Fungi occurred on marigold (Tagetes L.) and harmfulness of Fusarium species to selected cultivars

In Poland, cultivars belonging to three species of Tagetes are grown: T. erecta, T. patula, T. tenuifolia. Presented studies were conducted in 2015 in two localities of the Lublin region. Those studies included cultivars of Tagetes spp.: T. erecta (cv. ‘Alaska’, ‘Hawaii’, ‘Mann Im Mond’), T. patula (cv. ‘Bolero’ and ‘Carmen’) and T. tenuifolia (cv. ‘Lemon Gem’ and ‘Lulu’). Six weeks after the sowing and in flowering stage of analyzed marigold cultivars, the plants healthiness was assessed. The mean values of the disease index ranged from 16.25 to 29.0. The main cause of root infection at the seedling stage proved to be the species of Fusarium and Rhizoctonia solani. Proportion of plants with disease symptoms in flowering stage ranged from 1.25 to 5.5%. Regardless of the place of cultivation, species: A. alternata, F. culmorum and F. equiseti were the most often isolated from diseased plants in the flowering stage. Studies on the susceptibility of analyzed cultivars of marigold to infection by Fusarium culmorum, F. equiseti and F. sporotrichioides were conducted in a growth chamber. Significantly, the lowest value of the disease index of cultivar ‘Bolero’ (T. patula) allows to accept that cultivar as the least susceptible to infestation by Fusarium spp. under conditions of controlled temperature and humidity.