Alternativas para o manejo integrado de fitonematóides em cana-de- açúcar em tabuleiros costeiros de Pernambuco

Abstract

In Northeastern Brazil the land use of sandy costal table with sugarcane (Saccharum sp.)cropping associated with high temperatures and long dry seasons have increased plant parasitism nematode, particularly Meloidogyne spp. and Pratylenchus zeae, severity in fields. Despite many control measures have been applied, none has been efficient enough to keep nematode level under economic threshold. Therefore three experiments were conducted searching for more efficient, economic and ecological sound control alternatives. In the first experiment, it was evaluated the effect of neen (Azadirachta indica) oil, filter pressed mud and aldicarb on endoparasitic nematodes density and on technological and productive variables of sugarcane in a naturally infested field. There was no significant difference among treatments within technological variables. Stalk diameter and productivity were lower (P= 0.05) in the control and the nematicide treatment. Plants with filter cake (60 t/ha) and filter cake (60 t/ha) + Neen oil (1%) presented the highest (P=¤0.05) productive means, showing no significant difference in plant height and stalk number. Meloidogyne spp. densities in both soil and root were not affected by treatments, in contrast to P. zeae, which presented the lowest (P=H0.05) density in plots with aldicarb or neen oil (2%), indicating efficiency these products under field conditions. In the second experiment, it was evaluated acibenzolar-S-methyl (ASM), silicated fertilizer, and neen extract efficiency on the integrated management of Meloidogyne spp. and P. zeae in a sugarcane field. The association filter cake (50 t/ha) + aldicarb (20 kg/ha) + neen extract (1%) sprinkled on seed stalks significantly increased plant height. ASM (100g/100 L) sprinkled on seed stalks and aldicarb (20 kg/ha) + ASM (100g/100 L) sprinkled on shoots increased (P=o0.05) stalk diameter. The highest (P= 0.05) increases in productivity occurred in plots with filter pressed mud and silicated fertilizer. There was no significant difference in endoparasites densities in soil, incontrast to the roots, in which Meloidogyne spp. densities were significantly lower in plots with silicated fertilizer alone or in association with the other treatments. ASM did not affect root-knot nematode densities and neen extract was efficient only in association with aldicarb or aldicarb + filter cake. Pratylenchus zeae was not affected by any treatment. In the third experiment it was investigated under greenhouse the effects of three mineral organic complexes (Coda Radimax, Coda Humus PK and Coda Vit) on induction of resistance to M. incognita in three sugarcane varieties (RB 92579, RB 863129, RB 867515). All varieties were good host to M. incognita. Comparing to the untreated control, Coda Radimax significantly decreased final number of eggs per root system in all sugarcane varieties. Coda Humus-PK and Coda Vit were efficient in reducing eggs density in RB 867515 but not in RB 863129. All tested compounds did not affect stalk diameter, number and dry weight of shoots. No significant anatomical changes were observed in the M. incognita inoculated tissues examined using bright field microscopy, compared to corresponding tissues in healthy plants.