Silicon on the productivity and on thecontrol of the spittlebug Mahanarva fimbriolata Stål of sugarcane
The advent of automated sugarcane harvesting, and its replacement of traditionalpre-crop burning, has created a favorable environment for the spittlebugMahanarva fimbriolata Stål. The spittlebug was previously considered a problem just inthe sugarcane plantations of northeast Brazil, but it has now become one of the mainproblems for this culture in the South-central region. Silicon has been shown to becapable of inducing resistance of plants to pathogens and insects. The objectives of thiswork were to evaluate the effect of Silicon on the productivity and improvement of thetechnologically measured quality of sugarcane, as well as on the control of thespittlebug in this culture and also to compare the effects of chemical treatment,biological treatment and silicon application on the population of this pest, on the naturalbiological control of this insect by entomopathogenic fungus and on the population ofsome non-target arthropods in this culture. Two experiments were installed andconducted on cultivar SP80-1816 at a commercial sugarcane production area owned byGuaíra Sugar Meal, in Guaíra-SP. The experimental delineation was in randomizedblocks in factorial outline 8x9x5 (eight treatments, nine sampling dates and fiverepetitions) for the populations of spittlebugs, spittlebugs killed by entomopathogenicfungus and some arthropods; and in randomized blocks, with eigth treatments and fiverepetitions, for other variables. The treatments were, Control; 8,2 L ha-1 of potassiumsilicate (one application), 16,4 L ha-1 of potassium silicate (two applications of8,2 L ha-1), 24,6 L ha-1 potassium silicate (three applications of 8,2 L ha-1), 1000 kg ha-1calcium and magnesium silicate, 0,8 kg ha-1 of the insecticide thiamethoxan 250 WG,4,0 kg ha-1 of the biological insecticide Metarhizium anisopliae (sporulated rice) and4,0 kg ha-1 of M. anisopliae (wettable powder). Between November 2005 and February2005 samplings were made of the spittlebugs, spittlebugs killed by entomopathogenicfungus and some arthropods. The analyses of the technological parameters andevaluation of the productivity of the sugarcane were made one year after the installationof the experiments. Increases of 105,40%, 117,59% and 124,50% in the productivity ofthe sugarcane were verified with two and three applications of 8,2 L ha-1 potassiumsilicate and 1000 kg ha-1 of calcium and magnesium silicate, respectively, in one of theexperiments. It was concluded that there was higher sugarcane productivity with theapplication of Si in the area with a lower amount of this element in the soil; there wereincreases in sugarcane productivity with the chemical and biological application ofinsecticides for the control of the spittlebug; the chemical and biological treatments andpotassium silicate in two foliar applications presented the same performance in thecontrol of this insect and the chemical and biological treatments in both formulationsand the application of Si did not affect the natural biological control of the spittlebug bythe entomopathogenic fungus and the population of the arthropods in sugarcane.
Advisor:Marcus Vinicius Sampaio; Suzana Pereira de Melo; Wilson Roberto T. Novaretti; Gaspar Henrique Korndorfer
School:Universidade Federal de Uberlândia
Source Type:Master's Thesis
Keywords:Biological control Chemical
Date of Publication:03/28/2007