium carbonate and potassium silicates were the most effective in reducing T. urticae populations in both strawberry cultivars. Salicylic acid significantly increased trichome density, which may contribute to enhance a kind of resistance against pests. These results suggest that certain stimulating compounds can effectively boost strawberry plants’ resistance to T. urticae by reducing mite populations and increasing a control mechanism such as trichome density.