Agressividade comparada de Pratylenchus brachyurus com P. zeae e eficácia de métodos de controle de nematoides em cana-de-açúcar

Abstract

Pratylenchus zeae, Meloidogyne javanica e M. incognita são nematoides-chave na cana-de-açúcar, no Brasil, mas P. brachyurus também é frequentemente encontrado. Três experimentos foram conduzidos para o estudo. No primeiro, comparou-se a agressividade de P. brachyurus e P. zeae a cultura. No segundo e no terceiro, buscaram-se alternativas de controle. O primeiro e o segundo experimentos foram em vasos de 100 L, a céu aberto e o terceiro em soqueira de quarto a quinto cortes. No primeiro foram inoculados 10, 100, 1.000, 10.000 e 100.000 espécimes/planta, isoladamente. No segundo foram testados Agrolmin® (ácidos húmicos e fúlvicos extraídos de turfa), Agrolmin + Fungos nematófagos (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofurano e Testemunha sem e com nematoides. No terceiro, testaram-se: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0,5 L.m linear-1)], FN (1 L.m linear-1), Formulação de FN (FFN) no Agrolmin Nitro (300 L.ha-1), FFN no Agrolmin Nitro (600 L.ha-1), Carbofurano (6 L.ha-1) e a Testemunha. Nos três experimentos foi avaliada a dinâmica da população das pragas e avaliações biométricas e quantitativas das plantas, ao final. Observou-se que a variedade CTC2 é suscetível à P. zeae e intolerante à P. brachyurus, que foi mais agressivo. Os FN incrementaram a produtividade, principalmente quando associados ao Agrolmin. O parasitismo de H. dihystera reduziu o de M. javanica, mas causou danos à cultura. A FFN no Agrolmin Nitro (300 L.ha-1) reduziu as populações de P. zeae e de M. javanica e elevou a produtividade em 14,6 Mg.ha-1, em relação a testemunha

Pratylenchus zeae, Meloidogyne javanica and M. incognita are the key nematodes in sugar cane in Brazil, but P. brachyurus is also frequently found. Three experiments were conducted. In the first one, the aggressiveness of P. brachyurus and P. zeae to the crop was compared. In the second and third ones alternatives for the control were sought. The first and second experiments were carried out in 100 L pots, in open area and, the third experiment in ratoon of fourth to fifth cropping. In the first one levels of 10, 100, 1,000, 10,000 and 100,000 specimens/plant were inoculated, individually. In the second one it was tested Agrolmin ® (humic and fulvic acids extracted from peat), Agrolmin plus nematophagous fungi (FN), Pochonia chlamydosporia, FN, Helicotylenchus dihystera, Carbofuran and the Control with and without nematodes. In the third experiment were tested: Agrolmin 10:0:10 [Agrolmin Nitro (300 L.ha-1)], Agrolmin Nitro (600 L.ha-1), FN (0.5 L.m linear -1)], FN (1 L.m linear-1) Formulation of FN (FFN) in Agrolmin Nitro (300 L.ha-1), FFN in Agrolmin Nitro (600 L.ha-1), Carbofuran (6 L.ha-1) and Control. In the three experiments it was analyzed the population dynamics of the nematodes as well biometric and quantitative assessments of the plants at the end. It was observed that the variety CTC2 is susceptible to P. zeae and intolerant to P. brachyurus which was more aggressive. The FN increased productivity, especially when associated with Agrolmin. The parasitism of H. dihystera reduced M. javanica population, but caused damage to the crop. The FFN in Agrolmin Nitro (300 L.ha-1) reduced populations of P. zeae and M. javanica and increased productivity by 14.6 Mg.ha-1, compared to control