Efficacy of Heritage (Azoxystrobin), Rootshield WP ( <i>Trichoderma harzianum</i> ), and Subdue Maxx (Mefenoxam) for the Management of Pythium Root Rot in Cabbage Greenhouse Transplants in California, 2025

Pythium root rot, caused by Pythium brassicum, is a disease affecting brassica crops in the United States causing root necrosis, stunting, wilt, and yield loss in both greenhouse and field production. Wilt and damping off are usually observed at the seedling stage while stunting is noticeable in older plants as severity increases over time. This report evaluates the efficacy of a standard synthetic, a biological, and an unregistered synthetic fungicide for the management of Pythium root rot in cabbage (Brassica oleracea ‘Copenhagen Market’) seedlings. Results from these trials aim to improve management of this disease in greenhouse and nursery production.