Evaluation of Biological and Conventional Fungicides for the Management of Marssonina Leaf Blotch on ‘Rome Beauty’ Apples in NC, 2023

Marssonina leaf blotch (MLB) is a disease of apple caused by the fungal pathogen Marssonina coronaria. On foliage, MLB results in grayish-brown to purple leaf lesions, progressing into chlorosis and defoliation. This report evaluates the efficacy of both conventional and biological fungicides in controlling development of MLB symptoms. The trial was conducted at the Mountain Horticultural Crop Research and Extension Center in Mills River, NC, on 23-year-old Malus × domestica ‘Rome Beauty’ trees. Results from the trial will help advise growers in developing management programs for MLB, as well as provide insight into options for spray programs that utilize reduced loads of conventional fungicides.