Host status of petunia cultivars to root-knot nematodes

Abstract

The host status of 26 cultivars of petunia (Petunia hybrida) to Meloidogyne mayaguensis and M. incognita race 4 was evaluated under glass-house conditions. The experiment was carried out in a completely randomized design with six replicates. A tomato cultivar was included as a susceptible host to both nematode species. The inoculum consisted of 3,000 eggs and/or second-stage juveniles of M. mayaguensis or M. incognita per plant. Sixty-four days after inoculation, the plants were harvested and the numbers of galls and egg masses per root system were recorded. All petunia cultivars were highly susceptible to both nematodes and no differences were observed between the two nematode species (P ≤ 0.05). However, fewer galls were formed by both nematodes on cv. Supertunia Lemon Plume and by M. incognita on cv. Supertunia Lavender Pink, and fewer egg masses were formed by M. mayaguensis on cv. Supertunia Lavender Pink and by M. incognita on cv. Supertunia Lemon Plume. The size of the galls induced by M. mayaguensis was unusually larger than that of galls induced by M. incognita (P < 0.05). The largest galls of M. mayaguensis were observed on Easy Wave Red and Sweet Sunshine 5, whereas the largest galls of M. incognita were found on Easy Wave White, Sweet Sunshine 5 and Mini Blue. The gall sizes of both nematodes were significantly larger on tomato than on petunia cultivars (P ≤ 0.05).