Influência da época de aplicação de nematicidas em soqueiras sobre as populações de nematóides e a produtividade da cana-de-açúcar

Abstract

RESUMOCom a finalidade de definir a melhor época para aplicação de nematicidas em soqueiras, desenvolveram-se seis experimentos, em canaviais colhidos entre julho e novembro, fazendo aplicação de nematicidas aos 5, 20, 40 ou 60 dias depois da colheita. A aplicação de nematicidas contribuiu para incrementos significativos de produtividade em cinco dos seis experimentos instalados. No experimento em que não se observou incremento significativo de produtividade, as populações de nematóides na área estavam baixas. Nos três tratamentos nematicidas estudados (aldicarb 150G a 8 kg ha -1 ou a 10 kg ha -1 e carbofuran 100G 21 kg ha -1 ) observou-se desempenho semelhante quanto à redução populacional de nematóides e incrementos de produtividade. Para os experimentos colhidos na época seca, observaram-se os maiores incrementos quando os nematicidas foram aplicados aos 40 ou 60 dias depois do corte. Para o experimento colhido na época chuvosa, os maiores incrementos foram verificados em aplicações feitas aos 20 ou 60 dias depois do corte. Pelos resultados, sugere-se que o período após colheita que se deve aguardar para aplicar o nematicida, a fim de obter os melhores incrementos de produtividade, varia em função da época de colheita do canavial, sendo maior (40 a 60 dias) em canaviais colhidos em época seca e menor (20 dias) em canaviais colhidos na época chuvosa.Palavras-chave: cana-de-açúcar, soqueira, nematóides, controle químico. ABSTRACT APLLICATION PERIOD EFFECT OF NEMATICIDES IN SUGARCANE RATOON ON NEMATODES POPULATIONS AND SUGARCANE YIELDThe objective of this work was to define the best period of nematicides application in sugarcane ratoon, Six experiments were carried out in the sugarcane field harvested from July through November during which nematicides were applied at 5, 20, 40 or 60 days after harvesting. Nematicides contributed to increase yield in five of the six experiments. In the experiment in which yield increase was not observed, nematode population was low. The three nematicide treatments (aldicarb 150G at doses 8 kg.ha -1 or 10 kg.ha -1 and carbofuran 100G 21 kg.ha -1) promoted similar reductions in the nematode populations and yield increases. In the experiments harvested during the dry season, higher productions were obtained when nematicides were applied at 40 or 60 days after the harvest and, in the experiment harvest at raining season, the highest production was obtained when the nematicides were applied at 20 or 60 days after harvesting. These results suggest that the period following harvest that must be waited before applying nematicidas in sugarcane rations, in order to obtain the best yield increase, varies with the sugarcane harvest time; being best from 40 to 60 days after harvesting in the dry season and 20 days at raining season.

REACTION OF SUGARCANE GENOTYPES TO PARASITISM OF Meloidogyne javanica AND Pratylenchus zeae

“…This species has been reported as one of the most frequent in Brazilian sugarcane crops (DINARDO-MIRANDA et al, 2003;SEVERINO et al, 2008;BELLÉ et al, 2014). Thus, studies on this pathogen may contribute to minimize losses in crops due to its attack.…”

“…The susceptibility of the varieties evaluated to M. javanica and P. zeae is an important indicator of the need to adopt different control measures, since these species are widely distributed in sugarcane areas. Several management strategies are used to increase the yield of sugarcane crops (DINARDO-MIRANDA et al, 2008;CHAVES et al, 2009b;NOVARETTI;REIS, 2009), however, none have been fully effective in maintaining nematodes populations at levels below the economic damage threshold.…”

“…and root lesion (Pratylenchus spp.) nematodes are the most common pests related to damage in Brazil ( DINARDO-MIRANDA et al, 2008;SEVERINO et al, 2010;BELLÉ et al, 2014). According to Severino et al (2008) Meloidogyne javanica and M. incognita are the most common nematodes associated to sugarcane in Paraná state.…”

“…The importance of root-knot nematodes in sugarcane crops can be noticed by their yield decrease due to the difficulties to control these pathogens (BARROS et al, 2005;DINARDO-MIRANDA et al, 2008). Several methods of control of nematodes have been studied, aiming to decrease phytonematode populations in sugarcane crops to levels below the economic damage threshold.…”

Reproduction of Pratylenchus zeae on Weeds

“…The greatest economic losses caused by P. zeae are reported for sugarcane and corn crops in various regions in the world and Brazil (Blair and Stirling, 2007;Santana et al, 2012). Croplands infested with this pathogen can become infeasible for the cultivation of new crops of these species as well as other cultures equally susceptible to these parasites, making the economic use of the lands unsustainable (Dinardo-Miranda et al, 2008). In studies conducted in sugarcane crops in the northwestern region Rio Grande do Sul, nematodes of the genus Pratylenchus were present in 100% of the samples, and the species P. zeae was found in more than 90% of the samples tested (Bellé et al, 2014).…”