Skip to main content
APS Plant Health 2025 Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
ViewAttendees 2

TECHNICAL SESSION: Oomycetes

Host Resistance Screening of Baby Leaf Salad Greens Against Downy Mildew Isolates Across the Central Coast of California

Monday, August 4, 2025
10:15 AM - 10:30 AM HST
Location: Ballroom B/C
Abstract Text: Downy mildew is a major threat to baby leaf salad green production in California. Baby kale, a key ingredient in these salad mixes, holds significant economic value, with the crop exceeding $12 million in 2022. Among the different baby kale species, Brassica oleracea is the most widely cultivated. The disease, caused by Hyaloperonospora brassicae, leads to chlorosis, necrosis, and sporulation, making leaves unmarketable. Developing resistant varieties can offer a sustainable solution to disease management by reducing reliance on pesticides. This study evaluated the resistance of baby kale accessions to downy mildew isolates collected across California. Plants were inoculated with an H. brassicae sporangia suspension and incubated under high humidity. Disease severity was assessed on a scale of 0 to 100% based on the presence of chlorotic and necrotic symptoms, as well as sporulation. A total of 212 baby kale accessions were screened, including 190 B. oleracea, 5 B. napus, and 17 B. oleracea x B. napus. These accessions were tested against eight H. brassicae isolates collected from various locations along the Central Coast of California. The final selection included 5 B. oleracea, 5 B. napus, 15 B. oleracea x B. napus accessions, which exhibited disease severity ranging from 0.003% to 0.072%. These findings suggested that breeding resistant baby kale varieties could be a promising strategy for managing downy mildew and highlighted the importance of interspecific breeding in advancing disease-resistance breeding programs.