Effectiveness of herbicides isolated or in mixture in control of the exotic plant invasive Urochloa subquadripara

O objetivo deste estudo foi avaliar a eficácia dos herbicidas glyphosate, saflufenacil, imazamox, imazapyr e penoxsulam, isolados e em mistura, no controle de Urochloa subquadripara. Para tanto, em casa de vegetação, cinco ponteiros das plantas foram transplantados em caixas de 2,5 litros contento 5 cm de solo, areia grossa lavada e composto orgânico (na proporção 1:1:1). Após 30 dias, foi realizada a aplicação dos herbicidas com pulverizador costal à pressão constante de 25 psi mantida por CO2, com consumo de calda equivalentes a 200 L ha-1. As avaliações foram efetuadas por meio de notas de eficácia aos 3, 7, 15, 21, 30, 45 e 60 dias após a aplicação (DAA). Os herbicidas glyphosate e imazamox, isolados, apresentaram excelente controle (100%) de U. subquadripara, enquanto que, o imazapyr e o penoxsulam (48 g ha-1) apresentaram controle satisfatório com 80 a 85% de eficácia de controle. Os herbicidas glyphosate, imazamox e imazapyr (isolados e em mistura), o saflufenacil + glyphosate (mistura) e o penoxsulam + glyphosate (mistura) podem ser empregados em programas de manejo desta planta aquática invasora. The objective of this study was to evaluate the efficacy of glyphosate, saflufenacil, imazamox, imazapyr and penoxsulam alone or in combination in the control of Urochloa subquadripara. To do so, in greenhouse, five plant pointers were transplanted into 2.5 liter boxes containing 5.0 cm of soil, washed coarse sand and organic compound (1:1:1; ratio). After 30 days, the herbicides with costal sprayer were applied at a constant pressure of 25 p.s.i. maintained by CO2, with consumption of syrup equivalent to 200 L ha-1. The evaluations were performed through efficacy notes at 3, 7, 15, 21, 30, 45 and 60 days after application (DAA). The herbicides glyphosate and imazamox, isolated, showed excellent control (100%) of U. subquadripara, whereas imazapyr and penoxsulam (48.0 g ha-1) presented satisfactory control with 80 to 85% control efficacy. The herbicides glyphosate, imazamox and imazapyr (isolated and mixed), saflufenacil + glyphosate (mixture) and penoxsulam + glyphosate (mixture) can be used in management programs of this invasive aquatic plant

<b>Sensitivity of aquatic organisms to ethanol and its potential use as bioindicators

The aim of this research was to evaluate the feasibility for the use of the organisms Lemna minor, Azolla caroliniana, Hyphessobrycon eques, Pomacea canaliculata and Daphnia magna as exposure bioindicators for ethanol (lethal and effective concentration 50% - LC50(I)/EC50(I)). Thus, the following concentrations were used 5.0; 10.0; 20.0; 30.0; 40.0 and 50.0 mg L-1 ethanol on L. minor; 25.0; 50.0; 75.0; 100.0; 150.0 and 200.0 mg L-1 on A. caroliniana; 0.3; 0.5; 1.0; 2.0 and 3.0 mg L-1 on H. eques; 0.05; 0.10; 0.20; 0.40 and 0.80 mg L-1 on P. canaliculata; and 40.0; 60.0; 80.0; 100.0; 120.0 and 140.0 mg L-1 on D. magna. An untreated control was also kept for all organisms, with three repetitions. The increase in the ethanol concentration elevated the electrical conductivity and decreased the water dissolved oxygen and pH. The ethanol LC50 for L. minor and A. caroliniana were 12.78 and 73.11 mg L-1, respectively, and was classified as slightly toxic; 1.22 mg L-1 for H. eques (moderately toxic); 0.39 mg L-1 for P. canaliculata (highly toxic) and 98.85 mg L-1 for D. magna (slightly toxic). Thus, H. eques and P. canaliculata have showed good potential for the use as ethanol exposure bioindicators on water bodies.