Host Status of Commonly Planted Ornamentals to Meloidogyne incognita and Management through Endophytic Bacteria

Abstract

Meloidogyne incognita is the most dangerous plant parasitic nematode species that infects a huge number of crop plants. It also infects the ornamental plants resulting in a serious growth-limiting factor in ornamentals. In this study, the response of ten ornamental plants to M. incognita was assessed in pot experiments. All the ornamental plant species showed varying degree of infection of M. incognita. Rhapis excels and Ophiopogan japonicas were moderately resistant, Cordyline fruticosa, Hibiscus syriacus and Carrisa macrocarpa were moderately susceptible, Murraya paniculata and Ficus benjamina were susceptible, F. elastica, Artemissia stelleriana and Duranta repens were highly susceptible to M. incognita infection according to a well established 0-4 galling scale. The highest galling index and reproductivity of nematodes, i.e., total number of egg masses, juveniles and females, were observed in highly susceptible plants. The values of canopy length, dry root weight, fresh root weight, root length, dry shoot weight and shoot height was variable for all plants and the maximum canopy length was recorded in C. macrocarpa, while maximum fresh root weight, dry root weight, root length and shoot weight were recorded in O. japonicus and R. escelsa, respectively. The susceptible plants were subjected to the application of endophytic bacteria Pantoea agglomerans strain MN34 and Pseudomonas putida strain MN12 in a pot experiment. Both endophytes significantly decreased the galling index and promoted the growth of the plants root length, shoot weight and canopy length; however, the highest root weight was observed in the control treatment. P. agglomerans showed more reduction in galling index and increase in plant growth than P. putida. The results concluded that M. incognita has a wide host range in ornamental plants and they could be managed by using antagonistic, growth promoting endophytic bacteria.