ESTIMATION OF DAMAGE TO OKRA (ABELMOSCHUS ESCULENTUS) BY ROOT-KNOT DISEASE INCITED BY MELOIDOGYNE INCOGNITA

Abstract

The pathogenic potential of Meloidogyne incognita on okra (Abelmoschus esculentus) was determined at initial population densities of 0, 1000, 2000 and 4000 second stage juveniles per kg of soil in pots in the glasshouse inoculated after 2nd, 3rd, 4th and 5th week of emergence. Significant reductions in plant height and fresh shoot weight and increases in root weight, number of galls and egg masses were observed at all inoculum densities. With an increase in inoculum level, there was a progressive increase in height and shoot weight reductions, root weight, number of galls and egg masses. Plants inoculated after 2nd week of emergence were heavily damaged. However, with the increase in plant age at the time of inoculation, the damaging effects lowered significantly. Reductions in height and shoot weight and increase in root weight, number of galls and egg masses were found to be directly proportional to inoculum densities. On the other hand, with an increase in the initial inoculum density and plant age there was a corresponding decrease in the reproduction factor being inversely proportional to inoculum densities and plant ages.