Evaluation of Verticillium Wilt Resistance in Mentha arvensis and M. longifolia Genotypes.

Verticillium wilt, caused by Verticillium dahliae, is a major constraint to mint (Mentha spp.) production in the United States, and the use of resistant cultivars is an important component of Verticillium wilt management. Two Mentha arvensis and four M. longifolia genotypes were evaluated for resistance to Verticillium wilt in the greenhouse using V. dahliae isolates obtained from different hosts and belonging to different vegetative compatibility groups. Isolates of V. dahliae obtained from peppermint (M. × piperita) caused significantly higher disease severity, plant mortality, and yield reduction than isolates obtained from other hosts. Disease severity, plant mortality, and pathogen incidence in aboveground stems were higher and yields lower in peppermint, the susceptible standard, compared with the resistant standard, native spearmint (M. spicata). Root-dip inoculations of M. arvensis and M. longifolia with isolates of V. dahliae obtained from peppermint produced severe symptoms; however, both species displayed the ability to recover from infection and produce asymptomatic growth from rhizomes. Both M. arvensis cultivars exhibited lower mean disease severity ratings following cutback and regrowth and were not significantly different than native spearmint. The restriction of pathogen movement in aboveground tissue and ability to recover from infection may be important components of V. dahliae resistance in perennial mint cropping systems.