Planta Daninha (2009) 27, 353-361

S.J.P. Carvalho, V. Damin, A.C.R. Dias, M.S.C. Melo, M. Nicolai and P.J. Christoffoleti (2009)
Dessecação de plantas daninhas com glyphosate em mistura com ureia ou sulfato de amônio
[Weed desiccation with glyphosate mixed with urea or ammonium sulfate]
Planta Daninha 27 (2), 353-361
Abstract: Glyphosate is a non-selective systemic herbicide used to control annual and perennial weeds worldwide. Molecule absorption occurs through the plant's photosynthetically-active tissues; however, some factors might reduce its efficacy, such as morphology and specific diversity, rain after application, water quality and tank mixtures with other chemicals. Thus, this work aimed to evaluate the influence of ammonium sulfate or urea addiction to spray tank on glyphosate efficacy for weed desiccation. Two trials were carried out in Piracicaba - SP, with applications of glyphosate (720 and 1440 g ha^-1) alone or combined with two rates of ammonium sulfate (7.5 and 15.0 g L^-1) or urea (2.5 and 5.0 g L^-1), over the weeds Alternanthera tenella and Sorghum halepense. For the least susceptible species (S. halepense), the addition of nitrogen sources to the lower rate of glyphosate accelerated plant death, increasing the control levels up to 7.3%, at 21 days after application (DAA). However, the effects were not observed when control, fresh and dry mass were evaluated at 28 DAA. Glyphosate recommended rate for each species promoted appropriate control, without the need to add ammonium sulfate or urea.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Portuguese)
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Database assignments for author(s): Pedro Jacob Christoffoleti

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Sorghum halepense (weed)		Brazil (south)
	Alternanthera ficoidea (weed)		Brazil (south)