Efficacy of glyphosate applied using an electrostatic sprayer as affected by adjuvant and carrier volumes

B. Campos, Saulo F.; A.R. Cunha, João P.; H.T. Assunção, Heli; C. Alves, Thales; H.S. Zandonadi, César; M.Lemes, Ernane

doi:10.1590/S0100-83582020380100092

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Research Article • Planta daninha 38 • 2020 • https://doi.org/10.1590/S0100-83582020380100092 copy

Efficacy of glyphosate applied using an electrostatic sprayer as affected by adjuvant and carrier volumes

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Background:

The use of electrostatic spray has the potential to optimize pesticide applications; however, further studies are required to verify its effectiveness.

Objective:

The objective of this work was to evaluate the electrostatic application system for the chemical control of weeds with glyphosate and adjuvant in different carrier volumes.

Methods:

The physicochemical properties of the spray solution, charge/mass relations, spray deposition on weeds, losses to the soil, effectiveness of weed control, and spray drift were evaluated. The field experiment was designed to have randomized blocks with four replications in a 2x2x2+2 factorial: the presence or not of electrostatic spray; with and without adjuvant (soybean lecithin + propionic acid); two carrier volumes (50 and 90 L ha^-1); a control without applications and a conventional spray rate (150 L ha^-1) for additional treatments. The study was performed in duplicate.

Results:

The electrostatic system energized the droplets during the application of glyphosate and adjuvant; however, this did not influence the deposition on the weeds, the losses to the soil, and the drift. The adjuvant improved the effectiveness of weed control in various situations, changed the spray solution properties, and reduced the losses due to drift.

Conclusions:

The adjuvant used proved to be an important tool in application technology. The effectiveness of weed control, in general, was not influenced by the electrostatic system.

Keywords:
spray adjuvant; spray drift; spray rate; glyphosate; physicochemical properties

Sociedade Brasileira da Ciência das Plantas Daninhas Departamento de Fitotecnia - DFT, Universidade Federal de Viçosa - UFV, 36570-000 - Viçosa-MG - Brasil, Tel./Fax::(+55 31) 3899-2611 - Viçosa - MG - Brazil
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[1] *Corresponding author: <ernanefito@gmail.com>

Spray solution	pH	Density (g cm^-3)	Viscosity (mPa s^-1)	Surface tension (mN m^-1)	Electrical conductivity (μS cm^-1)	Charge/mass (mC kg^-1)
Gly 50	6.58 C	0.995 D	1.00 BC	36.50 B	18525 A	13.83 B
Gly 50 Adj	5.43 D	1.021 B	1.05 A	30.50 C	17034 B	12.91 C
Gly 90	6.73 B	0.992 E	0.98 C	35.60 B	11242 C	15.33 A
Gly 90 Adj	4.98 E	1.015 C	1.02 B	31.50 C	10151 D	10.66 D
Gly 150	6.65 BC	0.993 E	0.96 D	35.60 B	7312 E	-
Water	6.85 A	1.024 A	0.99 C	71.63 A	16 F	0.00 E
CV (%)	0.85	0.09	1.03	1.19	0.01	0.93
Fc	905*	1,104*	33*	4,261*	8,091.421*	15,468*

Application rate (L ha^-1)	Adjuvant	Deposition (mg g^-1)			Loss to the soil (μg cm^-2)
		Electrostatic		Average	Electrostatic		Average
		With	Without		With	Without
50	With	0.88	1.30	0.98 B	1,785.75	1,873.78	1,722.65
	Without	0.86	0.87		1,716.57	1,514.48
90	With	1.25	1.41	1.46 A	1,579.37	1,571.94	1,693.87
	Without	1.43	1.75 ⁺		2,091.75	1,530.25
150		0.83			1,984.34
CV (%)		36.30			63.45
Fc		F_ExRxA=0.84^ns; F_ExR=0.00^ns; F_ExA=0.17^ns; F_RxA=2.38^ns; F_E=2.16^ns; F_R=9.47*; F_A=0.01^ns; D_unnett=3.18			F_ExRxA=0.03^ns; F_ExR=0.08^ns; F_ExA=0.30^ns; F_RxA=0.34^ns; F_E=0.19^ns; F_R=0.00^ns; F_A=0.00^ns; D_unnett=0.29^ns

Application rate (L ha^-1)	Electrostatic	Deposition (mg g^-1)		Loss to the soil (µg cm^-2)
Application rate (L ha^-1)	Electrostatic	With adjuv.	Without adjuv.	With adjuv.	Without adjuv.
50	With	0.45	0.30	3,104.03 ⁺	2,522.15 ⁺
	Without	0.43	0.33	2,141.24 ⁺	2,686.36 ⁺
	Average	0.44 a	0.32 b	2,622.63	2,604.25
90	With	0.60 ⁺	0.32	2,972.18 ⁺	1,312.37 ⁺
	Without	0.52	0.22	2,079.20 ⁺	2,370.85 ⁺
	Average	0.50 a	0.29 b	2,525.75	1,841.61
150		0.34		6,171.87
CV (%)		30.88		44.99
Fc		F_ExRxA=0.16^ns; F_ExR=1.26^ns; F_ExA=0.06^ns; F_RxA=3.83^ns; F_E=0.96^ns; F_R=0.80^ns; F_A=22.58*; F_Dunnett=0.69^		F_ExRxA=0.29^ns; F_ExR=0.39^ns; F_ExA=4.06^ns; F_RxA=0.76^ns; F_E=0.17^ns; F_R=1.26^ns; F_A=0.84^ns; F_Dunnett=39.25**

Distance	Nylon collector (Vertical)				Paper collector (Horizontal)
	Adjuvant		Electrostatic		Adjuvant		Electrostatic
	With	Without	With	Without	With	Without	With	Without
5 m	21.52 b	23.72 a	22.58	22.67	2.88 b	3.44 a	3.00	3.32
CV (%)	13.03				17.80
Fc	F_ExA=0.02^ns; F_E=0.00^ns; F_A=5.01*				F_ExA=0.16^ns; F_E=3.03^ns; F_A=8.73**
10 m	19.68 b	22.74 a	21.07	21.35	2.57 b	2.87 a	2.71	2.73
CV (%)	12.67				7.99
Fc	F_ExA=0.04^ns; F_E=0.09^ns; F_A=11.62**				F_ExA=0.00^ns; F_E=0.11^ns; F_A=17.05**
15 m	18.96	19.60	18.89	19.67	2.54 b	2.65 a	2.59	2.60
CV (%)	6.56				4.79
Fc	F_ExA=1.40^ns; F_E=3.39^ns; F_A=2.33^ns				F_ExA=0.16^ns; F_E=0.00^ns; F_A=7.30**