First report of oat crown rust caused by Puccinia coronata var. avenae f.sp. avenae in South Korea

Oats ( Avena sativa L. cv. Joyang), cultivated during June 2023 in experimental fields of Naju County, South Korea, exhibited crown rust symptoms resembling those caused by isolates of Puccinia coronata . Yellow urediniospores measuring 15.3 ± 3.2 × 13.6 ± 3.0 μm were identified through microscopic examination. Multilocus sequence typing of housekeeping genes in the DNA of this fungal isolate showed identity with P. coronata var. avenae f.sp. avenae , a pathogen of oats in South Korea previously lacking in taxonomic classification. This finding raises concerns of escalated crown rust disease in South Korea due to enhanced temperatures and humidity from climate shifts. Addressing these emerging concerns may require proactive strategies to protect oat cultivation in South Korea.