Preemergence Research Articles

Weed dynamics, productivity and economics of quality protein maize (Zea mays) as affected by weed and nutrient-management

A field experiment was conducted during 2015–16 and 2016–17 at Instructional Farm (Agronomy), Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan, to evaluate the effect of weed and nutrient-management on quality protein maize. The experiment consisting of 9 weed-management treatments, viz. weedy check, hand-weeding at 15 days after sowing (DAS) and 35 DAS, tembotrione 0.125 kg/ha at 20 DAS, alachlor 2 kg/ha as pre-emergence (PE) followed by (fb) hand-weeding at 35 DAS, atrazine 0.5 kg/ha as PE fb hand-weeding at 35 DAS, tembotrione 0.125 kg/ha at 20 DAS fb hand-weeding at 35 DAS, alachlor 2 kg/ha + atrazine 0.5 kg/ha as PE fb hand-weeding at 35 DAS, alachlor 2 kg/ha as PE fb tembotrione 0.125 kg/ha at 20 DAS and atrazine 0.5 kg/ha as PE fb tembotrione 0.125 kg/ha at 20 DAS with 3 nutrient-management treatments, viz. NPK, NPK + Zn and NPKS + Zn, were replicated thrice in a split-plot design. The maximum reduction of weed density (8.35) and dry-matter (133.6 g) was recorded with atrazine 0.5 kg/ha fb tembotrione 0.125 kg/ha. Atrazine 0.5 kg/ha fb tembotrione 0.125 kg/ha resulted in maximum number of grains/ cob (367.91), grain weight (82.79 g), 1,000-seed weight (212.03 g) and shelling % (76.58) and ensued significantly higher grain (4.5 t/ha) and stover (7.5 t/ha) yields. Application of NPKS + Zn showed significantly higher yield attributes as well as grain (4.3 t/ha) and stover (7.2 t/ha) yield.

Preemergence herbicide premixes reduce the risk of soil residual weed control failure in corn

AbstractWidespread occurrence of herbicide-resistant weeds and more variable weather conditions across the United States has made weed control in many crops more challenging. Preemergence (PRE) herbicides with soil residual activity have resurged as the foundation for early season weed control in many crops. Field experiments were conducted in Janesville and Lancaster, Wisconsin, in 2021 and 2022 (4 site-years) to evaluate the weed control efficacy of solo (single site of action [SOA]) and premix (two or more SOAs) PRE herbicides in conventional tillage corn. Treatments consisted of 18 PRE herbicides plus a nontreated check. At the Janesville-2021 site, S-metolachlor + bicyclopyrone + mesotrione, atrazine + S-metolachlor + bicyclopyrone + mesotrione, and clopyralid + acetochlor + mesotrione provided >72% giant ragweed control. At the Janesville-2022 site, none of the PRE herbicides evaluated provided >70% giant ragweed control due to the high giant ragweed density and the lack of timely rainfall. At the Lancaster-2021 site, atrazine, dicamba, and flumetsulam + clopyralid provided <45% waterhemp control, but the remaining treatments provided >90% control. At the Lancaster-2022 site, the efficacy of some PRE herbicides was reduced due to the high waterhemp density; however, most herbicides provided >75% control. At the Lancaster-2021 and Lancaster-2022 sites, only dicamba and S-metolachlor did not provide >75% common lambsquarters control. Group 15 PRE herbicides provided >75% control of giant foxtail. Across weed species, PRE herbicides with two (78%) and three (81%) SOAs provided greater weed control than PRE herbicides with a single SOA (68%), indicating that at least two SOA herbicides applied PRE result in better early season weed control. The efficacy of the PRE herbicide treatments evaluated herein varied according to the soil seedbank weed community composition and environmental conditions (i.e., rainfall following application), but the premixes were a more reliable option to improve early season weed control in conventional tillage corn.

Physiological Parameters and Yield of Green Gram As Influenced By Weed Management Practices

A field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli during Summer, 2021 to evaluate the weed management practices in green gram. The study comprised of eleven weed management practices with different combination viz., pre emergence (PE) application of Diclosulam at 17.5 g/ha, Pendimethalin + Imazethapyr 1 kg/ha, post emergence (POE) application of Fluazifop-p-butyl + Fomesafen 313 g/ha, Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Diclosulam 17.5 g/ha fb POE Fluazifop-p-butyl + Fomesafen 313 g/ha , PE Pendimethalin + Imazethapyr 1 kg/ha fb POE Fluazifop-p-butyl + Fomesafen 313 g/ha, PE Diclosulam 17.5 g/ha fb POE Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Pendimethalin + Imazethapyr 1 kg/ha fb POE Acifluorfen sodium + Clodinofop propargyl 187.5 g/ha, PE Pendimethalin1 kg/ha fb HW on 30 DAS, HW on 20 and 40 DAS and unweeded control (UWC) in green gram. The results revealed that the highest plant height, number of branches plant-1, DMP, LAI, CGR, RGR and NAR were registered in PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1. The grain and haulm yields were also higher in PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1 and it was on par with PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Acifluorfen sodium + Clodinofop propargyl at 187.5 g ha-1. Hence, application of PE Pendimethalin + Imazethapyr at 1 kg ha-1 fb POE Fluazifop-p-butyl + Fomesafen at 313 g ha-1 was found to be the most viable option for getting higher growth and yield in green gram.

Response of Sesame to Different Weed Management Pratices in Maharashtra, India

The experiment was conducted at Agricultural Research Station, Jalgaon, Maharashtra during Kharif season of 2018 to 2020 to study the effect of pre and post emergence herbicide on growth and yield of sesame. The experiment was laid out in a Randomized Block Design (RBD), replicated thrice with eight treatments viz., T1 Weedy check, T2 Weed free, T3 Pendimethalin 30EC (pre–emergence)@0.50kg a.i./ha., T4 Quizlofop-ethyl 5 % EC (post emergence) 50g a.i/ha.at 20 DAS., T5 Sodium Acifluorfen16.5% + Clodinafop-propargyl 8% (premix) @ 100 g.a.i./ha.at 20 DAS., T6 Pendimethalin 30EC (pre–emergence)@ 0. 50 kg a.i./ha.+ Hand weeding at 20DAS., T7 Pendimethalin 30EC (pre–emergence)@0. 50 kg a.i./ha.+ Quizlofop-ethyl 5 % EC (post emergence) 50g a.i/ha.at 20 DAS., T8 Pendimethalin 30EC (pre–emergence) @ 0. 50 kg a.i./ha.+ Sodium Acifluorfen16.5% +Clodinafop-propargyl 8% (premix) @ 100 g.a.i./ha. at 20 DAS.From the pooled results,it is concluded that pre and post emergance herbicide for chemical weed management in sesame, the seed yield were found to be significant.The practice of the treatment T2 (weed free) crop produced the significantly highest seed yield 607 Kg./ha, Net Monetory Returns Rs. 42730/- and B:C Ratio 2.93, over rest of treatment, followed by 523 kg/ha seed yield, Rs. 35873/- Net Monetory Returns and 2.77 B:C ratio by the treatment i.e. pre–emergence application of Pendamethalin 30 EC @ 0. 50 kg a.i./ha + Hand weeding at 20 DAS was an efficient and economically feasible package to manage the weeds and realize better returns.

Effect of Integrated Weed Management Practices on Growth, Physiology and Yield of Direct Sown Finger Millet (Eleusine coracana L.)

To determine “Effect of integrated weed management practices in direct sown finger millet”. The field experiment was conducted during rabi 2022 at South Farm, Karunya Institute of Technology and Sciences, Coimbatore. The soil of the experimental field was sandy clay loam in texture, pH 6.9, level of organic content (0.37%), available N (336 kg ha-1), P (91 kg ha-1) and K (261 kg ha-1). The experiment was laid out in completely randomized block design. T1 (PE pendimethalin @ 0.75 kg ha-1 8 DAS + Hand weeding (HW) @ 35 DAS), T2 (PoE 2,4-D @ 2 kg ha-1 40 DAS + Hand weeding (HW) @ 35 DAS), T3 (PE pretilachlor @ 0.75 kg ha-1 8 DAS + Hand weeding (HW) @ 35 DAS), T4 (PoE 2,4-D @ 2 kg ha-1 40 DAS + Twin wheel hoe weeding (TWHW) @ 30 DAS), T5 (PE pendimethalin @ 0.75 kg ha-1 8 DAS + Twin wheel hoe weeding @ 30 DAS), T6 (PE pretilachlor @ 0.75 kg ha-1 8 DAS + Twin wheel hoe weeding (TWHW) @ 30 DAS), T7 (Hand weeding (HW) @ 25 and 40 DAS), T8 (Twin wheel hoe weeding (TWHW) @ 25 and 40 DAS), T9 (Hand weeding (HW) @ 25 DAS + Twin wheel hoe weeding (TWHW) @ 40 DAS), T10 (Unweeded control). The result shows that the weed control practices significantly decreases weeds also higher control of weed infestation was observed in PE pretilachlor @ 0.75kg ha-1 8 DAS + Twin wheel hoe weeding @ 30 DAS. The maximum dry matter production, CGR, RGR, NPK uptake and grain yield (2368 kg ha-1) were also found higher in PE pretilachlor @ 0.75kg ha-1 8 DAS + Twin wheel hoe weeding @ 30 DAS. From this study it is concluded that application of pre emergence herbicide pretilachlor along with twin wheel hoe weeder increases the crop growth and yield.

Growth and Yield Attributes of Groundnut (Arachis hypogaea L.) as Influenced by Tank-mix Application of Early Post Emergence Herbicides

Background: Groundnut or peanut (Arachis hypogaea L.) is known as the ‘king’ of oilseeds. It is one of the most important food and cash crop of India. Among different constraints that limit the productivity of groundnut, weed menace is one of the serious bottlenecks. A field experiment was conducted at Perunthalaivar Kamaraj Krishi Vigyan Kendra, Puducherry during 2019 to 2020 to study the tank mix application of post-emergence herbicides for efficient weed control in Groundnut. Methods: The experiment was laid out in randomized block design with 13 treatments and replicated thrice. The treatments consisted of weed management practices viz., pre emergence herbicide pendimethalin and post emergence herbicide viz., imazethapyr, quizalofop-ethyl and those herbicides used either alone or combined with hand weeding once. In addition, hand weedings twice at 15 and 30 DAS were tested with unweeded check. Result: The experiment results of the two years study revealed that the Pendimethalin @ 1.5 kg ai ha-1 (PE) + tank mix of Imazethpyr (40%) + Quizalofop ethyl (60%) at 20-30 DAS recorded maximum plant height (58.17 cm), DMP (36.81 g plant-1), Significantly higher pod yield (3752 kg ha-1), highest net income (₹ 90,762 ha-1) and B:C ratio (2.80). Correlation and Regression analysis also indicated that the yield attributes had a positive impact on groundnut yield.

Influence of Weed Management Practices on Growth and Yield of Aerobic Rice

The present field experiment was conducted to evaluate the effects of different chemical and non-chemical weed management practices on aerobic rice. The experiment was carried out at the Wetlands Farm of the Department of Farm Management, Tamil Nadu Agricultural University, India. Pre emergence (PE) application of pendimethalin (1.0 kg ha-1), EPOE of bispyribac sodium (25 g ha-1) and EPOE of chlorimuron ethyl + metsulfuron methyl (4 g ha-1) were the chemical weed management practices. Daincha intercropping (1:1) fb spreading on 30DAS, Cowpea intercropping (1:1) fb spreading on 30DAS, Coir pith mulching (5 tons ha-1) on 3 DAS, Shredded coconut waste mulching (5 tons ha-1) on 3 DAS along with the combination of mechanical and hand weeding were the non chemical weed management practices. Pre emergence (PE) application of pendimethalin (1.0 kg ha-1) on 3 DAS fb Early post emergence (EPOE) application of bispyribac sodium (25 g ha-1) on 20 DAS recorded significantly higher growth and yield attributes. Sequential application of pendimethalin and bispyribac sodium recorded 4128 kg ha-1 grain yield which was nearly 60 per cent increased over the weedy check. Coir pith mulching @ 5 tons ha-1 on 3 DAS recorded significantly lower grain yield (1840 kg ha-1) over the rest of the treatments.

Yield and Nutrient Uptake of Green Gram (Vigna radiata L.) and Weeds as Influenced by Different Integrated Weed Management Practices in Western Uttar Pradesh

The field experiment was conducted at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture & Technology in Meerut (U.P.) during kharif 2021 to assess the performance of post-emergence application of Imazethapyr and Quizalofop-ethyl in combination with pre-emergence application of Pendimethalin on green gram (Vigna radiata L.). The experiment laid out in randomized block design with three replications and comprised of treatments Control (Weedy check) T1, Weed free T2, One hand weeding 20 DAS T3, Two hand weeding 20 and 40 DAS T4, Quizalofop-ethyl 50g a.i./ha Post-emergence (20 DAS) T5, Quizalofop-ethyl 50g a.i./ha Post-emergence (20 DAS) + one hand weeding 40 DAS T6, Imazethapyr 50g a.i./ha Post emergence (20 DAS) T7, Imazethapyr 50g a.i./ha 20 DAS + one hand weeding 40 DAS T8, Pendimethalin 1.0kg a.i./ha Pre emergence T9 and Pendimethalin 1.0kg a.i./ha Pre emergence + Imazethapyr 50g a.i./ha 20 DAS + one hand weeding 40 DAS T10. Treatments effects were evaluated in terms of weed dynamics growth and yield of green gram. The highest total NPK content and uptake by grain and straw found with weed free treatment followed by Pendimethalin 1.0kg a.i./ha Pre emergence + Imazethapyr 50g a.i./ha 20 DAS + one hand weeding 40 DAS was at par with Imazethapyr 50g a.i./ha 20 DAS + one hand weeding 40 DAS. Among the herbicides, the lowest total NPK content and uptake by weed was found with the application of Pendimethalin 1.0kg a.i./ha Pre emergence + Imazethapyr 50g a.i./ha 20 DAS + one hand weeding 40 DAS. The results revealed that treatment T2 (weed free) had the best financial return (Rs 91250 ha-1) and B:C ratio (2.72), while among the herbicides treatment T10 and T8 had the highest net financial return (Rs 92706 ha-1) and B:C ratio (3.14) respectively.

Effect of different Doses and Time of Applications of Topramezone on Weed Dynamics, Growth and Yield of Chickpea (Cicer arietinum L.) in Bihar (India)

Aims: To study the different levels of doses and time applications of topramezone on weed, growth and yield of chickpea (Cicer arietinum L.) in Bihar.
 Place and Duration of Study: Agronomy research farm of Tirhut College of Agriculture, Dholi, Muzaffarpur (Bihar), during the rabi 2020-21.
 Methodology: The experiment was carried out in an RBD design with three replications and ten treatments: topramezone (20.6 and 25.7 g/ha) applied at 14, 21, and 28 DAS, and quizalofop-p-ethyl (100 g/ha) applied at 25 DAS as post-emergence (PoE), pre-emergence (PE) application of valor 1000 g/ha + one hand weeding (HW) at 30 DAS, weed-free control (WFC), and weedy check.
 Results: PE application of valor 1000 g/ha + one HW 30 DAS recorded maximum plant height, number of branches/plants, plant dry matter, seed and straw yield while registered lowest weed dry weight and WCE as compared to all other herbicide treatments. Among all PoE-treated treatments, spray of topramezone (25.7 g/ha) after 21 days of sowing recorded maximum of all these growth parameters at harvest and lowest weed dry matter and highest WCE as compared to other PoE applications.

Planting into a living cover crop alters preemergence herbicide dynamics and can reduce soybean yield

AbstractCereal rye cover crop (cereal rye) and preemergence (PRE) herbicides are becoming common practices for managing herbicide-resistant weeds in soybean production. Adopting these two practices in combination raises concerns regarding herbicide fate in soil, given that the cereal rye biomass can intercept the herbicide spray solution, preventing it from reaching the soil. Delaying cereal rye termination until soybean planting (planting green) optimizes biomass accumulation but might also increase PRE interception. To better understand the dynamics between cereal rye and PRE herbicides, a field experiment was conducted to evaluate two soil management practices (tillage and no-till) and two cereal rye termination practices in the planting-green system (glyphosate [1,260 g ae ha−1] and roller-crimper) on the spray deposition and fate of PRE herbicides and soybean yield. The spray deposition was assessed by placing water-sensitive paper cards on the soil surface before spraying the PRE herbicides (sulfentrazone [153 g ai ha−1] + S-metolachlor [1,379 g ai ha−1]). Herbicide concentration in soil (0 to 7.6 cm) was quantified 25 d after treatment (DAT). The presence of no-till stubble and cereal rye biomass reduced the spray coverage compared to tillage at PRE application, which reflected in a reduction in the concentration of both herbicides in soil 25 DAT. Soybean yield was reduced in all three years when the cereal rye was terminated with a roller-crimper but only reduced in one year when terminated with glyphosate. Our findings indicate that mainly cereal rye biomass reduced the concentration of PRE herbicides in the soil due to the interception of the spray solution during application. Although higher cereal rye biomass accumulation can provide better weed suppression according to the literature, farmers should be aware that the biomass can lower the concentration of PRE herbicides reaching the soil, thus intensifying field scouting to ensure that weed control is not being negatively affected.

Dose-response of five weed species to indaziflam and oxadiazon

AbstractIndaziflam and oxadiazon are efficacious preemergence herbicides used in warm-season turfgrass because of their persistence and residual activity. It is beneficial to quantify effective concentrations for preemergence control of summer annual weeds and determine whether these concentrations are maintained throughout weed emergence periods. Therefore, greenhouse bioassays were conducted with barnyardgrass, broadleaf signalgrass, doveweed, large crabgrass, and purple nutsedge. Treatments included indaziflam at 0, 4, 8, 12, 17, 21, 25, 29, 33, and 37 g ai ha−1 or oxadiazon at 0, 420, 841, 1,260, 1,681, 2,102, 2,354, 2,942, 3,363, and 3,783 g ha−1. Although preemergence herbicides are not used to control perennial weeds, purple nutsedge was included to investigate the effect of selected herbicides on its growth. Herbicide EC50, EC80, and EC90 for seedling emergence inhibition and shoot and root mass reduction were quantified from log-logistic dose–response curves. Herbicide concentration that remains from a preemergence application during the regional species-specific periodicity of emergence was predicted using first-order kinetics equations. Indaziflam and oxadiazon controlled seedling emergence 14 d after treatment (DAT) in the evaluated annual weeds and shoot and root mass in all species 84 DAT. Indaziflam applied in mid-March at 33 g ha−1 may provide up to 90% seedling emergence inhibition in large crabgrass and signalgrass; up to 80% in barnyardgrass; and up to 50% in doveweed. Oxadiazon applied in mid-March at 3,363 g ha−1 may provide up to 80% seedling emergence inhibition in all species. Indaziflam and oxadiazon may control up to 80% shoot mass and up to 50% root mass, respectively, in purple nutsedge and 80% to 90% shoot or root mass in other species. Such information is useful in evaluating adequacy of herbicide management practices for season-long weed control, and it aids turfgrass managers in applying preemergence herbicides at optimal timing based on target weed species.

Weed control in wheat with pyroxasulfone and its combinations with other herbicides

AbstractField and pot investigations were conducted to determine the effectiveness of pyroxasulfone alone and its combinations with other herbicides against diverse weed flora of wheat (Triticum aestivum L.) including multiple herbicide‐resistant (MHR) littleseed canarygrass (Phalaris minor Retz.). Applications of pyroxasulfone 100–127.5 g/ha as pre‐emergence (PE) or early post‐emergence (EPOE) @ 63.75 g/ha at 21–23 days after sowing (1 day before irrigation) were highly effective for control of grass weeds namely P. minor and wild oat (Avena ludoviciana Dur.). It was poor for control of broad‐leaved weeds (Medicago denticulata Willd. and Rumex dentatus L.). However, pyroxasulfone in tank‐mix combination with metsulfuron 4 g/ha, triasulfuron 20 g/ha, and pyroxsulam 18 g/ha effectively controlled (96.5%–99.8%) the diverse weed flora and improved the wheat grain yield (69.5%–285.9%) over untreated weedy control. Also, the pre‐mix of pyroxasulfone + pendimethalin applied as PE was superior to either of these applied alone for weed control and grain yield. Pyroxasulfone 100–127.5 g/ha had yield gain of 119.6%–125.4% and 10.1%–26% over untreated control and pendimethalin 800–1250 g/ha, respectively. In pot studies, straw burnt ash drastically reduced the pyroxasulfone efficacy against P. minor and A. ludoviciana. Pyroxasulfone was also effective in pot studies for control of MHR P. minor having resistance against acetyl‐coA carboxylase (ACCase), acetolactate synthase (ALS), and photosynthesis at the photosystem‐II site‐A (PS‐II) inhibitor herbicides (clodinafop, sulfosulfuron, and isoproturon, respectively). The studies indicate that pyroxasulfone as PE or EPOE can be an alternative grass weed control herbicide in wheat in particular for the control of MHR P. minor.

Preemergence and postemergence weed control in sweet corn on organic soils

AbstractAtrazine and S-metolachlor are the herbicides most relied on by growers to control weeds in sweet corn crops grown in the Everglades Agricultural Area (EAA) in southern Florida. Alternative weed management programs are needed. Field experiments were conducted in 2021 and 2022 to evaluate the efficacy of 1) pyroxasulfone (183 and 237 g ha−1) alone or as a premix with carfentrazone-ethyl (13 and 17 g ha−1) or fluthiacet-methyl (6 and 7 g ha−1), S-metolachlor (1,790 g ha−1) alone or in combination with atrazine (3,360 g ha−1) applied preemergence(PRE); 2) mesotrione (105 g ha−1), topramezone (25 g ha−1), and tembotrione (92 g ha−1) applied postemergence alone or in combination with atrazine (560 and 2,240 g ha−1) or bentazon (1,120 g ha−1); and 3) mechanical cultivation alone at the fourth and the fourth followed by the sixth leaf stages of sweet corn. PRE-applied herbicides did not provide acceptable control of fall panicum, common lambsquarters, or common purslane probably due to a lack of incorporation into the soil because of limited rainfall. POST-applied topramezone alone or in combination with atrazine or bentazon resulted in effective fall panicum control (>91%). Topramezone alone provided 83% and 88% control of common lambsquarters and common purslane, respectively, whereas atrazine added to topramezone resulted in >94% control of both weed species. Mesotrione and tembotrione plus atrazine provided excellent control (>93%) of both broadleaf weed species but poor fall panicum control (<72%). Mechanical cultivation alone did not effectively control any weeds. Overall, treatments that contained topramezone resulted in greater sweet corn yield. These results show that a combination of topramezone, mesotrione, and tembotrione with atrazine resulted in improved broadleaf weed control. Fall panicum control was improved only with the combination of topramezone with atrazine, showing that atrazine is an important mixture component of these herbicides to provide effective POST weed control in sweet corn on organic soils of the EAA.

Study of Effective Promotional Tools for Enhancing the Use of Pre- Emergence Herbicide in Paddy Crop

The article on title “Study of effective Promotional Tools for enhancing the use of Pre-Emergence Herbicide in Paddy Crop” was carried out under the guidance of Dr. NITIN BARKER. Paddy (Oryza sativa) is the major staple food for a large population of world’s population especially in South and East Asia, 65% of the India’s population major staple food is rice. Rice is an important source of food worldwide. However, the growth of weeds in paddy fields pose a major biological threat to higher rice productivity and quality. Weeds have many variable characteristics compared to the crop for examples lack of seed dormancy, uniform growth and high yields. Thus, weeds tend to show larger potential capacity to adapt to stress (e.g., climate change) than crop plants. Consequently, effective management of weed is a vital pre-requisite notable production of rice. For instance, if crop losses of approximately 10–20 % are recovered through effective weed management with the use of appropriate herbicides, there will be additional yield of 0.3–0.6 t/ha. Different weed management practices were studied in paddy in present study were bensulfuron methyl 60 g + 600 g a.i ha-1 as pre emergence followed by mechanical weeding at 30 DAS/T, bispyribac sodium @ 25 g a.i ha-1, farmer’s practice and weedy check. among weed management practices, pre emergence application of bensulfuron methyl + pretilachlor mixture followed by mechanical weeding at 30 DAS/T resulted in higher B:C ratio compared to other methods of weed control. Finally, it could be concluded that there are good opportunities for Herbicide (Stilleto) to create a market space in the study area. The company need to focus on certain factors like farmer’s expectations, field demonstrations and creating awareness in the study area.

Weed Management in Clusterbean under the Application of Different Agrochemicals and Phosphorus Levels

Among the Kharif legumes clusterbean (Cyamopsis tetragonoloba L. Taub) is important crop and popularly known as “Guar” in India. A field experiment was conducted during Kharif 2013 at Agronomy Farm, S.K.N. College of Agriculture, Jobner, Jaipur (Rajasthan) to evaluate the weed management in clusterbean under the application of different agrochemicals and phosphorus levels. The treatments comprising 6 weed control treatments (Weedy check, one hand weeding at 20 DAS, two hand weeding at 20 and 40 DAS, pendimethalin at 0.75 kg/ha, imazethapyr at 100 g/ha and fenoxoprop-p-ethyl at 70 g/ha and four levels of phosphorus (0, 20, 40 and 60 kg/ha) assigned to main and sub plots of spilt plot design, respectively and replicated thrice. Results showed that HW twice at 20 and 40 DAS and pre emergence application of imazethapyr at 100 g/ha resulted significant reduction in weed density and weed dry matter in comparison to most of the treatments. Results further indicated that application of 60 kg P2O5/ha in clusterbean recorded the highest density and dry weight of weeds at all the stages. Maximum weed control efficiency was recorded under two hand weeding at 20 & 40 DAS.

Weed management with Triafamone herbicide in transplanted rice ecosystem

Field experiments were conducted during Rabi 2018-19 (September to January) and Kharif 2019 (May to September). Medium duration rice cv. CO(R) 51 was used as a test variety at Tamil Nadu Agricultural University, Coimbatore, India to study the effect of Triafamone on broad spectrum weed control in transplanted rice. Triafamone was applied at two times. First set of treatments (30, 40,50 and 100 g/ha) applied two to three leaf stage of weeds and second set treatments imposed (30, 40,50 and 100 g/ha) at three days after transplanting of the rice crop. These treatments were compared with Pyrazosulfuron ethy 10% WP @ 15 g/ha, Pretilachlor 5% EC @ 750 g/ha, hand weeding @ 20 and 40 days after transplanting and unweeded control. The major grasses were Echinochloa crus-galli (L.) and E. colonum (L.) while the sedge weed included Cyperus nutans (L.). Among the broad leaved weeds Eclipta alba (L.) and Bergia ammanioides were the dominant species. In both the seasons of the study, lesser population of grass was recorded with the pre and early post emergence application of triafamone herbicide 40 g a.i. ha-1 (1.41 and 1.41 per m-2 at 28 and 42 DAA for both the seasons respectively) and it was closely followed by application of triafamone herbicide 50 g a.i. ha-1 and application of PE Pretilachlor at 0.75 kg a.i. ha-1 and EPOE Pyrazosulfuron ethyl at 15 g a.i. ha-1. The same trend was observed for broad leaved weeds and their weed dry weights. Application of triafamone herbicide at 40 g a.i. ha-1 as pre emergence and early post emergence application recorded highest weed control efficiency of 100, 97.7 and 99.6 % and 97.8% at 42 DAA during both years of experimentation and also resulted in higher grain yield (8052 and 8182 kg ha-1 during rabi 2018-19 and 9018, 9175 kg ha-1 during Kharif 2019). Further, it is noticed that, there was no residual toxicity of herbicide to the succeeding crops. Hence, application of Triafamone 40 g a.i. ha-1 either pre or early post emergence herbicide has higher productivity and no residues in transplanted rice ecosystem.
 Key words: Triafamone, efficacy, weeds and transplanted rice ecosystem

Efficacy of Sulfentrazone 39.6% and Pendimethalin as a Pre Emergence Application against Weed Spectrum of Soybean (Glycine max L. Merrill)

A field experiment was conducted during Kharif season of 2017 at the Research Farm, College of Agriculture, Jabalpur, Madhya Pradesh. The seven treatments comprising of four doses of sulfentrazone (180, 360, 540 and 720 g/ha), application of pendimethalin (750 g/ha) as pre emergence, hand weeding twice at 20 and 40 days after sowing (DAS) including weedy check, were laid out in randomized block design with 3 replications. Results revealed that, Echinochloa colona (28.24%) was the dominant weed species closely followed by Commelina communis (24.42%). However, other monocot weed like Cyperus rotundus (15.56%) and dicots like Phyllanthus niruri (19.34%) and Euphorbia hirta (12.44%) were also found associated with soybean in less numbers. Application of T4- sulfentrazone at 720 g/ha as pre emergence arrested the weed growth remarkably and proved superior to its lower dose (180 g/ha) and application of pendimethalin 750 g/ha. The poor crop-weed competition due to effective control of weeds under this treatment resulted in higher weed control efficiency. Pre-emergence application of T4- sulfentrazone at 720 g/ha recorded maximum grain yield and was at par with other individual herbicides. Similarly, higher net returns and benefit: cost ratio were recorded in T4- sulfentrazone at 720 g/ha fb T3- sulfentrazone at 540 g/ha. It may be inferred from the present investigation that these herbicidal treatments could be used effectively as an alternative for controlling weeds and obtaining optimum seed yield of soybean.

Enlist™ corn tolerance to preemergence and postemergence applications of synthetic auxin and ACCase-inhibiting herbicides

AbstractAllowing the use of two additional modes of action (MOAs), Enlist™ corn is a novelty in the continuum of herbicide-resistant crop development efforts that have occurred since the 1990s. Knowledge of Enlist corn tolerance to labeled herbicides and other herbicides within the same MOA for various use and/or exposure scenarios is not well established. Four site-year field experiments for preemergence (PRE) and postemergence (POST) applications were conducted at sites in Fayetteville (2021 and 2022) and Tillar (2020 and 2021), Arkansas, to evaluate Enlist corn response following PRE or POST applications of synthetic auxin herbicides or those that inhibit acetyl-CoA carboxylase (ACCase). A non-Enlist and an Enlist corn hybrid were used for each herbicide treatment to establish differential tolerance. Injury response to PRE application varied among site-years; clethodim was the only herbicide that occasionally caused significant (7% to 17%) injury to Enlist corn. None of the PRE treatments affected plant height, stand, or yield of Enlist corn; these responses were generally similar or better for Enlist corn compared to non-Enlist corn. Enlist corn showed significant injury to POST applications of florpyrauxifen-benzyl (>10%), fluazifop-P-butyl and quizalofop-P-ethyl (>5%), and clethodim and sethoxydim (>75%) 1 wk after application (WAA). These initial injury responses to clethodim and sethoxydim were generally reflected in Enlist corn yield; however, the minimal injury from fluazifop-P-butyl and quizalofop-P-ethyl did not affect yield. Injury to non-Enlist corn with POST-applied ACCase-inhibiting herbicides 2 WAA was >80%, resulting in a proportionate yield reduction. Even though florpyrauxifen-benzyl caused more initial injury to non-Enlist corn, yield reduction in non-Enlist corn was occasionally less than of Enlist corn, with both hybrids experiencing >75% yield reduction. In summary, Enlist corn may occasionally show transient injury even to labeled herbicides when applied POST, and even though the injury from florpyrauxifen-benzyl is initially mild, it nonetheless results in substantial yield loss.

Herbicide Management of Threespike Goosegrass in California Orchards

Threespike goosegrass (Eleusine tristachya) is a difficult-to-control perennial grass of increasing concern for orchard production systems in the Central Valley of California, USA. This grass has a bunch-type growth habit when tillered, which can interfere with orchard operations, particularly nut pickup from the ground at harvest. From 2016 to 2019, herbicide efficacy on threespike goosegrass was evaluated in a walnut (Juglans regia) orchard in Chico, CA, USA; an almond (Prunus dulcis) orchard in Livingston, CA, USA; and a prune (Prunus domestica) orchard in Orland, CA, USA. At each location, two independent experiments were conducted to evaluate 12 preemergent (PRE) herbicide treatments and eight postemergent (POST) treatments over several years, for a total of 16 trials. PRE herbicides were applied in January according to the region’s typical winter orchard management practices. One treatment included an additional sequential application in March to extend residual activity later into the warm season when threespike goosegrass germinates or resumes growth. In separate studies, POST control of established stands of threespike goosegrass was evaluated in May and June of each year. Each trial was conducted in a randomized complete block design with four replications. Threespike goosegrass control was visually estimated monthly for 5 months after the PRE treatments or at weekly intervals for 5 weeks following POST treatments. The most effective PRE treatment was a sequential application of indaziflam in January, followed by a March application of pendimethalin, providing 90% or greater control of threespike goosegrass 5 months after treatment across all sites and all years. Of the POST treatments, the three graminicides outperformed the other treatments with 73% to 91% control overall sites and years at 5 weeks after treatment. Fluazifop had the highest control ratings (85% to 91%) among the graminicide herbicides but was not always statistically better than clethodim or sethoxydim (74% to 83% control). Glyphosate alone resulted in unacceptable control (33% to 51%) regardless of rates tested, experimental sites, or years. Together, these results confirm grower reports of poor glyphosate performance on threespike goosegrass but suggest that effective herbicide programs can be developed to manage threespike goosegrass using PRE herbicides and POST graminicides registered in California orchard crops.

Assessment of Different Weed Management Practices in Mustard for Enhancement of Productivity

A field experiment was conducted at Krishi Vigyan kendra, Sawaimadhopur, Rajasthan, India in two consecutive years during 2018-19 and 2019-20 on Zone III –B of Rajasthan, India. In this experiment was performed in randomized block design which includes four treatments of weed control i.e. weedy check (T1), Hand weeding at 25 DAS (T2), Hand weeding at 25 & 45 DAS (T3), Pre emergence application of Pendimethaline @ 1.0 kg a.i. ha-1 (T4) and replicated five times. Results revealed that Weed Density (no m-2) 60 days after sowing, Dry weight (kg ha-1) 60 days after sowing, weed control efficiency (%) and weed index found lowest in two hand weeding at 25 and 45 days after sowing fb Pre emergence application of Pendimethaline @ 1.0 kg a.i. ha-1 (T4) during both the years during 2018-19 and 2019-20, respectively. Highest seed yield (2341 kg ha-1) and (2431 kg ha-1) was found under two hand weeding (25 & 45 days after sowing) during 2018-19 and 2019-20 respectively.