Rice cultivars and non-synthetic phytosanitaries screening for rice blast control in Ebro Delta

Abstract Rice blast (Magnaporthe grisea (Herbert) Barr, anamorph Pyricularia grisea Sacc.) represents one of the worst rice diseases. The application of synthetic fungicides is the main method for blast control, yet not allowed for organic rice farming. As an alternative, non-synthetic sulphur and silica-based commercial fungicides might effectively control rice blast in organic farming without contributing to adverse effects on rice growth, yet their efficacy evidence on a broad range of japonica rice cultivars is still scarce. The objective of this study is to screen blast resistance in six temperate japonica rice cultivars while assessing the efficacy of sulphur and silica-based non-synthetic fungicides on them. A two-years field trial was performed following a completely randomized block design arranged in a single factor with 4 replications. The most blast-sensitive cultivar was Bomba, followed by Argila, Guara, J. Sendra and Montsianell, while V.exp.1 was exceptionally blast tolerant. The only effective non-synthetic fungicide for medium blast sensitivity rice cultivars was sulphur at high doses. In contrast, none of the treatments resulted in blast contol improvement in either the most blast-resistant (V.Exp.1) or the most blast-sensitive (Bomba) cultivars. We conclude that sulphur (Thiopron, 82.5% a.i. L− 1, SC, UPL Iberica) at a 7.5 L·ha− 1 dose has potential to help organic farmers control rice blast. Thiopron is registered and commercialized in Spain for rice cultivation.