Sulfentrazone no controle de plantas daninhas na fase inicial da cultura do eucalipto

Abstract

The chemical method is widely used to control weeds in eucalyptus plantations, especially in the first year of cultivation. The present work had the following objectives: to evaluate the behavior of the tip spectra of TTI 110025, used in herbicide applications in eucalyptus plantations, exposed to different operational pressures, composing the first chapter; To evaluate the sensitivity of the clone (Eucalyptus grandis x E. urophylla) to sulfentrazone and its developmental reflexes, described in the second chapter; To determine the spray volume and dose of the herbicide sulfentrazone suitable for the control of weeds in the eucalyptus crop, composing the third chapter. In the first chapter, a completely randomized design was used, represented by pressures 200, 300, 400, 500 and 600 kPa, with four replications. The technical variables analyzed were Dv0,1, Dv0,5, Dv0,9, relative amplitude (AR), % V < 100 μm and % V > 500 μm. The tip TTI 110025 presented the best results due to the decrease of the variables Dv0,1, Dv0,5, Dv0,9 and % V > 500 μm as the working pressure increased. The low low value of the variable % V <100 μm indicated low drift risk and the high value % V > 500 μm signaled a high potential for runoff in post-emergence applications. In the second and third chapters, a randomized block design of 2 x 5 + 2 factorial arrangement was used: two volumes of syrup (150 and 200 L ha-1 ), five doses of the herbicide sulfentrazone (400, 500, 600 , 700 and 800 g ha-1 ) + treatment with the herbicide flumioxazine (standard) + control without application (control). In the second chapter, the percentage of plant phytotoxicity at 15, 30, 45 and 60 days after application (DAA), stem diameter and height at 90 DAA were evaluated. The clone was sensitive to sulfentrazone at a dose of 800 g ha-1 , which reflected higher necrosis intensity, deformation in new shoots and loss of apical dominance. Syrup volumes 150 and 200 L ha-1 had no stimulant effects on phytotoxicity and plant development. In the third chapter, evaluations of weed control at 45, 60, 75 and 115 DAA and their dry mass (dicotyledonous and xi monocotyledon) values were performed at 60 and 115 DAA. The effect of the sulfentrazone dose control was affected by the reduction of precipitation, reflecting control similarity between doses, with a dose of 800 g ha-1 . The volume of the syrup did not interfere in the control of weeds, it is suggested the use of the smaller volume in the applications. At 115 DAA only the sulfentrazone 800 g ha-1 dose presented a concept of "good" control (71to 80%), other "sufficient" concept doses (61 to 70%).