CO2-pressurized Sprayer Research Articles

Volume de calda e espetro de gotas no controle de Bidens pilosa e Ipomoea triloba com o herbicida Fomesafen

ABSTRACT Among weed control methods, chemical control using herbicides is one of the most widely employed due to its practicality and efficiency. However, there is still a lack of reliable information regarding the effectiveness of low-volume spraying and the droplet spectrum for contact herbicides, such as fomesafen. The objective was to determine the spray volume and droplet spectrum for applying the fomesafen herbicide and its efficacy in controlling hairy beggarticks (Bidens pilosa) and littlebell (Ipomoea triloba). The herbicide was applied using a CO2-pressurized knapsack sprayer with TT11002 spray tip spaced at 0.50 m, operating at pressures of 100 kPa (very coarse droplets) and 400 kPa (medium-sized droplets) with spray volumes of 35, 70, 140, and 280 L ha-1, obtained by varying the application speed. At the time of application, the percentage of covered area and droplet density (droplets cm-²) were evaluated on water-sensitive paper labels using the DropScope® program. The best control results for hairy beggarticks were achieved when the application was performed with very coarse droplets at a pressure of 100 kPa, with a spray volume between 65 and 280 L ha-1, droplet density exceeding 60 droplets cm-2, and coverage greater than 10%. Fomesafen does not provide effective control of littlebell.

Sesame (Sesamum indicum L.) Response to Soil Additives Applied in-Furrow at Planting

Aims: Studies were conducted to study the response of sesame to soil additives applied in-furrow. 
 Study Design: Randomized complete block with 4 replications.
 Place and Duration of Study: Field experiments were carried out during the 2016 through 2018 growing seasons in south-central Texas near Yoakum (29.27704o N, -97.12453o W).
 Methodology: Sesame seed was planted < 2.54 cm deep. Treatments were applied using a CO2-pressurized sprayer in 46.8 L ha-1 of water with one Teejet® orifice disc #45 nozzle per row immediately after seed drop but prior to furrow closure. Each plot consisted of two rows spaced 97 cm apart and 7.6 m long. Sprinkler irrigation was applied on a 2- to 3-wk schedule throughout the growing season as needed. S-metolachlor at 1.4 kg ha-1 was applied preemergence while clethodim at 0.11 kg ha-1 and diuron at 1.12 kg ha-1 were applied postemergence to control annual grasses and broadleaf weeds that were present. 
 Results: In 2016, treatments containing 7% N + 10% chelated Fe, gibberellic acid + 3-indolebutyric acid (0.045%) + cytokinin as Kinetin (0.09%), and pop-up fertilizer (9-30-0 + Zn) resulted in the greatest sesame emergence. In 2017, 2% N, bifenthrin + Bacillus amyloliquefaciens strain D747, and humic acids + Bacillus spp. resulted in greater emergence (90-97%) while in 2018, Azospirillum brasilense and 2% N resulted in the greater emergence (90-91%). In 2016, 2% N produced the greatest yield while in 2018 2% N and the 3-way combination of cytokinin as kinetin (0.090%) + gibberellic acid + indole-3-butyric acid (0.045%) resulted in up to a 117% increase in yield over the untreated. 
 Conclusion: The 3-way combination of gibberellic acid + 3-indolebutyric acid (0.045%) + cytokinin as kinetin (0.090%) and 2 % N proved to be the most consistent soil additives and resulted in a yield increases in the two years that the studies were harvested.

Deposition of diquat with different spray tips, efficiency on common water hyacinth, and effect on water quality

Eichhornia crassipes, known as common water hyacinth, has a high growth rate and produces large amounts of biomass when there are imbalances in water bodies, making it one of the worst aquatic weeds in the world. A study was carried out under small water reservoir field conditions to evaluate the herbicide diquat (960 g ha−1) in controlling this species, at the adult stage development. Four spray tips (AI 11002VS, XR 11002VS and, TXVK-8 with spray volume of 200 L ha−1 and XR 11003VS with 400 L ha−1) were tested. Spraying was performed using a CO2-pressurized sprayer under constant pressure attached to a boat. Plant control was visually evaluated at 1, 3, 7, 11, 14, 21, 29, 60, 87, and 98 days after herbicide application and dry matter accumulation was determined at the end of the experimental period, as well as the spray solution deposition in the application area and water physical and chemical quality. The herbicide diquat was efficient in controlling E. crassipes plants at the dose applied and in development stage of the studied plants, regardless of the type of spray tip at the end of the evaluations. At the beginning of evaluations, the spray tip XR 11002VS was the least effectivity in controlling water hyacinth plants. Spray solution losses were high in all tips tested for control of E. crassipes plants, and the spray tips AI 11002VS and XR 11003VS provided the lowest losses during spraying. No water physical or chemical characteristics were negatively affected by diquat application.

Safflower (Carthamus Tinctorius L.) Response to Drift Rates of Glyphosate

The paper presented the field studies carried out in Ankara during 2017- 2019 to established the safflower responses (Carthamus tinctorius L. var. Remzibey-05) to drift rates of glyphosate. The herbicide at the rate of 18, 9, 4.5 and 1.44 g active ingredient (a.i.) ha-1 was applied at a spray volume of 19.2 L ha-1 to safflower seedlings at 2-4 true leaf stage using a CO2 pressurized knapsack sprayer. Crop injury and yield reduction caused by the herbicide was determined at 28 days after treatment (DAT) and at harvest. As the drift dose of glyphosate increases, the phytotoxicity occurring in the safflower plant also increases and reached to 68.75-73.75% 28 DAT. Yield reduction caused by the lowest drift rate of glyphosate was limited, 13-25%, compared to the nontreated control. At the highest drift dose, the plants could not produce spike and seeds.

Seletividade de sulfentrazone na cultura do girassol

The objective of this study was to evaluate the selectivity of the sulfentrazone molecule in post emergence in the sunflower crop. The experiment was conducted in 2014 at Campo Novo do Parecis. The experimental design was a randomized complete block design with nine treatments and four replications. The treatments consisted of seven rates of sulfentrazone (100, 125, 150, 175, 200, 225 and 250 mL ha-1) and two controls, one with manual weeding and one without weeding. The application of the herbicide was done with CO2 pressurized costal sprayer and equipped with an application bar containing five tips of the Teejet XR 110 02vs model, with application volume of 200 L ha-1. It was evaluated the phytotoxicity (%), chapter height, stem diameter, mass of the chapter, mass of achenes per chapter, mass of the plot and mass of thousand achenes. There was a reduction in the chapter height at rates of 225 and 250 ml p.c ha-1, while in the other variables no significant differences were observed. Up to 14 days after application (DAS), injuries were observed, which disappeared in the assessment performed at 21 DAS. The yield of sunflower crop was not affected by the doses of sulfentrazone. Sulfentrazone doses were selective for sunflower cultivation.

CHEMICAL AND ENERGETIC CHARACTERISTICS OF AFRICAN SWEET SORGHUM AS A SOURCE OF BIOENERGY

ABSTRACT The aim of this study was to evaluate the energetic potential achieved by the application of phyto-regulators to sweet sorghum cultivars. A randomized complete block design was used. Experiments were conducted using two sweet sorghum cultivars (BRS 508 and BRS 509), fourphyto-regulators (ethephon, ethyl-trinexapac, glyphosate, and sulfometuron-methyl), and a control; four replicates were performed 70 days after sowing, at the beginning of the flowering phase of the plants, with the aid of a CO2-pressurized coastal sprayer. The plants were harvested after 40 days, with the stems being cleared at the height of the apical bud, and were subjected to grinding for the extraction of broth. The following analyses were carried out: chemical (total extractives, lignin, and holocellulose contents), proximate (volatile matter, fixed carbon, and ash contents), and energetic (higher heating value). Multiple comparison (Tukey) and linear correlation (Pearson) analyses were carried out at a 5% significance level. The phyto-regulators positively and significantly influenced the chemical attributes and contents of lignin and fixed carbon. It was concluded that glyphosate, sulfometuron-methyl, and ethephon enhanced the biomass/bioenergy potential of sweet sorghum cultivars.

EARLY PRUNING OF EUCALYPTUS PLANTS USING GLUFOSINATE AMMONIUM

ABSTRACT Eucalyptus stands out in the Brazilian silvicultural sector as the most planted tree species for commercial purposes thus, practices that facilitate management and improve wood quality are increasingly required. Although artificial mechanical pruning has been used for this crop, the use of herbicides for pruning can be more practical, rapid and have lower costs. Thus, the objective of this work was to evaluate the use of glufosinate ammonium in the chemical pruning of eucalyptus plants. Eucalyptus seedlings were transplanted into 10-L pots filled with soil and substrate and subjected to the treatments (mechanical pruning, chemical pruning, and no pruning) 90 days after transplanting. Lateral branches were cut with pruning shears for the mechanical pruning. Glufosinate ammonium (500 g a.i. ha-1) was applied to the sides of the plants for the chemical pruning, simulating a field-planting row (3.5 x 2.0 meters), using a CO2-pressurized sprayer; the untreated branches were covered with plastic bags to avoid receiving the herbicide. The percentage of artificial pruning used was 60% of the vertical height of the eucalyptus plants. Glufosinate, glutamate, and ammonia contents, electron transport rate, percentage of pruning, plant height, number of leaves, and dry matter mass of the plants were evaluated. The application of glufosinate ammonium defoliate the treated branches and did not affect significantly the parts of the plants that did not receive the herbicide regarding the evaluated compounds, and growth of the plants, denoting that glufosinate ammonium can be used for chemical pruning of eucalyptus plants.

Cross-spectrum Insect Control with Foliar Insecticides in Broccoli, 2014: Table 1

The objective of this trial was to evaluate the efficacy of insecticide mixtures compared to Exirel applied alone, for cross-spectrum control of major insect pests (sucking and chewing pests) in broccoli under fall growing conditions. Broccoli “Emerald Crown” was direct seeded into double row beds on 42-inch centers on 4 September, 2014. Plots were two beds in width by 45 ft in length and bordered by two untreated beds. Stand establishment was achieved using overhead sprinkler irrigation and irrigated with furrow irrigation thereafter. Four replications of each treatment were arranged in an RCB design. Product formulations and rates for each compound are provided in Table 1. Two foliar sprays were applied on 30 September and 15 October with a CO2 pressurized boom sprayer that delivered a broadcast application through 2 TXVS-18 …

Evaluation of Insecticides for Control of the Sugarcane Aphid in Grain Sorghum, 2014: Table 1

A study was conducted at the LSU AgCenter Dean Lee Research Station in Alexandria, LA, to evaluate insecticides for management of the SA. Six insecticide treatments, in addition to an untreated check, were assessed in an RCB design with four blocks and one replicate per block. Grain sorghum (Dyna-Gro GX13355) was planted on 5 May on 38-inch centers at a density of 83,100 seeds/acre. Plots were four rows wide and 35 ft long. Insecticides were applied on 1 Jul. A CO2-pressurized bicycle sprayer calibrated to deliver 10 gpa at 40 psi was used with a four-row boom equipped with eight TeeJet TX …

Efficacy of Soil-Applied Systemic Insecticides Against Tobacco Pests, 2014

Efficacy of several soil-applied insecticides (Table 1) was tested against key tobacco pests: TFB, TBW, GPA, and tobacco/tomato hornworms (HW). Two identical experiments were conducted at the Upper Coastal Plain Research Station (UCPRS) in Rocky Mount, NC, and the Lower Coastal Plain Research Station (LCPRS) in Kinston, NC. In each experiment, four replicates of the six treatments, including an untreated check, were arranged an RCB design. Each 0.018-acre plot consisted of four, ca. 25 plant, rows. At LCPRS, pre-transplant greenhouse tray drench (GTD) insecticide applications were made on 7 May 2014 in 1 L water using a CO2-pressurized sprayer fitted a single flat-fan nozzle. Twice the application volume was used to wash the material into the root zone immediately following treatment. GTD treatments were applied as above at UCPRS on 28 Apr. The plants were transplanted on 5 May at UCPRS and 8 May at LCPRS, and in-furrow transplant water (TPW) treatments were applied in ca. 160 gal/A of water using four 5-gal mini-tanks affixed to the planter. Plants received no additional insecticide treatments for the …

EVALUATION OF EXIREL AND TORAC FOR CONTROL OF WESTERN FLOWER THRIPS ON ROMAINE LETTUCE, 2013

The objective of the trial was to evaluate the efficacy of two new active ingredients, Exirel and Torac, against western flower thrips relative to the industry standards on romaine lettuce. Romaine ‘Sunbelt’ was direct seeded on 24 Jan, 2013 at the Yuma Valley Agricultural Center, Yuma, AZ into double row beds on 42 inch centers. Stand establishment was achieved using overhead sprinkler irrigation, and irrigated with furrow irrigation thereafter. Plots were two beds wide by 35 ft long and bordered by two untreated beds. Four replications of each treatment were arranged in a RCB design. Formulations and rates for each compound are provided in the tables. Two foliar sprays were applied on 3 and 13 Mar. The applications were made with a CO2 pressurized boom sprayer that delivered a broadcast application at 40 psi and 22.5 gpa through 2 TXVS-18 ConeJet nozzles per bed. An adjuvant Dyne-Amic (Helena Chemical Co.), was applied at 0.25% to all treatments. Numbers of WFT from 5 plants per replicate were recorded at various sample dates following each application (DAT). Relative WFT numbers were measured by removing plants and beating them vigorously against a screened pan (12 inch x 7 inch x 2 inch) for a predetermined time (10 s). A 6 inch by 6 inch sticky card was placed inside of the pan to catch the dislodged WFT. Sticky cards were then taken to the laboratory where adult and larvae were counted. Because of heterogeneity of mean variances, data were transformed using a log10 (x + 1) function before analysis and subjected to ANOVA; means were compared using an F-protected LSD (P ≤ 0.05). Means from non-transformed data are presented in the tables.

EVALUATION OF LANNATE TANK-MIXTURES FOR CONTROL OF WESTERN FLOWER THRIPS ON ROMAINE LETTUCE, 2013

The objective of the trial was to compare the efficacy of Lannate tank-mixtures against WFT on romaine lettuce. Romaine ‘Big Green COS’ was direct seeded on 7 Dec, 2012 at the Yuma Valley Agricultural Center, Yuma, AZ into double row beds on 42 inch centers. Stand establishment was achieved using overhead sprinkler irrigation, and irrigated with furrow irrigation thereafter. Plots were two beds wide by 35 ft long and bordered by two untreated beds. Four replications of each treatment were arranged in a RCB design. Formulations and rates for each compound are provided in the tables. Foliar sprays were applied on 4 and 17 Feb. The applications were made with a CO2 pressurized boom sprayer that delivered a broadcast application at 40 psi and 22.5 gpa through 2 TXVS-18 ConeJet nozzles per bed. An adjuvant Dyne-Amic (Helena Chemical Co.), was applied at 0.25% vol/vol to all treatments. Numbers of WFT from 5 plants per replicate were recorded at various sample dates following each application (DAT). Relative WFT numbers were measured by removing plants and beating them vigorously against a screened pan (12 inch x 7 inch x 2 inch) for a predetermined time (10 s). A 6 inch by 6 inch sticky card was placed inside of the pan to catch the dislodged WFT. Sticky cards were then taken to the laboratory where adult and larvae were counted. Because of heterogeneity of mean variances, data were transformed using a log10 (x + 1) function before analysis and subjected to ANOVA; means were compared using an F-protected LSD (P ≤ 0.05). Means from non-transformed data are presented in the tables.

EFFICACY OF Torac Tank-MIXTURES against WESTERN FLOWER THRIPS ON ROMAINE LETTUCE, 2013

The objective of the trial was to compare the efficacy of Torac tank-mixtures to industry standards for western flower thrips control on romaine lettuce. Romaine ‘Big Green COS’ was direct seeded on 27 Nov, 2012 at the Yuma Valley Agricultural Center, Yuma, AZ into double row beds on 42 inch centers. Stand establishment was achieved using overhead sprinkler irrigation, and irrigated with furrow irrigation thereafter. Plots were two beds wide by 35 ft long and bordered by two untreated beds. Four replications of each treatment were arranged in a RCB design. Formulations and rates for each compound are provided in the tables. All foliar sprays were applied on 1, 13 and 26 Feb. The applications were made with a CO2 pressurized boom sprayer that delivered a broadcast application at 40 psi and 22.5 gpa through 2 TXVS-18 ConeJet nozzles per bed. An adjuvant Dyne-Amic (Helena Chemical Co.), was applied at 0.25% to all treatments. Numbers of WFT from 5 plants per replicate were recorded at various sample dates following each application (DAT). Relative WFT numbers were measured by removing plants and beating them vigorously against a screened pan (12 inch x 7 inch x 2 inch) for a predetermined time (10 s). A 6 inch by 6 inch sticky card was placed inside of the pan to catch the dislodged WFT. Sticky cards were then taken to the laboratory where adult and larvae were counted. Because of heterogeneity of mean variances, data were transformed using a log10 (x + 1) function before analysis and subjected to ANOVA; means were compared using an F-protected LSD (P ≤ 0.05). Means from non-transformed data are presented in the tables.

EVALUATION OF INSECTICIDE SPRAY/NO SPRAY ON CONVENTIONAL AND DOUBLE-GENE INSECT RESISTANT COTTON AGAINST BOLLWORM, 2013

Thirteen double-gene insect resistant and two conventional cotton varieties were evaluated for control of BW in Virginia cotton at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA. Each variety was treated with insecticides targeting BW, or not treated for BW. In the treated plots, double-gene insect resistant varieties received one spray of Brigade @ 6.4 oz/acre plus Belt @ 2 oz/acre on 14 Aug 6 day after BW egg threshold. Conventional varieties received two sprays for BW, Brigade @ 6.4 oz/acre at BW egg threshold on 8 Aug, and Brigade @ 6.4 oz/acre plus Belt @ 2 oz/acre on 14 Aug. Treatments were applied with a Spider Spray Trac-mounted CO2-pressurized sprayer at 16.5 gpa and 30 psi through 8002VS nozzles spaced 18 inches apart on the spray boom. Cotton was planted 17 May using 36-inch row spacing. A split-plot experimental design was used with 4 replicates; plots were 4 rows by 40 ft. Plant population was determined on 24 Jun by counting all plants in two rows per plot. External boll injury was determined by visually inspecting 25 bolls per plot for evidence of BW feeding on three dates. Yield was determined by harvesting 2 rows of each plot (80 row ft) on 13 Nov using a commercial 2-row cotton picker. Samples from each variety were ginned to determine lint versus seed and trash weight. Data were analyzed using ANOVA and LSD statistical procedures.

EVALUATION OF SELECTED INSECTICIDES FOR STINK BUG MANAGEMENT IN VIRGINIA COTTON, 2013

Two tests were conducted to determine efficacy of foliar-applied insecticides against a stink bug complex in cotton. ‘DP 0912 B2RF’ (Test 1) and ‘PHY 499 WRF’ (Test 2) cotton was planted on 15 May (Test 1) and 10 May (Test 2) at the Virginia Tech Tidewater Agric. Res. & Ext. Ctr., Suffolk, VA, using 36-inch row spacing. A RCB experimental design was used with 4 replicates; plots were 4 rows by 35 ft. Treatments in both tests were applied on 29 Jul and 5 Aug with a Spider Spray Trac-mounted CO2-pressurized sprayer at 16.5 gpa and 30 psi broadcast through 8002VS nozzles spaced 18 inches apart on the spray boom, and a third application was made on 12 Aug using the same equipment at 19.9 gpa and 38 psi. Product rates remained the same for all three applications. Ten 0.9 to 1.1-inch-diameter bolls per plot were examined for stink bug feeding injury (i.e., internal warts and stained lint) at multiple days after treatment. Yield was determined by harvesting 2 rows of each plot (70 row ft) using a commercial 2-row cotton picker. Sub-samples were ginned to determine lint versus seed and trash weight. Data were analyzed using ANOVA and LSD statistical procedures.

F55

This test was conducted in a commercial cotton field grown near Lubbock, TX. The field was on 40-inch rows, and was irrigated using furrow irrigation. Plots were 4-rows wide × 50 ft in length. Insecticides were applied with a CO2 pressurized hand-boom sprayer calibrated to deliver 10 gpa through TX-6 hollow cone nozzles (2 per row) at 40 psi. Insecticides were applied to all four rows of each plot. Treatments were evaluated by collecting 5 or 10, mid canopy leaves per plot and returning these to the laboratory where the mites were removed onto a liquid detergent coated glass plate with a mite brush. Mite eggs, larvae and adults were counted from the entire glass plate. Data were analyzed using ANOVA and means were separated using an F-protected LSD (P ≤ 0.05).

Eficácia e pH de caldas de glifosato após a adição de fertilizantes nitrogenados e utilização de pulverizador pressurizado por CO2

Este trabalho foi desenvolvido com o objetivo de avaliar a eficácia e o pH de caldas de glifosato após a adição de fertilizantes nitrogenados e utilização de pulverizador pressurizado por CO2. Em campo, foram aplicadas duas doses de glifosato (360 e 720 g ha-1), isoladas ou combinadas a duas concentrações de ureia (2,5 e 5,0 g L-1) ou sulfato de amônio (7,5 e 15,0 g L-1). Em laboratório, mensurou-se o pH de caldas de glifosato após o uso de diferentes concentrações do produto e dos fertilizantes nitrogenados e após a utilização do pulverizador pressurizado por CO2. Em todas as avaliações do experimento em campo, a menor dose de glifosato teve maior eficácia biológica após a adição de sulfato de amônio (15 g L-1) à calda. A ureia (5 g L-1) proporcionou efeitos benéficos somente na avaliação aos 28 dias após a aplicação. Em laboratório, o aumento da concentração de glifosato promoveu gradativa acidificação da calda de pulverização, com estabilização do pH da solução em 4,5. O sulfato de amônio causou pequena acidificação da calda herbicida, enquanto a ureia não alterou o pH. O uso do pulverizador pressurizado por CO2 pouco alterou o pH da calda de glifosato. A maior eficácia do glifosato após a adição de fertilizantes nitrogenados à calda está pouco relacionada com alterações no pH da solução.

EVALUATION OF NEW MITICIDES FOR SPIDER MITE CONTROL IN COTTON, 2007

This test was conducted in a commercial cotton field grown near Idalou, TX. The field was planted on 40-inch rows, and was irrigated using a subsurface drip irrigation system. The test was a RCB design with four replications. Plots were 4-rows wide × 60 ft in length. Miticides were applied with a CO2 pressurized hand-boom sprayer calibrated to deliver 10 gpa through TX-6 hollow cone nozzles (2 per row) at 40 psi. Insecticides were applied to all four rows of each plot on 4 Aug. A pre-treatment count was made on 3 Aug. Post treatment evaluations were made at 6, 12 and 19 days after treatment (DAT). Treatments were evaluated by collecting 5, mid-canopy leaves per plot and returning these to the laboratory where the mites were removed onto a liquid detergent coated glass plate with a mite brush. Mite eggs, larvae and adults were counted from the middle 1-inch diameter area of the glass plate. Mite population data discussed is the number per 1-inch diameter mite brush sample per leaf. Data were analyzed using ANOVA and means were separated using an F-protected LSD (P ≤ 0.05).

Suscetibilidade de cultivares de arroz irrigado (Oryza sativa) à deriva simulada do herbicida imazethapyr + imazapic

Objetivou-se neste trabalho avaliar a suscetibilidade dos cultivares de arroz irrigado IRGA 417, BR-IRGA 410, BRS Pelota e Qualimax 1 à simulação de deriva do herbicida imazethapyr + imazapic em função da época de início da irrigação por inundação. Para isso, foi conduzido experimento em casa de vegetação do Departamento de Fitossanidade da FAEM/UFPel, na estação de crescimento 2003/04. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. A deriva foi simulada pela aplicação de doses crescentes do herbicida imazethapyr + imazapic, correspondendo a 0; 3,125; 6,25; 12,5; 25; 50; e 100% da dose comercial (100 g ha-1), acrescido de Dash a 0,5% v/v, pulverizados sobre as plantas de arroz em estádios fenológicos V3 - V4, com inundação três dias antes ou após a aplicação dos tratamentos. A aplicação foi realizada com pulverizador costal, pressurizado a CO2, munido de barra com bicos 110.015 do tipo leque a uma pressão constante de 210 kPa, que proporcionou a aplicação de 150 L ha-1 de calda herbicida. A fitotoxicidade ocasionada pelo herbicida foi avaliada de forma visual aos 10, 15 e 20 dias após a aplicação dos tratamentos (DAT), utilizando-se escala percentual. Aos 25 DAT foi determinada a massa seca aérea e radical. O herbicida imazethapyr + imazapic causou fitotoxicidade aos cultivares de arroz IRGA 417, BR-IRGA 410, BRS Pelota e Qualimax 1, em deriva ocorrida em solo seco ou inundado. A massa seca da parte aérea e radical foi reduzida com o aumento da dose aplicada, independentemente da condição de aplicação. O cultivar IRGA 417 foi mais sensível à simulação de deriva de imazethapyr + imazapic.

Efeito de deriva simulada de herbicida inibidor de ALS nos componentes da produtividade do arroz irrigado

O objetivo deste trabalho foi quantificar os efeitos causados pela deriva simulada do herbicida imazethapyr + imazapic nos componentes da produtividade de grãos de arroz irrigado, em função da época de início da irrigação por inundação. Para isso, foi conduzido experimento no ano agrícola 2003/04, em condições de campo, no Centro Agropecuário da Palma (CAP/UFPel). O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. A deriva foi simulada pela aplicação de doses crescentes do herbicida imazethapyr + imazapic, correspondendo a 0; 3,125; 6,25; 12,5; 25; 50; e 100% da dose comercial, acrescido de Dash a 0,5% v/v, sobre as plantas de arroz, cultivar BRS Pelota, em estádios fenológicos V3 - V4, com inundação três dias antes ou após a aplicação dos tratamentos. A aplicação foi feita com pulverizador costal, pressurizado a CO2, munido de barra com bicos 110.015 do tipo leque a uma pressão constante de 210 kPa, que proporcionou a aplicação de 150 L ha-1 de calda herbicida. As variáveis avaliadas foram: número de colmos, em estádio R3, número de grãos por panícula, número de espiguetas estéreis, peso de mil grãos e produtividade de grãos, determinados por ocasião da colheita. O herbicida imazethapyr + imazapic reduziu o número de colmos de arroz, o número de grãos e de espiguetas estéreis por panícula, o peso de mil grãos e a produtividade de grãos com o aumento da dose aplicada, quando esta ocorreu em cultura mantida no seco. A antecipação do início da irrigação por inundação, em lavouras semeadas com cultivar suscetível, evita possíveis prejuízos ocasionados por deriva de imazethapyr + imazapic no número de colmos, número de grãos e espiguetas estéreis por panícula, peso de mil grãos e produtividade de grãos.