TOLERÂNCIA DE TIFTON 85 E JIGGS (Cynodon dactylon L.) A HERBICIDAS APLICADOS EM PÓS EMERGÊNCIA

Abstract

Chemical control is an important strategy for weed management in the areas of Tifton 85 and Jiggs (Cynodon dactylon L.). The objective of this work was to evaluate the tolerance of Tifton 85 and Jiggs to different herbicides applied in post emergence of forages. The experiment was conducted in a greenhouse, in IF Goiano Campus of Urutaí, where the plants of Tifton 85 and Jiggs were cultivated in polyethylene pots with capacity of 12 L, until the total development with 40 cm of height, when applied the treatments. Was conducted two experiments in design completely randomized with the forages Tifton 85 and Jiggs and twelve treatments commons: 2,4-D 1,209 g i.a. ha-1, Diurom 2,000 g i.a. ha-1 , Atrazine 2,000 g i.a. ha1, Fluazifope-p-butyl 156,25 g i.a. ha-1, Glyphosate 1080 g i.a. ha-1, Nicosulfuron 62,5 g i.a. ha-1, Imazethapyr 100 g i.a. ha-1, Cletodim 101.6 g i.a. ha-1, Haloxyfop-p-methyl 60.8 g i.a. ha1, Lactofem 144 g i.a. ha-1, Tembotrione 84 g i.a. ha-1 and one control without application, with four replicates, each experimental unit represented by a plant’s pot. The application was with a CO2 pressurized sprayer, with a constant pressure of 2.4 kgf cm-2, equipped with four falt jet Magno ADIA 110.015 bar, spaced 0.5 m, with a volume of water equivalent to 200 L ha-1 . As evaluation of the phytotoxicity of the herbicides were performed at 7, 14, 21, 28, 35, and 50 days after aplication (DAA), through the scale of intoxication of Tifton 85 and Jiggs from 0 to 100, where 0 is the absence of intoxication and 100 the complete death of plants and chlorophyll a and b contents of Tifton 85, using an electronic chlorophyll content meter, in three expanded leaves pre-defined by experimental unit. At the last visual evaluation (50 DAA) as plants were cut at the ground level and the dry matter of the regrowth was evaluated 60 days after the cut (DAC). From the 14 DAA the herbicide glyphosate, following fluazifopp-butyl, presented high phytotoxicity to the attacking grasses and decreased the chlorophyll content of Tifton 85 plants, reducing its development and productivity. As Tifton 85 and Jiggs plants treated with glyphosate did not show regrowth at 60 DAC. The herbicide tembotrione had no influence on the regrowth of Tifton 85 and the herbicides 2,4-D, Atrazine, Cletodim and Lactofem had no negative effect on a regrowth of Jiggs at 60 DAC, being good strategies without chemical weed management in pastures of Tifton 85 and Jiggs, respectively.