The effect of cultivar and fungicide application on the yield and quality of late-seeded forage oats used for swath grazing

The productivity and disease tolerance of annual forages may have large effects on the performance of beef cattle in a swath-grazing system. This study was conducted to evaluate the effects of crown rust (Puccinia coronata Corda f. sp. avenae Eriks.) on the forage yield performance of 2 oat (Avena sativa L.) cultivars (HiFi and CDC Baler) with or without fungicide application in a swathgrazing system. The cultivar HiFi has good resistance to crown rust, whereas CDC Baler is susceptible to crown rust. Unfortunately, barley yellow dwarf virus (BYDV) infected both cultivars and may have influenced the results of the current study. Forage DM yield, regrowth, and forage residue yield samples were collected from each treatment. The nutritional quality of the samples was also analyzed. Mixed-model ANOVA was used in the statistical analysis of forage yield and nutritional performance. The cultivar effect was significant (P < 0.01) for DM yield, regrowth, residue yield, and nutrient quality. The application of fungicide had no influence (P > 0.61) on the DM yield, regrowth, and residue yield of the cultivars. There was no interaction effect (P > 0.16) between cultivar and fungicide application for all yield performances. The results from this study suggest that using a resistant cultivar (HiFi) resulted in greater (P < 0.01) forage DM yield and gross margins. The application of fungicide on HiFi was not economical because of the cultivar's resistance to crown rust. The HiFi cultivar also showed moderate resistance to BYDV. Although agronomic traits need to be considered in selecting cultivars for swath grazing, it is also important for producers to select cultivars with good disease packages that are environmentally suited to the production area. Because of its susceptibility to BYDV, CDC Baler may not be suitable for swath grazing in areas with severe BYDV infestation.