EFFECTS OF FIVE CONTROL METHODS ON TWO SUGARCANE ECTOPARASITES AND THE FREE LIVING NEMATODES

Abstract

It was studied the effect of five different plant parasitic control methods, ina naturally infested field, on the population dynamics of the two most prevalentsugarcane ecto–parasitic nematodes Helicotylenchus dihystera (the spiralnematode) and Criconemella ornata (the ring nematode) and also on the freelivings considered as a group. The experimental treatments were: 1 –check,sugarcane, var. SP 70 1011, with no treatment, 2 and 3 – respectively,application of the systemic nematicides carbofuran, a liquid carbamate, andterbufos, a granular organophosphate, both at planting, 4 – resting soil, allowingthe growth of the native vegetation; 5 – the alternated planting of velvetbean and Crotalaria juncea, every three mounts, from March to September,and 6 – the inverse sequence of the treatment 5, during the same time andthe same period. For both crops, every three months, the top of the plantswere incorporated into the soil. These two last treatments were followed byfallow, from September to March, the dry season. The obtained resultsindicated that the nematicides had low effect on the two ectoparasiticnematodes and also on the free–living. The resting soil treatment indicatedthe tendency of maintenance of the nematodes in a equilibrium position. Itwas postulated that this treatment when applied in field conditions maybecome a primary source of nematode inoculum for the next sugarcanecrop to came, as far as the two ectoparasitic nematodes are concern. Finally,the two treatments involving the two antagonistic legumes pointed out thatthey can exercise high degree of suppression on H. dihystera population, themost prevalent among all the sugarcane ectoparasitic nematodes in the region.