Host Status of Commonly Grown Ornamental Flowers to Root-Knot Nematodes and Efficacy of Biopesticides for Their Management
Abstract
Root-knot nematodes (Meloidogyne spp.), particularly M. incognita, pose a serious constraint to ornamental flower production worldwide, including Pakistan. The present study assessed the host status of eight commonly cultivated ornamental flower species (Petunia hybrida, Viola tricolor, Matthiola incana, Salvia splendens, Tropaeolum majus, Gazania rigens, Calendula officinalis and Dahlia pinnata) against M. incognita. The efficacy of three products (Faline, Axiom and Vampire) was evaluated for their effects on egg hatching, juvenile mortality and nematode management on C. officinalis under greenhouse conditions. Significant variation (P ≤ 0.05) was observed among ornamental species. Nasturtium, Calendula and Pansy were highly susceptible, recording high juvenile populations (17,425, 17,262 and 16,020 J2, respectively), gall formation (338, 234 and 218 galls per root system), egg masses (194, 192 and 178) and female counts (283-315 per root system). In contrast, Stock and Salvia exhibited strong resistance, with minimal J2 populations (283-330), galling (3) and egg mass production (3-4). Petunia, Dahlia and Gazania showed moderate susceptibility. In laboratory assays, biopesticides applied at 1.0% concentration significantly suppressed egg hatching, with Faline reducing hatching to 1.6, 3.0 and 8.0 eggs at 24, 48 and 72 hours, respectively, compared with 28-47.4 in the control. Juvenile mortality was highest with Faline at 1.0%, reaching 43.2% after 72 hours. Protective application of biopesticides on C. officinalis markedly improved plant growth, with Faline-treated plants exhibiting maximum shoot length (25.07 cm), leaf number (21) and shoot weight (6.6 g), while significantly reducing nematode reproduction, including galls (4), females (8), egg masses (9) and J2 populations in roots and soil. These results demonstrate that resistant ornamental species and biopesticides, particularly Faline, offer effective and environmentally safe alternatives to chemical nematicides for managing M. incognita in ornamental production systems.