Pathogenicity of Meloidogyne incognita and Pratylenchus zeae, and Their Association with Pythium graminicola on Roots of Sugarcane in Puerto Rico

Abstract

Both Meloidogyne incognita and Pratylenchus zeae, acting separately, reduced significantly the height of the primary shoots, fresh and dry weight of shoots and leaves, and fresh weight of roots of sugarcane cultivar PR 980. The combined action of both nematode species also caused a significant reduction of the height of the primary shoots, weight of shoots and dry weight of leaves, but the reduction was less than that produced in plants inoculated with only one species alone. Also, when both species of nematodes were present simultaneously, the number of internodes was significantly reduced, as compared to the control, but there was no difference in the reduction caused by both species when they were applied together or each one alone. Pythium graminicola reduced significantly the height of primary shoots. The combination of each nematode species with the fungus produced a highly significant reduction of the height of the primary shoots. The reduction was lower than that produced by each nematode species acting separately, but higher than that induced by the fungus alone. No significant reduction was caused by the three microorganisms acting in combination. The data suggested a possible acute antagonism among the two nematode species and the fungus. It also indicated that M. incognita, P. zeae and P. graminicola are pathogenic to sugarcane.