Reação de cultivares de aveia à fusarium graminearum

Abstract

In grain oats, panicle fusariosis is a difficult disease to control, in addition to causing reduction in hectoliter weight, thousand-grain weight and productivity. The use of fungicides is the main strategy to control the disease. This study aimed to evaluate and quantify the control of Fusarium graminearum and the damage caused by fusariosis in grain oat panicles, when using combined chemical and biological fungicides in different application programs, and the effect of integrating these measures on crop yield. Two grain oat cultivars were used: URS Olada (early cycle), and URS Poente (late cycle). The experiment was conducted in a randomized block design with 4 replicates and 5 treatments for URS Olada; and 3 replicates and 5 treatments for URS Poente. The fungicides used were applied sequentially from flowering onwards and are specific for panicle fusariosis, as follows: control (T1), without fungicide application; T2) pidiflumetofen (200 g L-1) + azoxystrobin + cyproconazole (200 g L-1 + 80 g L-1); T3) pidiflumetofen (200 g L-1) + Bacillus subtilis + Bacillus velezensis + Bacillus pumilus (0.5 L-1); T4) bixafem + prothioconazole + trifloxystrobin (125 g L-1 + 175 g L-1 + 150 g L-1) + methyl thiophanate (850 g kg-1); T5) bixafem + prothioconazole + trifloxystrobin (125 g L-1 + 175 g L-1 + 150 g L-1) + Bacillus subtilis + Bacillus velezensis + Bacillus pumilus (0.5 L-1). The following were evaluated: incidence and severity (%) of panicle fusariosis in soft grains; hectoliter weight; thousand grain weight; productivity; germination and seed sanity. T5 had the highest productivity (1693.6 kg ha-1), hectoliter weight (41.7 kg hL-1) and thousand grain weight (29.3 g) for URS Olada; on the other hand, in cv. URS Poente, the best results were obtained in T4 (highest productivity, 1,175.3 kg ha-1) and T3 (highest thousand grain weight, 26.4 g). Furthermore, T2 stood out for promoting the highest seed germination in URS Olada (96%); and T2 (76.5%) and T4 (77.0%) in URS Poente. T4 provided greater control of the disease in soft grains for both cultivars (average of 27.55% disease index). For URS Olada, in T2 and T4 there was a reduction in the incidence of fungi in seeds (Phoma spp., Fusarium spp. and Drechslera spp.); however, in URS Poente, treatments T2 and T3 indicated a greater reduction of Fusarium spp., Phoma spp., and Cladosporium spp. The response of URS Poente was lower than that of URS Olada, indicating that late grain oat cultivars require more rigorous management strategies to mitigate the effects of panicle fusariosis.