First Report of the Early Spore Stages of Sunflower Rust, Caused by <i>Puccinia helianthi</i>, in Nebraska

Fig. 2. Advanced pycnial lesions on cotyledons of sunflower volunteers showing yellowish halo.



Image from Plant Health Progress article:
First Report of the Early Spore Stages of Sunflower Rust, Caused by Puccinia helianthi, in Nebraska