Resistance of oat cultivars to reduction in fungicide use and a longer interval from application to harvest to promote food security
The resistance of oat cultivars to fungicide use reduction and supporting longer harvest application interval can reduce or avoid the risk of food contamination and environmental pollution. We compared oat cultivars for resistance to reduction in the number of fungicide applications and with longer intervals from application to harvest, considering favorable and unfavorable crop year conditions and how they affect yield and progress of major leaf diseases. The study was conducted in 2015, 2016 and 2017, in Augusto Pestana, RS, Brazil. The experimental design was a complete randomized block with three replications in a 22 x 4 factorial scheme for 22 oat cultivars recommended for cultivation in Brazil and four conditions of fungicide use: no application; one application 60 days after emergence; two applications at 60 and 75 days after emergence and; three applications at 60, 75 and 90 days after emergence. In the control of leaf diseases, the fungicide FOLICUR® CE was used in 2015 and 2016 and the fungicide PRIMO® in 2017 at dosages of 0.75 and 0.3 liters ha-1, respectively. Most of the oat cultivars had little addtional production with the third application of fungicide at 90 days after emergence. Therefore, we coulold increase the interval between application and harvest with just two applications, at 60 and 75 days after and emergence. FAEM 4 Carlasul, URS Altiva and URS Guria cultivars gave high yields under most fungicide use conditions, allowing a long interval between the last application and grain harvest.