Weed Management Options Research Articles

Effect of planting density and weed management options on growth and productivity of Indian mustard

A field experiment was conducted during the winter (rabi) season of 2018–19 and 2019–20 at Kalyani, West Bengal, to study the effect of various planting density and weed-management options on growth and productivity of Indian mustard [Brassica juncea (L.) Czern & Coss.]. The field experiment was conducted in split-plot design with 3 replications, having 30 treatments combinations including 3 planting densities in main-plot, viz. 30 cm × 15 cm, 30 cm × 20 cm and 30 cm × 25 cm; and 10 weed-management options in sub-plots which include pendimethalin @ 1.0 kg a.i./ha, oxadiargyl @ 0.08 kg a.i./ha, pendimethalin @ 1.2 kg a.i./ha, oxadiargyl @ 0.10 kg a.i./ha, pendimethalin @ 1.0 kg a.i./ha + 1 hoeing at 30 days after sowing (DAS), oxadiargyl @ 0.08 kg a.i./ha + one hoeing at 30 DAS, pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS, oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS, weed free and control. Significantly lower weed density and dry-weight of weight observed with 30 cm × 20 and 30 cm × 15 cm plant spacing. Application of oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS and pendimethalin @ 1.20 kg a.i./ha + 1 hoeing at 30 DAS, greatly reduced different species of weeds and their dry weight. With various main-plot treatments, higher seed yield (1,838 kg/ha) of mustard was observed with the 30 cm × 20 cm planting and was statistically better than the other plant spacings. These treatments resulted in higher seed yield to the tune of 8.18 and 12.84% over the 30 cm × 15 cm and 30 cm × 25 cm plant spacings. Weed-free situation, resulted in the highest seed yield (2,230 kg/ha) and showed parity with pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS and oxadiargyl @ 0.08 kg a.i./ha + 1 hoeing at 30 DAS. These treatments registered 93.5, 89.8 and 88.8% more seed yield over the control plots respectively. Economics revealed that, 30 cm × 25 cm plant spacing gave the maximum net returns (`29,280/ha) with benefit: cost ratio of 1.70. The highest net returns (33,850/ha) were observed from the treatment of pendimethalin @ 1.2 kg a.i./ha + 1 hoeing at 30 DAS with a benefit: cost ratio of 1.74. This was closely followed by oxadiargyl @ 0.10 kg a.i./ha + 1 hoeing at 30 DAS.

Impact of weed management practices on weeds and okra crop

A preliminary study was conducted during the summer of 2014 and 2015 at the N.M. College of Agriculture, Navsari Agricultural University, Navsari, Gujarat, India to evaluate the 10 treatments of weed-management, i.e. stale seedbed, pre- and post-emergence herbicides alone and in combination, integrated weed-management and hand-weeding in summer okra [Abelmoschus esculentus (L.) Moench]. Almost 73.2% of weed infestation was dominated by grasses and sedges, followed by broad-leaf weeds (26.8%). Uncontrolled weed growth caused significant reduction in mean green pod yield of okra by 67%. Weed-free plot [3 hand-weedings (HW) at 20, 40 and 60 days after sowing (DAS)] showed the maximum weed-control efficiency (WCE) (88.4%), resulting in higher green pod yield (16.8 t/ha) and net returns (`105,233/ha). Statistically at par yields were also obtained from plots treated with not incorporated and 2 HW at 20 and 40 DAS (14.3 t/ha) and pendimethalin 1.0 kg/ha followed by (fb) quizalofop-ethyl 0.04 kg/ha at 30 DAS (13.9 t/ha) with net returns of `83,442 and `82,277/ha respectively. Application of pendimethalin 1.0 kg/ha (pre) fb quizalofop ethyl 0.04 kg/ha at 30 DAS supressed the weeds effectively (71.3% WCE) which not only reduced the drudgery of farm labour but also found practically more convenient and economically feasible weed-management option for higher production of okra fruit crop.

Energy Dynamics of Rice Production in Eastern India as Influenced by Resource Conserving Establishment Methods and Weed Management

The field experiment was conducted during the wet seasons of 2020 and 2021, at the Agronomy Research Farm of Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India to assess the input energy requirements and output energy production of establishment methods and weed management in rice. The treatments included three establishment methods viz., Dry-direct seeded rice (Dry-DSR), Wet-DSR and puddled transplanted rice (PTR) in main plot and six weed management treatments viz., hand weeding, oxadiargyl @ 90 g ha-1 as pre-emergence (PE) followed by (fb.) penoxsulam+cyhalofop @ 135 g ha-1 as post-emergence (PoE), oxadiargyl @ 90 g ha-1 (PE) fb. triafamone+ethoxysulfuron @ 60 g ha-1 (PoE), oxadiargyl @ 90 g ha-1 (PE) fb. bispyribac sodium @ 25 g ha-1+fenoxaprop @ 56 g ha-1 (PoE), brown manuring (DSR) / green manuring (PTR) fb. 2,4-D at 25 DAS/T and unweeded control in subplot. Dry-DSR utilised 3.2% less input energy than Wet-DSR. PTR recorded highest energy use efficiency (11.88), energy efficiency ratio (5.78), energy productivity (0.393 kg MJ-1) and energy profitability (10.88), followed by Dry-DSR and Wet-DSR. The highest specific energy (4.59 MJ kg-1) was estimated in Dry-DSR, differing significantly with other establishment techniques. Among weed management options, the highest energy use efficiency (11.89) and energy profitability (10.89) was recorded with application of oxadiargyl (PE) fb. penoxsulam+cyhalofop (PoE), being at par with hand weeding, oxadiargyl (PE) fb. bispyribac sodium+fenoxaprop (PoE). Oxadiargyl fb. penoxsulam+cyhalofop under Dry-DSR was highly economic energy efficient, but at par with oxadiargyl fb. bispyribac+fenoxaprop under the same establishment technique.

Efficacy of pre- and post-emergence herbicide combinations on weed control in no-till mechanically transplanted rice

No-till mechanized-transplanted rice was evaluated for different combinations of pre- and post-emergence herbicides to determine feasible, economically viable weed management options to control complex weed flora in rice fields. All pre-emergence herbicides significantly reduced the population of grassy weeds; of these, pendimethalin resulted in the greatest reductions (83%) at 15 days after transplanting (DAT). Among five post-emergence herbicide treatments, the combination of bispyribac-sodium (10%SP) + pyrazosulfuron (10%WP) was found to be the most effective in controlling all weed flora at both 35 and 55 DAT. The sequential application of pendimethalin (pre-emergence) followed bispyribac-sodium + pyrazosulfuron (post-emergence) resulted in significantly higher rice grain yield (4.4 t-ha−1) and relative gross-margin (417 USD-ha−1) than all other treatments. A strong negative correlation was observed between rice grain yield and weed biomass, and a strong positive correlation between rice grain yield and weed control efficiency. Our findings demonstrate the potential to combine pre- and post-emergence herbicides in no-till mechanized-transplanted rice; these findings have applications globally in regions where rice is established by no-till or mechanized transplanting.

The impacts of ecological mowing combined with conventional mechanical or herbicide management on weeds in orange orchards

AbstractIn fruit crops like citrus, weeds coexist throughout their long cycle and can cause several yield losses. Ecological mowing (ECO) is an integrated weed management (IWM) option for citrus, as it produces an in‐situ mulch that suppresses the weeds; however, there is a lack of information on the impacts of tree‐row conventional (CONV) and ECO mechanical weed control when combined with residual or non‐residual herbicides, or standard frequent mechanical (MECH) control. This study aimed to evaluate, for 3 years in a young orange orchard, IWM using ECO and conventional mowing when combined with one of five weed control programmes: pre‐emergent (PRE) herbicides (sulfentrazone [spring], indaziflam [summer]), post‐emergence (POST) herbicides (glyphosate [spring], saflufenacil [summer]), PRE + POST herbicides (sulfentrazone + glyphosate [spring], indaziflam + saflufenacil [summer]) and P/P (pre/post‐emergence duality) herbicides (flumioxazin [spring], diuron [summer]). Impacts on cover crop biomass deposition, weed density, population dynamics, biomass accumulation and seed banks were evaluated. Alternanthera tenella Colla (joyweed), Bidens pilosa L. (hairy beggarticks), Digitaria horizontalis Willd (crabgrass), Galinsoga parviflora Cav. (smallflower galinsoga) and Raphanus raphanistrum L. (wild radish) were the most critical weeds with changes in their population dynamics over time. The ECO treatment promoted greater biomass deposition in the tree‐rows (up to ≈8.0 t ha−1), reducing weed density and biomass accumulation by mulch formation; similarly, MECH resulted in low weed density and a reduction in biomass accumulation. The POST and P/P treatments resulted in low levels of weed control, while ECO + PRE + POST led to almost absolute weed control (>95%). Thus, we suggest ECO + PRE + POST is an efficient IWM option in citrus tree‐row crops with low‐risk herbicide resistance (up to 5 MoA year−1 + mulch).

Bio‐efficacy of different post‐emergence herbicides in mungbean

AbstractWeeds result in a significant yield loss in mungbean (Vigna radiata[L.] R. Wilczek). However, post‐emergence (POST) herbicides are limited in mungbean for broad‐spectrum weed control. Therefore, we evaluated the efficacies of different herbicides in mungbean to find a suitable broad‐spectrum POST herbicide. Nine herbicides, weed‐free check, and unweeded control treatments were tested in a randomised block design with three replications for two consecutive years. Among the tested herbicides, clodinafop‐propargyl + sodium‐acifluorfen 122.5 g a.i. ha−1applied at 15 days after sowing (DAS) reduced the broad‐leaved weed dry weight at 35 DAS and harvest by 55.8% and by 58.6% (p < 0.05) compared with the unweeded control respectively. Notably, it minimised the total weed dry weight by 23.1%–30.3% compared with the recommended herbicide pendimethalin 1 kg a.i. ha−1– quizalopfop‐p‐ethyl 100 g a.i. ha−1(p ≤ 0.05). Clodinafop‐propargyl + sodium‐acifluorfen had higher weed control index (58.2% at 35 DAS and 62.1% at harvest) over the remaining tested herbicides. Unweeded controls resulted in 51% yield loss compared with the clodinafop‐propargyl + sodium‐acifluorfen that did not differ from pendimethalin − quizalofop‐p‐ethyl for seed yield of mungbean. Decreasing order of treatment efficacy on mean grain yield across two years comprised the weed‐free check, clodinafop‐propargyl + sodium‐acifluorfen and pendimethalin − quiza‐lofop‐p‐ethyl, imazethapyr + imazamox, tembotrione, and topramezone. [Correction added on 10 November 2022, after first online publication: In the preceding sentence, changes have been made to the article content to improve clarity in this version.] Application of clodinafop‐propargyl + sodium‐acifluorfen led to the greatest increase in soil microbial biomass carbon, indicating higher levels of soil biological and rhizospheric activity. We suggest that clodinafop‐propargyl + sodium acifluorfen is a suitable broad‐spectrum option for weed management of mungbean.

Integrated Use of Herbicides and Mulching for Sustainable Control of Purple Nutsedge (Cyperus rotundus) in a Tomato Crop

Purple nutsedge (Cyperus rotundus L.) is a problematic weed in tomato (Lycopersicon esculentum L.) crops causing significant yield losses. Although several chemical options are available for this weed, the level of control is often unsatisfactory, and the consistent use of herbicides has a risk of resistance evolution. Therefore, we evaluated the efficacy of two herbicide options, halosulfuron and fomesafen + S-metolachlor, alone or integrated with natural and plastic mulches in controlling purple nutsedge in tomato crops in a three-year field study. The use of herbicides or mulches alone did not provide effective weed control (below 65%). However, the combination of natural mulch and fomesafen + S-metolachlor provided the most effective weed control by reducing the density and biomass of purple nutsedge by up to 83% and 81%, respectively, as compared with the season-long untreated control. The use of a natural mulch in combination with the herbicides halosulfuron or fomesafen + S-metolachlor also resulted in the highest tomato yield (ca. 3.3 kg per plant). This integrated treatment improved tomato yield by over 400% as compared with the season-long untreated control. The integrated use of a plastic mulch and two chemical options resulted in a 67–74% weed biomass reduction and a 332–368% yield increase over the season-long untreated control. These findings suggest that the combinations of herbicides and mulches are effective integrated weed management options for purple nutsedge in tomato crops.

Weed growth, nutrient removal and yield of direct-seeded rice as influenced by establishment methods and chemical-cum-mechanical weed management practices

Direct seeding of rice (Oryza sativa L.) has since long been viewed as a potential alternative to unsustainable water-intensive transplanted rice (TPR) world-over, but heavy infestation of a variety of weed species limits the large-scale adoption of direct-seeded rice (DSR) cultivation. Hence, a 2-year field investigation was carried-out in a spilt-plot design, at Banaras Hindu University, Varanasi, during rainy seasons of 2016 and 2017 to assess the influence of various crop establishment methods (CEMs) and weed management options (WMs) on diverse weed-flora, nutrient removal by weeds, weed-control efficiency (WCE) and yield of DSR (cv. Rajendra Kasturi). The results revealed that zero-till DSR + residue + Sesbania brown manure (ZTDSR + R + SBM) was most effective in containing crop-weed competition, lowered density of Echinochloa colona (L.) Link, Echinochloa crusgalli (L.) Beauv., Cynodon dactylon (L.) Pers., Eclipta alba (L.) Hassak., Caesulia axillaris Roxb., Cyperus rotundus L., Cyperus iria L., Fimbristylis miliacea (L.) Vahl. by 63.4% and enhanced grain yield by 22.8%. Further, applying pendimethalin at 1000 g ai ha−1 as PRE. and later post-emergence (POST) spray of chlorimuron + metsulfuron at 4 g ai ha−1 each 20 days after sowing (DAS) supplemented with 1 hand-weeding (HW) 45 DAS was found to be a better weed management option as this treatment recorded the lowest density and nutrient depletion by above mentioned weeds and higher WCE, thereby improving rice yield by 3–19.5% over other studied WMs. Also, the combination of this weed management option with ZTDSR + R + SBM suppressed weeds to a greater extent, restricting weeds to deplete nutrients (N, P and K) from the soil and finally fetched the highest DSR yield.

Field Bindweed (Convolvulus arvensis) Control in Tef (Eragrostis tef (Zucc.) Trotter) through Various Herbicide Combinations

Field bindweed is the major weed problem for tef producers across the central highlands of Ethiopia. Herbicide application alone or coupled with once or twice hand weeding for field bindweed control is difficult due to its biological features, labor-intensive, and time-consuming. The field trial was carried out at Debre Zeit from 2020 to 2021 cropping seasons to investigate different postemergence herbicides against the grass and broadleaf weeds, in general, and field bindweed in particular, in tef farming, using a randomized complete block design with three replications. As a result, we could see that the herbicide combination had no visible effect on durum wheat’s overall performance, which makes us recommend it for the control of field bindweed. In the sequential application, a wide spectrum of herbicides (Musket Power OD 460, Pallas 45 OD, and Sekator OD 375) were applied at tillering stage, and other selective herbicides (Derby 175 SC and 2,4-diamine salt 720 g/L 720 g/L) were applied at the heading stage, and the last nonselective herbicide (Roundup) was applied at physiological maturity of tef when the Convolvulus arvensis was regrowth naturally/latecomer weed. All postemergency herbicide treatments reduced significantly both broadleaf and grass weeds, in general, and C. arvensis infestation, in particular, when compared to the weedy control. Of these, Musket Power OD 460 at tillering stage integrated with 2,4-diamine salt 720 g/L at the heading stage was more effective than other herbicides for eliminating all weeds and C. arvensis in particular throughout the crop life. This weed management option resulted in considerably enhanced weed control efficiency and weed killing potential, reduced weed dry biomass and yield loss, improved grain yield, and economic benefit with an acceptable marginal rate of return for tef growers.

Seed viability of feathertop Rhodes grass (Chloris virgata Sw.) reduced by silage, digestion, and sheep rumen digestion

Weed seeds can be spread by different vectors, and seed dispersal is an important mechanism for the weed to persist. Weed seeds passaging through the digestive tract of a ruminant animal is expected to result in reduced viability. Two separate experiments were conducted to determine the germinability and viability of the mature seeds of feathertop Rhodes grass (Chloris virgata Sw.) after exposure to four treatments, that is, 3 months in silage, 48 h in the rumen of steers, silage plus digestion, and passing through the digestive tract of sheep. Our results showed that three different treatments (silage, digestion, and silage plus digestion) can inhibit 90%–100% of the seed germination of feathertop Rhodes grass. Both silage and digestion reduced seed viability by 65%–90%, depending on the population. Silage followed by digestion reduced viability by 80%–97%. The sheep feeding study showed that total viable seeds from the daily recovery of feces for 12 consecutive days after ingestion was only 0.084% and 0.022% in the 2020 and 2021 experiments, respectively. In comparison with the untreated control, the seed viability of feathertop Rhodes grass was reduced by more than 99.9% after feeding through sheep, indicating that the spreading of feathertop Rhodes grass seeds via sheep feces is minimal. These results indicate that silage, digestion, silage followed by digestion, and the ingestion of mature seeds are effective non-chemical weed management options for an integrated weed management package for feathertop Rhodes grass.

Field-Evolved ΔG210-ppo2 from Palmer Amaranth Confers Pre-emergence Tolerance to PPO-Inhibitors in Rice and Arabidopsis.

Resistance to protoporphyrinogen IX oxidase (PPO)-inhibitors in Amaranthus palmeri and Amaranthus tuberculatus is mainly contributed by mutations in the PPO enzyme, which renders herbicide molecules ineffective. The deletion of glycine210 (ΔG210) is the most predominant PPO mutation. ΔG210-ppo2 is overexpressed in rice (Oryza sativa c. ‘Nipponbare’) and Arabidopsis thaliana (Col-0). A foliar assay was conducted on transgenic T1 rice plants with 2× dose of fomesafen (780 g ha−1), showing less injury than the non-transgenic (WT) plants. A soil-based assay conducted with T2 rice seeds confirmed tolerance to fomesafen applied pre-emergence. In agar medium, root growth of WT rice seedlings was inhibited >90% at 5 µM fomesafen, while root growth of T2 seedlings was inhibited by 50% at 45 µM fomesafen. The presence and expression of the transgene were confirmed in the T2 rice survivors of soil-applied fomesafen. A soil-based assay was also conducted with transgenic A. thaliana expressing ΔG210-ppo2 which confirmed tolerance to the pre-emergence application of fomesafen and saflufenacil. The expression of A. palmeri ΔG210-ppo2 successfully conferred tolerance to soil-applied fomesafen in rice and Arabidopsis. This mutant also confers cross-tolerance to saflufenacil in Arabidopsis. This trait could be introduced into high-value crops that lack chemical options for weed management.

Herbicide Options for Suitable Weed Management of Transplanted rice in North-Eastern Ghat Zone of Odisha

A field study aimed to assess different weed management tactics in transplanted rice was demonstrated during rainy season in four villages of Ganjam district of Odisha under farmer participatory mode for two years (2019 and 2020). From the concluded research work, it was observed that application of pretilachlor (0.75 kg/ha) within 3 DAT followed by bispyribac sodium @ 25kg/ha at 25 DAT recorded the highest WCE (73.27%), grain (4186 and 4351 kg/ha) and straw yield (5349 and 5308 kg/ha). Hand weeding performed better with respect to WCE (80.1, 81.3 % at harvest) but net return (Rs. 37073 /ha, Rs. 38119 /ha) was found to be low. While Pretilachlor (0.75 kg/ha) within 3 DAT followed by bispyribac sodium (25 kg/ha) at 25 DAT recorded the highest net return (Rs. 41798/ha, Rs. 43956 /ha) and B:C ratio (1.87, 1.89) than other treatments.

Studies on Relative Economics of Apple Nursery Production under Different Weed Management Practices in Kashmir Valley, India

Aims: The purpose of this study was to assess the relative economics of various weed management practices in apple nursery in Kashmir valley, India.
 Study Design: A Randomized Complete Block Design with seven treatments and three replications was employed as the experimental design.
 Place and Duration of Study: The experiment was laid out at the Experimental Farm, Division of Fruit Science, Faculty of Horticulture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, Shalimar Campus, Srinagar, Jammu and Kashmir, India during the year 2020.
 Methodology: Seven weed management treatments (manual weeding, pendimethalin @ 1 kg a.i. ha-1, pendimethalin @ 1 kg a.i. ha-1 + manual weeding, paddy straw mulch-6 cm thick, black polyethylene mulch-200 micron), weed-free and weedy check) were tested in apple nursery (cv. Silver Spur grafted on M9-T337). The input costs and output in terms of monetary values were calculated under different treatments at prevailing market rates. The net return and benefit-cost (B:C) ratio was worked out based on input and output values under each treatment.
 Results: The treatment paddy straw mulch showed the highest input cost (₹9543725.90) while black polyethylene mulch resulted the maximum output (17113252.80). The maximum net returns of ₹78,02,726 from grafted apple nursery plants were recorded under black polyethylene mulch with a benefit-cost ratio of 1.83 followed by pendimethalin @ 1 kg a.i. ha-1 + manual weeding with net returns of ₹71,60,541 and benefit-cost ratio of 1.77.
 Conclusion: Black polyethylene mulch resulted highest net return and B:C ratio, hence it found to be most profitable weed management practice in apple nursery. Pendimethalin @ 1 kg a.i. ha-1 + manual weeding can also be considered as alternative weed management option.

Conservation Agriculture- Based Planting Techniques and Weed Management Practices Influence on Nutrient Content and Their Uptake in Dry Direct-Seeded Rice (Oryza sativa L.)

Conventionally established rice leads to major challenges in crop production like soil health degradation, water table declination and labour scarcity which ultimately increases the cost of production. To address these issues of transplanted rice, different conservation agriculture (CA) based crop establishment practices in combination with suitable weed management options were incorporated to sustain rice productivity. The field trial was conducted for two years during kharif season of 2018 and 2019 at Research Farm, Banaras Hindu University, Varanasi, Uttar Pradesh (India). The experiment was laid out in split plot design having four planting techniques in main plots viz., farmer’s practice (Conventional Transplanting), zero-till direct seeded rice (ZT-DSR), reduced-till direct seeded rice (RT-DSR) (Rotavator single pass) and conventional-till direct seeded rice (CT-DSR) and five weed management practices viz., pendimethalin 1 kg ha-1 pre-emergence (PE) followed by (fb) chlorimuron + metsulfuron (4g + 4g ha-1) at 20 days after sowing (DAS), pendimethalin 1 kg ha-1 PE fb pyrazosulfuron (30 g ha-1) at 20 DAS, bispyribac-sodium + chlorimuron + metsulfuron (25g + 4g + 4g ha-1) at 20 DAS, hand weeding at 20 and 40 DAS and Weedy check in sub-plots and replicated thrice. The results showed that Nitrogen (N), Phosphorus (P) and Potassium (K) content in grain and straw were not significantly influenced by planting techniques and weed management practices. However, among various crop establishment methods CT-DSR recorded significantly higher N, P and K uptake by both grain and straw over rest of the treatments except ZT-DSR during both the years. Similarly, two hands weeding (at 20 DAS and 40 DAS) recorded the highest N, P and K uptake by the crop. With respect to herbicidal treatments, higher N, P and K uptake by crop was found with the application of pendimethalin 1 kg ha-1 (pre-em) fb chlorimuron + metsulfuron (4g + 4g ha-1) at 20 DAS compared to others during both the years of experimentation. Based on the results, it is concluded that application of pendimethalin 1 kg ha-1 PE fb chlorimuron + metsulfuron (4g + 4g ha-1) at 20 DAS to CT-DSR was registered maximum N, P and K uptake by both grain and straw of rice.

Nutrient Availability and Nutrient Uptake by Crop and Weed as Influenced by Stale Seedbed, Mulching and Mechanical Weeding in Okra

Background: Weeds are the major biological constraint in okra due to its slow initial growth and wider row spacing. Due to severe crop weed competition, weeds removed considerable amount of nutrients from the soil. Competition exists between the crop and weed for nutrients results in nutrient deficiencies in crop. Hence the present experiment is formulated to assess the effect of stale seedbed, mulching and mechanical weeding on nutrient availability, nutrient uptake by crop and weed in okra. Methods: Experiment was conducted at Coconut Research Station, Balaramapuram, Thiruvananthapuram, Kerala during Rabi 2020-21. Design adopted for the study was RBD with two factors. The first factor was seedbed preparation (S) and the second factor was weed management (W). Stale seedbed (S1) and normal seedbed (S2) were the two different seedbed preparation methods and dried banana leaf mulch @10 t ha-1 alone (W1), dried banana leaf mulch @10 t ha-1 fb wheel hoe weeding at 30 and 45 DAS (W2), dried banana leaf mulch @10 t ha-1 fb hand weeding at 30 and 45 DAS (W3), wheel hoe weeding at 15, 30 and 45 DAS (W4), hand weeding at 15, 30 and 45 DAS (W5) and weedy check (W6) were the six different weed management options tried. Soil samples were collected after the harvest of the crop to determine the nutrient availability. Weed samples at 30 and 60 DAS and plant samples at harvest were analyzed to determine the NPK content and respective uptake of nutrients were calculated by multiplying the nutrient content with DMP. Result: Stale seedbed significantly enhanced the dry matter production and nutrient uptake by okra at harvest and lowered the nutrient removal by weeds at 30 and 60 DAS. Compared to non-stale, stale seedbed recorded significantly higher fruit yield. Among the weed management, wheel hoe weeding at 15, 30 and 45 DAS, recorded the lowest total weed dry weight at 30 and 60 DAS and resulted in the highest NPK uptake by crop and fruit yield. Uncontrolled weed growth resulted in a loss of 81.33, 18.16 and 50.84 kg N:P:K ha-1 at 30 DAS and 102.09, 57.90 and 55.31 kg N:P:K ha-1 at 60 DAS, respectively. Nutrient removal by weeds was the lowest in wheel hoe weeding at 15, 30 and 45 DAS and the highest in weedy check. It could be concluded that, wheel hoe weeding at 15, 30 and 45 DAS was the best option for the management of weeds, higher nutrient availability and uptake and yield in okra.

Compatible agri-horti systems and weed management options for Mungbean production

For increasing the production of mungbean, a field experiment was conducted in split plot design, to evaluate the compatible agri-horti system and efficient weed management practice. Keeping three agrihorti systems [guava, custard apple and open field] in the main-plots and six weed management practices [pendimethalin 1000 g a.i./ha (PE), imazethapyr 125 and 200 g a.i./ha (PoE), 1- HW (20 DAS), 2-HW (15 & 30 DAS) and weedy check] in sub-plots. Age of agri-horti plantation was 5-years old. Custard apple agrihorti system and open field recorded highest and lowest infestation of weeds, respectively. However, most of the growth, yield attributes and yield did not vary with agri-horti systems. 2-HW recorded the lowest infestation of weeds vis-Ã -vis maximum growth of mungbean. Application of imazethapyr 200 g a.i./ha recorded the lowest growth of predominant weed species, however, dry matter accumulation, yield attributes and yield of mungbean were comparable with imazethapyr 125 g a.i./ha.

Weed management and tillage effect on rainfed maize production in three agro‐ecologies in Mexico

AbstractMaize (Zea mays L.) is grown in a wide range of agro‐ecological environments and production systems across Mexico. Weeds are a major constraint on maize grain yield, but knowledge regarding the best weed management methods is lacking. In many production systems, reducing tillage could lessen land degradation and production costs, but changes in tillage might require changes in weed management. This study evaluated weed dynamics and rainfed maize yield under five weed management treatments (pre‐emergence herbicide, post‐emergence herbicide, pre‐emergence + post‐emergence herbicide, manual weed control, and no control) and three tillage methods (conventional, minimum and zero tillage) in three agro‐ecologically distinct regions of the state of Oaxaca, Mexico, in 2016 and 2017. In the temperate Mixteca region, weeds reduced maize grain yields by as much as 92% and the long‐growing season required post‐emergence weed control, which gave significantly higher yields. In the hot, humid Papaloapan region, weeds reduced maize yields up to 63% and pre‐emergence weed control resulted in significantly higher yields than treatments with post‐emergence control only. In the semi‐arid Valles Centrales region, weeds reduced maize yields by as much as 65%, but weed management was not always effective in increasing maize yield or net profitability. The most effective weed management treatments tended to be similar for the three tillage systems at each site, although weed pressure and the potential yield reduction by weeds tended to be higher under zero tillage than minimum or conventional tillage. No single best option for weed management was found across sites or tillage systems. More research, in which non‐chemical methods should not be overlooked, is thus needed to determine the most effective weed management methods for the diverse maize production systems across Mexico.

The Impact of Different Weed Management Systems on Weed Flora and Dry Biomass Production of Barley Grown under Various Barley-Based Cropping Systems.

Weeds are among the major issues responsible for reduction in yield and profit in any crop production system. Herbicides are the easiest and quickest solution of weeds; however, their frequent use exert negative consequences on environment, human health, and results in the evolution of herbicide-resistant weed species. Due to these reasons, alternative weed management methods that are less harmful to environment and human health are needed. This two-year study evaluated the impact of different weed management options, i.e., false seedbed (FS), allelopathic water extracts (AWE), chemical control (CC), weed-free (WF) weedy-check (WC) on weed spectrum in various barley-based cropping systems, i.e., fallow-barley (FB), maize-barley (MB), cotton-barley (CB), mungbean-barley (M*B), and sorghum-barley (SB). Data relating to density, diversity, and biomass production of weed species prevailing in the studied cropping systems were recorded. Interactive effect of weed management methods and barley-based cropping systems significantly altered weed diversity, and densities of individual, broadleaved, and grassy weeds. A total 13 weed species (ten broadleaved and three grass) were recorded during both years of study. The highest dry biomass, diversity, and density of individual, broadleaved, and grassy weeds were noted in WC treatment, whereas WF treatment resulted in the lowest values of these traits. Chemical control resulted in the highest suppression of weed flora and improved dry biomass production of barley followed by AWE. The SB cropping system with CC or AWE resulted in the least weed flora. The M*B cropping system with CC or AWE produced the highest dry biomass of barley. It is concluded that including sorghum crop in rotation and applying AWE could suppress weeds comparable to herbicides. Similarly, including mungbean in rotation and applying AWE could increase dry biomass production of barley. In conclusion, herbicides can be replaced with an eco-friendly approach, i.e., allelopathy and inclusion of sorghum crop could be helpful in suppressing weed flora.

Productivity of Groundnut + Pigeonpea Relay Intercropping System as Influenced by Weed Management Options

Background: Weed management is one of the most important agronomic constraints leading to severe losses in the cropping system. Intercropping has several advantages to mitigate the losses faced by monocropping in addition to which if there is a proper control of weeds then the advantages of the intercropping system can be multiplied. Methods: An investigation was conducted on medium black clayey soils at Junagadh during kharif 2019-20 and 2020-21 in randomized block design with 10 treatments replicated thrice, to evaluate the effect of different weed management options on the growth and yield of groundnut + pigeonpea relay intercropping. The treatments were: pendimethalin 0.9 kg ha-1 as PE fb interculture and hand weeding at 45 DAS (T1), pendimethalin 0.45 kg ha-1 + oxyfluorfen 0.09 kg ha-1 as PE fb interculture and hand weeding at 45 DAS (T2), interculture and hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE (T3), interculture and hand weeding at 15 DAS fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE (T4), interculture and hand weeding at 15 DAS fb propaquizafop 70 g ha-1 at 45 DAS as POE (T5), pendimethalin 0.9 kg ha-1 as PE fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as POE (T6), pendimethalin 0.9 kg ha-1 as a PE fb quizalofop p ethyl 40 g ha-1 at 45 DAS as POE (T7), pendimethalin 0.9 kg as ha-1 PE fb propaquizafop 70 g ha-1 at 45 DAS as POE (T8), weed free (T9) and unweeded control (T10). Result: The results of the experiment revealed that weed free registered significantly higher plant height, number of branches, dry matter per plant and number of root nodules per plant in groundnut and pigeonpea and was statistically on par with to intercultureand hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE, pendimethalin 0.9 kg ha-1 as PE fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (ready mix) 1 kg ha-1 at 45 DAS as PoE. The data on yield attributes and yield of both the crops depicted that significantly superior results were obtained with weed free treatment, which was statistically at par with intercultureand hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (Ready mix) 1 kg ha-1 at 45 DAS as PoE and pendimethalin 0.9 kg ha-1 as PE fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (Ready mix) 1 kg ha-1 at 45 DAS as PoE. While in case of groundnut equivalent pod and haulm yields, statistically superior yields were registered with weed free treatment, which was statistically at par with intercultureand hand weeding at 15 DAS fb sodium acifluorfen 16.5% + clodinafop propargyl 8% (Ready mix) 1 kg ha-1 at 45 DAS as PoE.

The role of weed seed contamination in grain commodities as propagule pressure

The international grain trade is a major pathway for the introduction of alien plants because grain commodities can be contaminated with various weed seeds. To evaluate how alien weed seeds derived from imported grain commodities affect the local flora in international trading ports, we conducted a floristic survey at each of the 10 grain landing ports and non-grain landing ports throughout Japan to compare the flora between these two types of ports. We also surveyed weed seed contamination of wheat imported into Japan, and the contamination rate was calculated for each species based on our survey and previous studies on weed seed contamination. The flora clearly differed between the grain landing ports and the non-grain ports. In the grain landing ports, alien species were more abundant than in non-grain landing ports. There was a tendency for the more abundant species at the grain landing ports to show higher contamination levels in grain commodities. These results indicate that contaminant seeds spill from imported grain in grain landing ports and the most common contaminant species are likely to become established. We clearly show that weed seed contamination in grain commodities plays an important role in propagule pressure. Gathering information about the prevalence of weeds in grain-exporting countries and monitoring the weed species composition in imported grain commodities is becoming increasingly important for predicting the unintentional introduction of troublesome weeds and identifying effective weed management options.