By Emmanuel Byamukama
Stem rust of oats was found in one oats cultivar in the Crop Performance Test plots at the SDSU Southeast Research Farm in Beresford (Figure 1). The level of stem rust severity was moderate. Stem rust on oats is usually not a major problem partly due to good resistance in most oat cultivars. Although stem rust can also infect wheat, the type that infects wheat (Puccinia graminis f. sp. tritici) is different from the type that infects oats (Puccinia graminis f. sp. avenae). So far, no stem rust has been found in surveyed wheat fields.
Figure 1. (Left) Stem rust on oats. (Right) A close-up of stem rust pustules on oats
Crown Rust
Severe crown rust was observed on oats in several fields scouted east river in Brookings, Minnehaha, Union, and Douglas counties. West river fields scouted in Tripp, Lyman, and Gregory had low to moderate levels of crown rust. Unlike stem rust, crown rust survives in South Dakota on an alternate host, buckthorn. Because of this, new races of crown rust can develop often and defeat deployed resistance genes in oats (Figure 2). Producers should keep records of cultivars planted and switch between cultivars for the latest resistance genes. View SDSU Extension's oats variety trial results for more information. Fungicides are effective against crown rust when timed at flag leaf/heading especially for oats raised for grain.
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