Postemergence Herbicide Applications Research Articles

Insecticide Seed Treatments Reduced Crop Injury from Flumioxazin, Chlorsulfuron, Saflufenacil, Pyroxasulfone, and Flumioxazin + Pyroxasulfone + Chlorimuron in Soybean

With increased instances of weed resistance to applications of postemergence herbicides, the use of soil-applied herbicides that offer residual activity is becoming popular. Unfortunately, under some conditions, the use of residual herbicides can result in unintentional injury to crops. However, there are a number of ways to reduce these risks, including the use of in-crop herbicide safeners. Based on previous research conducted on rice, the potential may exist for crop injury from certain soil-applied herbicides to be reduced (safened) in seeds treated with insecticides. Field trials were conducted in Marianna, Arkansas, in 2015 and 2016, and near Colt, Arkansas, in 2016, to explore this possibility in soybean. Soybean seeds were treated with the insecticide thiamethoxam and subsequently the herbicides metribuzin, saflufenacil, pyroxasulfone, sulfentrazone, chlorimuron, flumioxazin, flumioxazin + pyroxasulfone + chlorimuron, mesotrione, and chlorsulfuron were applied immediately after planting. Of the nine herbicides evaluated, the insecticide reduced crop injury for flumioxazin, chlorsulfuron, saflufenacil, pyroxasulfone, and flumioxazin + pyroxasulfone + chlorimuron. The highest degree of injury reduction was seen 1 week after emergence (WAE) at Marianna, where injury from flumioxazin + pyroxasulfone + chlorimuron was reduced from 15% to 5%. Based on the results from this study, the insecticide seed treatment thiamethoxam may have the potential to safen soybean to applications of some soil-applied herbicides.

Efficacy of post-emergence herbicides for weed control in soybean

A field experiment was conducted at Punjab Agricultural University, Ludhiana to study the efficacy of post-emergence herbicides for weed control in soybean. The herbicides (pendimethalin, imazethapyr, imazethapyr + imazamox and quizalofop-p-ethyl) did not show any significant adverse effects on the number, dry weight and leghaemoglobin content of nodules. Application of pendimethalin 0.45 kg/ha as pre-emergence (PE) + hand weeding (HW) at 40 days after sowing (DAS) recorded significantly higher seed yield than other treatments, however, it was at par with two hand weeding. Among the herbicides, imazethapyr at 75 g/ha applied at 3 weeks after sowing (WAS) recorded significantly higher seed yield than pendimethalin 0.45 kg/ha (PE) and weedy check and was at par with imazethapyr + imazamox 70 g/ha and quizalofop-p-ethyl 50 g/ha applied at 3 WAS. Application of pendimethalin 0.45 kg/ha (PE) + HW at 40 DAS provided the highest net returns (` 49496/ha) followed by two hand weedings. However, application of post-emergence herbicides imazethapyr at 75 g/ha and imazethapyr + imazamox 70 g/ha at 3 WAS were found promising in controlling weeds, providing optimum seed yield and higher B: C ratio. In case of scarcity of labour, post-emergence herbicides can play an important role in controlling weeds effectively.

Uticaj vremena uklanjanja korova i pre-em primene herbicida na rast useva soje

Field studies were conducted in 2017 at Concord in northeast Nebraska to evaluate how timing of weed removal and application of pre-emergence (PRE) herbicides influences the growth of soybean. The studies were laid out in a split-plot arrangement of 14 treatments (2 herbicide regimes and 7 weed removal timings) with four replicates. The 2 herbicide regimes were: No PRE and PRE application of a premix of sulfentrazone plus imazethapyr (140 plus 28 g ai ha-1). The 7 weed removal timings were: V1, V3, V6, R2 and R5 soybean growth stages, as well as weed free and weedy season long. Soybean growth parameters (leaf area and dry matter) were collected at R6 growth stage. Delayed timing of weed removal significantly influenced the soybean growth by reducing leaf area and dry matter. Without the application of PRE herbicides, a 5% reduction in soybean leaf area and dry matter occurred when weed removal was delayed until 100 growing degree days after emergence (GDD; equivalent to V1 soybean stage or 10 days after emergence [DAE]). Meanwhile, the use of PRE herbicide prevented the same level of reduction until 382 GDD (V5 soybean stage; 34 DAE). The practical implication is that the use of PRE herbicides protected soybean growth and delayed the need for post-emergence application of herbicides by three weeks after soybean emergence.

Influence of different transplanting date and weed management practices on yield and quality of basmati rice (Pusa Basmati-1509)

A field experiment was conducted during kharif 2014 at students’ farm of Chaudhary Charan Singh Haryana Agricultural University, college of agriculture, Kaul (Kaithal). The experiment consisted of four transplanting dates (June 15, July 5, July 25 and August 15) in main plots and six weed control treatments in sub plots treatments consisted of pre-emergence application of pretilachlor, oxadiargyl alone and sequential application of pre and post emergence herbicides viz., pretilachlor fb bispyribac, oxadiargyl fb bispyribac, weed free check and unweeded check. Based on research investigation it was observed that early transplanting dates (June 15 and July 5) produced taller plant, higher tillers/m2 and crop dry matter accumulation at all growth stages. Early transplanting produced significantly higher number of effective tillers/m2 (263) along with higher number of filled grain/ panicle (85) than delayed planting (July 25 and August 15). The 1000-grain weight was not affected by time of transplanting. The highest grain yield (4363 kg/ha) was recorded under June 15 transplanting which was statistically at par to the grain yield (4058 kg/ha) obtained under July 5 transplanting. Among the weed management practices tried, weed free check resulted in the highest values of plant height (104.2 cm), tillers/m2 (305), crop dry matter accumulation (964 g/ m2), effective tillers/m2 (271), grains length (8.5 cm), filled grains/panicle (86.3) as well as grain (4516 kg/ha) and straw yield (5506 kg/ha) which were however, comparable to pre-emergence application of oxadiargyl followed by bispyribac-sodium applied at 25 DAT and pretilachlor followed by bispribac-sodium at 25DAT.

HERBICIDE SELECTIVITY TO SIGNAL GRASS AND CONGO GRASS

ABSTRACT This study was conducted in order to evaluate the selectivity of signal grass and congo grass, submitted to post-emergence herbicide application. The experiment was conducted under greenhouse conditions, in Diamantina, Minas Gerais state, and it was arranged in a randomized block design, with five replications. Treatments were set in factor scheme (8 x 2) + 2. Eight herbicides (nicosulfuron; clomazone; glyphosate; fluazifop-p-butyl + fomesafen; lactofen; fomesafen; fluazifop-p-butyl and mesotrione) were applied in doses recommended by the manufacturer on two fodder species: Brachiaria decumbens cv. Basilisk (signal grass) and Brachiaria ruziziensis (congo grass); in addition, there were two control samples without herbicide application, for a total of 18 treatments. The evaluated herbicides showed less intoxication on signal grass when compared to congo grass. Nicosulfuron and glyphosate promoted higher intoxication on both species when compared to the other herbicides. Glyphosate, fluazifop-p-butyl + fomesafen, fluazifop-p-butyl, mesotrione and nicosulfuron affected the ratio variable / maximum fluorescence (Fv/Fm) in both species, indicating an effect provided by these herbicides on the electron transport chain. Results demonstrated that signal grass and congo grass have higher susceptibility to glyphosate, fluazifop-p-butyl + fomesafen, fluazifop-p-butyl, mesotrione and nicosulfuron. congo grass shows higher susceptibility to the studied herbicides when compared to signal grass.

Herbicide sequence for weed management in direct seeded rice

An experiment was conducted during Kharif 2014 and 2015 at Agricultural Research Station, Dhadesu-gur, University of Agricultural Sciences, Raichur, Karnataka, India, to know the herbicide sequence for weed man-agement in direct seeded rice. The dominant weeds in direct seeded rice were Echinochloa sp, Panicum repens, Cynodon doctylon, Leptochloa chinensis, Bracharia sp. Ludwigia parviflora, Commelena sp. and Cyperus sp. Pooled data revealed that, application of pyrazosulfuron ethyl 10 % WP at 20 g a.i./ha as pre-emergent herbicide followed by the application of Bispyribac sodium 10 % SC @ 250 ml/ha at 20 to 25 days after sowing as post-emergent herbi-cide in direct seeded rice was most effective in controlling of grasses, broad leaf weeds and sedges and increased the rice grain yield (5583 kg/ha) without any phytotoxic effect and which was onpar with the application of Pendime-thalin 30 EC @ 1 kg a.i. /ha as pre-emergent herbicide followed by one hand weeding at 30 days after sowing and weed free check .Therefore, the application of pre emergent herbicides followed by the post emergent herbicide application can reduce the weed problem in direct seeded rice.

Control of mixed weed flora in wheat with sequential application of pre-and post-emergence herbicides

The field efficacy of pre-and post-emergence herbicides for control of mixed weed flora in wheat was evaluated in a field study conducted at Punjab Agricultural University, Ludhiana during Rabi seasons of 2014–15 and 2015–16. The season long growth of weeds reduced wheat yield upto 38.5%. Pendimethalin and metribuzin recorded 65–73 and 73–78% control of Phalaris minor, respectively and their tank-mix application enhanced P. minor control to 78–85%. Pendimethalin and metribuzin recorded 26–33 and 5863% control of Medicago denticulata, respectively and their tank-mix application enhanced control to 77–92% of this weed. Pendimethalin and metribuzin provided control of Rumex dentatus to the extent of 98–100% and 68–92%, respectively, while provided 98–100 and 63–72%, respectively control of C. album. Sequential application of pendimethalin as pre-emergence followed by sulfosulfuron as post-emergence recorded the highest weed control efficiency (96%) and wheat grain yield (4.8 t/ha), and it was at par to pre-emergence pendimethalin + metribuzin, post-emergence pinoxaden + metsulfuron, mesosulfuron + iodosulfuron, sulfosulfuron + metsulfuron and two hand weeding.

Sequential application of pre-and post-emergence herbicides to control mixed weed flora in maize

A field experiment was laid out in randomized block design with ten weed management practices to determine the bioefficacy of PoE herbicides, halosulfuron-methyl 67.5 g/ha and tembotrione 100 g/ha alone or tank mix and sequential application after PE application of alachlor 1000 g/ha, besides two hand weedings and unweeded control. The broadspectrum weed control and the highest grain yield of rainy season maize was obtained with sequntial application of alachlor 1000 g/ha as PE fb PoE application of halosulfuron-methyl 67.5 g/ha + tembotrione 100 g/ha (tank mix). Post-emergence application of halosulfuron-methyl 67.5 g/ha effectively controlled purple nutsedge.

Assessing the Potential for Fluridone to Reduce the Number of Postemergence Herbicide Applications in Glyphosate-Resistant Cotton

With the evolution of glyphosate-resistant weeds, cotton producers now rely on multiple applications of soil-residual herbicides tank-mixed with postemergence (POST) herbicides. However, the current soil-residual herbicides represent a relatively low number of herbicide mechanisms of action (MOAs), with the same few MOAs being utilized year after year. Therefore, it is important to introduce new MOAs to slow the likelihood of further resistance development. A field experiment was conducted in 2012 and 2013 to determine if fluridone, a bleaching herbicide currently not used in any agronomic cropping system, applied preemergence (PRE) would provide effective season-long control of Palmer amaranth as well as reduce the number of POST applications throughout the season. Fluridone PRE at 224, 336, and 448 g ai ha-1 did not eliminate the need for POST herbicides for Palmer amaranth control in cotton in either year. Fluridone, regardless of rate, provided comparable control to fluometuron in 2012; however in 2013, fluometuron provided less control than fluridone. Although moderate season-long control was observed in 2013, greater seed cotton yields were obtained in 2013 than in 2012, which is likely a result of greater control during the critical period for weed control. Based on this experiment, fluridone will not provide effective season-long Palmer amaranth control in the absence of a multiple POST-herbicide program.

Spatial Pattern of Weeds Based on Multispecies Infestation Maps Created by Imagery

Weeds are often spatially aggregated in maize fields, and the level of aggregation varies across and within fields. Several annual weed species are present in maize fields before postemergence herbicide application, and herbicides applied will control several species at a time. The goal of this study was to assess the spatial distribution of multispecies weed infestation in maize fields. Ground-based imagery was used to map weed infestations in rain-fed maize fields. Image segmentation was used to extract weed cover information from geocoded images, and an expert-based threshold of 0.102% weed cover was used to generate maps of weed presence/absence. From 19 site-years, 13 (68%) demonstrated a random spatial distribution, whereas six site-years demonstrated an aggregated spatial pattern of either monocotyledons, dicotyledons, or both groups. The results of this study indicated that monocotyledonous and dicotyledonous weed groups were not spatially segregated, but discriminating these weed groups slightly increased the chances of detecting an aggregated pattern. It was concluded that weeds were not always spatially aggregated in maize fields. These findings emphasize the need for techniques allowing the assessment of weed aggregation prior to conducting site-specific weed management.

Assessing the potential of images from unmanned aerial vehicles (UAV) to support herbicide patch spraying in maize

The capability of images acquired from unmanned aerial vehicles (UAVs), with multispectral cameras, to detect weed patches, should be tested in operational situations of site-specific weed management. In this regard, different post-emergence herbicide application strategies were evaluated on a total of four silage maize fields in Central Italy. The treatments compared were uniform blanket application, patch spraying according to the application map and an untreated control (the latter treatment only in the second year). Images were acquired a few weeks after maize emergence and were processed into application (i.e. prescription) maps. The accuracy of prescription maps was evaluated on the basis of ground-truth data. Maize and weed biomass data collected at end of the growing season were used to assess differences among the herbicide application strategies. Results showed no differences between uniform and patch spraying treatments for silage maize biomass in the two fields of the first year. In the second year, maize biomass differences were observed between the untreated control and the other two treatments. In terms of weed biomass there were no differences among treatments, for three out of four fields. The use of UAV image data captured early post-emergence in maize lead to a decrease in the use of herbicide without negative consequences in terms of crop yield and, at the same time, increased the silage biomass production as compared to non-treated area. The saving of herbicide calculated in terms of untreated area ranged between 14 and 39.2 % for patch spraying as compared to a uniform blanket application, and saved between 16 and 45 € ha−1.

Weed management using crop competition in the United States: A review

Exploiting the competitive ability of crops is essential to develop cost-effective and sustainable weed management practices. Reduced row spacing, increased seeding rates, and selection of competitive cultivars can potentially manage crop–weed competition in cotton, soybean, wheat, and corn. These cultural weed management practices facilitate a more rapid development of crop canopy that adversely affect the emergence, density, growth, biomass, and subsequently the seed production of weeds during a growing season. These cultural practices can also favour the weed suppressive ability of the crop by influencing the canopy architecture traits (plant height, canopy density, leaf area index, rate of leaf area development, and leaf distribution). These crop-competition attributes can potentially reduce the risk of crop yield losses due to interference from weed cohorts that escape an early- or a late-season post-emergence herbicide application. Furthermore, reduced row spacing, increased seeding rates, and weed-competitive cultivars are effective in reducing reliance on a single site-of-action herbicides, thereby reducing the selection pressure for development of herbicide-resistant weed populations in a cropping system.

Optimizing plant density and weed control techniques in yield enhancement of mungbean

Field experiment was carried out at the Agronomy farm, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to investigate the effect of plant density and weed control techniques on yield enhancement of mungbean. The experiment consisted of two factors viz. plant densities and weed control. Plant densities were 30 cm×continuous (D1), 30 cm×5 cm (D2), 30 cm×10 cm (D3) and 30 cm×15 cm (D4) arranged in the main plot. Weed control techniques were no weeding (W0), two hand weeding at 15 and 30 DAS (W1), Topstar 80 WP @ 75 g ha-1 as pre-emergence at 3 DAS (W2) and Whip Super 9 EC @ 750 ml ha-1 at 15 and 30 DAS as post-emergence herbicide (W3) arranged in the sub plot in a split plot design. Results showed that both plant density and weed control techniques significantly influenced most of the parameters studied. It was observed that application of pre and post emergence herbicide controlled weeds effectively compared to other weed control techniques whereas weed population and weed biomass were less in 30 cmx10 cm plant density. Considering yields, combination of 30 cm×10 cm plant density with application of Topstar 80 WP (D3W2) attributed to highest seed yield (1.47 t ha-1), stover yield (1.94 t ha-1) and biological yield (3.41 t ha-1) of mungbean.J. Asiat. Soc. Bangladesh, Sci. 42(1): 107-114, June 2016

Growth and development of fall- and spring-planted populations of Conyza canadensis and C. bonariensis

ABSTRACTThe growth and phenological development of spring- and fall-planted Conyza canadensis and C. bonariensis were studied in Fresno, CA, USA. A glyphosate-resistant (GR) and a glyphosate-susceptible (GS) population of each species were used. Time taken by each plant to reach the rosette, bolting, appearance of first bud, appearance of first open flower, and initial seed set were converted to growing degree days (GDDs). The fall- and spring-planted C. canadensis required similar GDDs to complete their life cycles but the GR type required fewer GDDs than the GS type. In C. bonariensis, the GDDs required to complete its life cycle differed between the fall- and spring-plantings but not between the GR and GS types. The total aboveground biomass of both fall- and spring-planted Conyzas at initial seed set was similar but the spring-planted GS C. canadensis produced more biomass than the GR type, whereas the fall-planted GS C. bonariensis produced more biomass than the GR type. Plant development based on GDD models can have global implications and help in planning for timely applications of post-emergence herbicides.

Penggunaan Herbisida untuk Pengendalian Gulma pada Budi Daya Kedelai Jenuh Air di Lahan Pasang Surut

Weed is a problem on the soybean saturated culture in tidal swamp land. The objective of this study was to obtain the most effective herbicide for weed control on soybean planted under saturated culture in the tidal swamp land. Research was conducted in tidal swamp land at Banyu Urip village, Tanjung Lago districs, Banyuasin, South Sumatra Province, from July to December 2013, using a randomized block design consisted, of the eight treatments, with three replications. The treatments were: control (P0), manual weeding 4 weeks after planting (P1), paraquat 2 l/ha 4 weeks after planting (P2), glyphosate 3 l/ha 4 after planting (P3), oxyfluorfen 2 l/ha 3 days before planting (P4), oxyfluorfen 3 days before planting 2 l/ha followed application of paraquat 4 weeks after planting 2 l/ha (P5), oxyfluorfen 3 days before planting 2 l/ha followed application of glyphosate 4 weeks after planting 3 l/ha (P6), penoxulam 1 l/ha 2 weeks after planting (P7). Results showed that herbicide paraquat effectively suppressed total dry weight of weeds at 4, 6, and 8 weeks after planting. Cyperus iria was the most dominant weed in the field, with Sum Dominance Ratio 37.7%. The highest soybean productivity was 3.7 t/ha obtained from glyphosate treatment. Pre-emergence herbicide applications should be done prior to soybean planting and the post-emergence herbicide application must be done carefully by using nozzle lid to prevent toxicity to the crop plants.

Weed Phytosociological and Floristic Survey in Agricultural Areas of Southwestern Goiás Region

The use of the Roundup Ready(r) technology and the cultivation of a second crop influence the floristic composition of weed communities in Brazilian Central-West region cropping systems. This study has aimed to diagnose the dominant weed species in southwestern Goiás in areas of genetically-modified and conventional soybeans, using phytosociological and floristic surveys. Weed sampling was obtained by collecting all the plants present within a 0.5 m hollow frame, randomly thrown 20 times in each of thirty-five agricultural areas in the 2012/2013 harvest. Field survey was carried out in three periods: before desiccation for soybean sowing, before postemergence herbicide in soybean first application and before postemergence herbicide application in late harvest. A total of 525 m2 was inventoried and 3,219 weeds were collected, which included 79 species, 58 genera and 28 families. Families Poaceae, Asteraceae, Euphorbiaceae, Fabaceae, Amaranthaceae, were the most representative in the survey. Species Cenchrus echinatus, Glycine max, Chamaesyce hirta, Commelina benghalensis, and Alternanthera tenella stood out in importance. The RR+millet soybean treatment had the highest number of species (44), while the conventional soybean + sorghum treatment had the lowest number of species (18). The highest number of species was recorded in first sampling period. Treatments conventional soybean + maize and conventional soybean + millet showed higher similarity (70%), while treatments RR soybean + millet and conventional soybean + sorghum showed the least (51%). Species of difficult control were recorded in all cultivation systems analyzed.

Herbicide coverage in narrow row soybean as influenced by spray nozzle design and carrier volume

The use of reduced drift nozzles that produce larger droplet sizes that are less prone to drift will likely be required for use of future postemergence herbicide applications in soybean in the USA. Experiments to evaluate the effect of reduced drift spray nozzles on spray solution coverage were conducted in the field in Indiana. Air induction extended range (AIXR) and turbo TeeJet air induction (TTI) nozzles that produce extremely coarse to ultra coarse droplets were compared to extended range (XR) and Turbo TeeJet (TT) nozzle that produced fine to coarse droplets. Each nozzle was evaluated for spray coverage at 94 and 140 l ha−1 spray volumes using water sensitive cards. Precipitation varied between site years and resulted in differences in soybean canopy development and spray solution coverage. Coverage was greater at the top of the canopy than at the bottom of the soybean canopy as expected. An interaction occurred at the top and middle of the canopy in which the AIXR and TTI nozzles had similar coverage between the two spray volumes, whereas the XR and TT nozzles had greater coverage at 140 l ha−1 carrier volume than 94 l ha−1 carrier spray volume. Spray solution coverage at the bottom of the canopy, where target weeds would be, was similar between all nozzle types. Coverage was greater at the bottom of the canopy at 140 l ha−1 spray volume than with the 94 l ha−1 carrier volume. Spray volume has a greater influence on coverage than spray nozzle type and AIXR and TTI nozzles are less prone to coverage differences due to spray volume than the XR and TT nozzles.

Invasion of Different Weeds on Gladiolus and their Control by Herbicides

Weeds are defined as plants growing where they are not desired. Presence of weeds highly effects the growth and development of desirable plants. Present study was carried out at Floriculture Research Area, University of Agriculture Faisalabad. The experiment was laid out in randomized complete block design with three replications. Five herbicide treatments were applied in three replications to the gladiolus variety “white prosperity”. By comparing results of pre and post emergence herbicide applications, it was observed that pre emergence treatments gave better results regarding weed control due to reduced competition between weed plants and crop plants. Pendimethalin applied at 12ml/litre was found to be the most effective treatment and controlled all weeds except Cyperus rotundus . Average number of plants and weed inhibition percentage of Cyperus rotundus in one foot square area were, 15.22 (39%), Convolvulus arvensis , 0.89 (77%), Coronopus didymus , 0.33 (91%), Chenopodium album , 0.22 (98%), Anagallis arvensis , 0.22 (98%), Conyza stricta , 0.89 (85%), Stellaria media , 0.22 (98%), Poa annua , 0.0 (100%), Melilotus indica , 0.22 (98%). Study revealed that Cyperus rotundus was efficiently controlled by S metolachlore than Pendimethalin where only average (2.22) numbers of plants were found in one square foot area and best weed inhibition percentage was upto (91%) for Cyperus rotundus.

Herbicide combinations for weed management in transplanted rice

A field experiment was conducted during 2012–13, to study the effect of herbicides applied in mixture and sequence for managing complex weed flora in transplanted rice. Among the herbicides applied, bispyribac-Na applied in combination with almix as tank mixture recorded the least weed count, weed dry matter and highest WCE. Significantly higher yield attributes, viz. number of grains/panicle and grain yield were also recorded when bispyribac-Na and metsulfuron-methyl + chlorimuron-ethyl were applied as tank mixture. Pre-emergence application of pretilachlor fb post-emergence application of metsulfuron-methyl + chlorimuron-ethyl and hand weeding twice at 25 and 45 DAT were also equally effective. Application of pre-and post-emergence herbicide alone were found to be less effective in reducing weed density and weed dry matter.

Effect of different doses of post-emergence-applied iodosulfuron on weed control and grain yield of malt barley (Hordeum distichum L.), under Mediterranean conditions

AbstractA study was carried out over a two year period (2009/2010 and 2012/2013) on an experimental farm in the Alentejo region (Beja), in southern Portugal where rainfed malt barley (Hordeum distichum L.) is sown at the end of autumn or beginning of winter (November- December). The aim of this experiment was to study the efficiency of the herbicide iodosulfuron-methyl-sodium to control post-emergence broadleaved weeds in this cereal crop. The malt barley crop was established using no-till farming. This technology provides the necessary machine bearing capacity of the soil to assure the post-emergence application of herbicides at two different weed development stages. The herbicide iodosulfuron-methyl-sodium was applied at three doses (5.0, 7.5, and 10.0 g a. i. · ha-1) and at two different broadleaved weed development stages (3 to 4 and 6 to 7 pairs of leaves), that also corresponded to two different crop development stages (beginning of tillering and complete tillering). The results indicated that early herbicide application timing provided a significantly higher efficiency for all the applied herbicide doses, but this better weed control was not reflected in a higher crop grain yield. The lack of a higher crop grain yield was probably due to a crop phytotoxicity of the herbicide, when used at an early application timing.