Roses are among the most important ornamental crops globally. Major fungal diseases affecting this crop in East-Central Texas are Cercospora leaf spot (Rosisphaerella rosicola Pass.) and black spot (Diplocarpon rosae F.A. Wolf). This study aims to uncover the genetic basis of resistance to these diseases using three biparental F1 autotetraploid rose populations derived from the following crosses: ‘Miracle on the Hudson’ × ‘Morden Blush’ (MoHxMB, N=196), ‘Miracle on the Hudson’ × ‘Morden Fireglow’ (MoHxMF, N=180), and ‘Morden Blush’ × ‘Brite Eyes’ (MBxBE, N=182). The populations, planted in a randomized complete block design with two replications, were scored for disease severity monthly from May to November over two years (2023 and 2024) at the Texas A
