Foliar application of potassium silicate, acibenzolar-S-methyl and fungicides on the reduction of Pestalotia leaf spot on strawberry

Abstract

Pestalotia leaf spot, caused by Pestalotia longisetula, has become an important disease on strawberry, and fungicide application is the main recommended control strategy. This study evaluated the effect of foliar application of potassium silicate (PS) at the concentrations of 8 and 30 g/L, acibenzolar-S-methyl (ASM), fungicides azoxystrobin (AZO), and mancozeb (MAN) on the reduction of disease severity. Plants were inoculated at 1, 6, and 12 days after application (d.a.a.) of the products. At the 1st d.a.a., there was no difference in disease severity between PS, at the two concentrations, ASM and the control. AZO and the MAN reduced disease severity by 56.3 and 43.8%, respectively, in comparison to the control. At the 6th d.a.a., there was no difference between PS (8 g/L) and the control. PS (30 g/L) reduced disease severity by 61% compared to the control. At the 12th d.a.a., there was no difference between the treatments PS, at the two concentrations, ASM, AZO, and MAN, but these treatments differed from the control. Disease severity was different for the three inoculation times for PS (8 g/L), with the lowest value occurring at the 12th d.a.a. For treatments PS (30 g/L), ASM, AZO, and MAN, disease severity was reduced from the 1st to the 6th d.a.a., but there was no difference between the 6th and the 12th d.a.a. There was no difference between the three inoculation times for the control. Foliar application of PS was as efficient as ASM in reducing the symptoms of Pestalotia leaf spot, especially if sprayed before pathogen inoculation.