Weed Management Regimes Research Articles

Sweet corn genotypes and ear insect infestations cultivated under different weed management regimes

Sweet corn genotypes and ear insect infestations cultivated under different weed management regimes

Agronomic assessment of the yield variability and yield gap of maize in Bhutan

Maize is the staple food crop in Bhutan, which has not achieved national food self-sufficiency. On-farm assessment of yield variability would provide insights into the priorities for Bhutan's maize development program. Here, we conducted three studies in Bhutan: a household survey, on-station experiment, and on-farm monitoring. First, we interviewed 100 households and collected information on maize crop management options and farming characteristics. Second, we evaluated maize growth at two research stations in different elevation zones (640 and 1,700 ​m a.s.l.). Third, we harvested maize from 25 farm fields at low and high elevations. The gaps between potential yield (with the best management practices at the research stations) and average farm yield and between the best and average farm yields were 53% and 23%, respectively, at the low elevation, and 23% and 20%, respectively, at the high elevation. The classification and regression tree (CART) model showed that field location (distance from the farmer's home), seed source (certified vs. self-produced), and the number of household members involved in farming were the key farming characteristics that affected yield variability, and the manure application regime, urea application, sowing method, and weeding frequency were key management practices. Our results suggest that future research should clarify the most suitable sowing methods and nutrient and weed management regimes, and identify optimal cultivars for each elevation zone, with the goal of developing crop management guidelines for smallholder farmers in Bhutan.

Weed Community Composition in Simple and More Diverse Cropping Systems

Weed communities in three cropping systems suitable for the Midwestern USA were studied from 2017 to 2020 to examine how crop diversification and the intensity of herbicide use affected weed community diversity, stand density, and aboveground mass. A baseline 2-year cropping system with corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) grown in alternate years was diversified with cool-season crops, namely oat (Avena sativa L.), red clover (Trifolium pratense L.), and alfalfa (Medicago sativa L.) in 3-and 4-year systems. Herbicide was not applied in the cool-season crops. Changing weed management regime from broadcast to banded application and interrow cultivation in corn and omitting herbicide in cool-season crops of the 3- and 4-year rotations resulted in an overall reduction of herbicide a.i mass. The reduction in the mass of herbicide active ingredients was associated with increases in weed stand density, aboveground mass, and community diversity. Increased weed abundance under herbicide mass reduction was not associated with crop yield loss. In the cool-season crops phases of the 3- and 4-year rotations, weed emergence was increased but weed growth was not, as compared with the warm-season crop environments. The dominance of aggressive weed species such as common waterhemp (Amaranthus tuberculatus (Moq ex DC) J.D. Sauer) and common lambsquarter (Chenopodium album L.) tended to be greater in corn and soybean phases of the rotations than in oat, red clover, and alfalfa.

Redesigning traditional weed management practices in faba bean fields to optimize food‐feed production in the smallholder system

AbstractDuringthe main cropping season, Ethiopian farmers deliberately weed faba bean (Vicia faba L.) fields much later than recommended and use the weed herbage mass as feed. This study examined the rationale behind farmers’ practices and explored options to further improve productivity. The study involved two experiments. The first compared the overall benefit from the traditional weed management regime against the frequent weeding recommendation. Sixty farmers participated, each preparing two plots. The plots were randomly assigned to either traditional (one late weeding) or improved (two early weeding) management. The second examined the suitability of intercropping faba bean with oat (Avena sativa L.). It involved a 5 × 3 factorial experiment, three management practices (traditional, improved, and faba bean oat intercropping) and five faba bean varieties repeated over 3 yr. In the first experiment the improved weed management increased grain yield (2.49 vs. 2.12 Mg ha–1) compared to the traditional. But the traditional management produced higher (P < .01) weed forage biomass (2.12 vs. 0.27 Mg ha–1) compared to the improved. The analysis showed the opportunity costs associated with the loss in weed forage biomass were not convincingly offset by the economic gains from increased grain yields. In the second experiment, grain yield was again highest for the improved weed management and lowest for the intercropping. Analysis of economic returns revealed that the intercropping management provides greater benefit over the traditional management practice. Farmers’ decisions have a rational economic basis and building on the traditional practicewith improved forage intercropping would allow to further optimize productivity.

Weed prevalence and productivity of transplanted rice influences by varieties, weed management regimes and row spacing

ABSTRACT In input intensive agriculture, weeds are major biotic constraints which are likely to increase and become more complex. Overreliance on single weed management practice may further exaggerate weed severity and also invite adverse effect, therefore, urgent technological intervention adopted on eco-friendly integrated weed management to improve weed control and sustaining the productivity in transplanted rice. The aim of the study was to compare two popular rice varieties (‘Swarna’ and ‘Mahamaya’) with two row spacing (15 and 20 cm) along with three weed management regimes [weedy, bispyribac sodium 25 g ha-1 and two hand weeding at 20 and 40 days after transplanting (DAT)] on weed suppression and rice productivity. Our findings suggest that Swarna at 15 cm spacing along with two hand weeding enhance the weed suppression and provides higher rice productivity and can be adopted as integrated weed management options to minimize yield loss due to weeds competition in the region. In the study, more than two factors of weed management have been attempted which provide additional information to researcher, policy makers and rice growers to choose and disseminate real integration of weed management options.

Reduction in weed infestation through integrated depletion of the weed seed bank in a rice-wheat cropping system

Chemical-dependent weed control has led to the evolution of herbicide-resistant weeds and pollution of arable land and water systems, posing a great threat to food security and environmental safety. For the first time, we developed a simple weed management regime to ecologically deplete the weed seed bank under a wheat-rice cropping system, which in turn allowed a reduction in the frequency of conventional herbicide applications while sustainably reducing weed infestation levels. The key ecological methods adopted here involve cleaning irrigation water by intercepting seeds at the water entrance and exit and removing floating weed seeds with a net during irrigation before rice planting, which significantly reduced the input of weed seeds into the seed bank. Quantitative analysis of the weed seed bank and population dynamics showed that implementation of this management regime consecutively for 6 years reduced the density of the total weed seed bank by 51% and the dominant grassy weed population density by 53% compared to those at the beginning. The effect of this ecologically sound weed control regime was comparable to that of conventional dual- or triple-application herbicide chemical control in each crop growing season. The results indicated that, compared with the conventional control method, the integrated weed management method could reduce the number of herbicide applications by half and reduce costs and labor by 30%. Furthermore, quantitative modeling analysis of the seed bank and population dynamics of the dominant weed species, Alopecurus japonicus, showed that continuous adoption of this ecological strategy could deplete the seed bank by more than 90%, thereby freeing the fields of the presence of this noxious weed.

Effect of Inorganic Fertilizer Micro-dosing and Weed Management Regimes on Finger Millet Productivity in Uganda

Finger millet yields in farmers’ fields are low primarily due to low soil fertility and poor weed management. Fertilizer application could be one of the key strategies used to address the problem. However, due to high cost of fertilizer, its utilization has been limited to very few farmers in the country. Consequently, a study was conducted in Kuju sub-county, Amuria district in Eastern Uganda during 2016 long and short rains to determine the effect of micro dosing and weeding time on finger millet performance and weed growth. The experiment was laid out in a randomized complete block design in a split plot treatment structure. Weeding times constituted the main plot [weeding at 20 DAS (days after sowing), 30 DAS, 45 DAS, and 20 & 45 DAS (double weeding)], while fertilizer rates (N 16.6 kg ha-1 + P2O5 10.6 kg ha-1; P2O5 10.6 kg ha-1; N 16.6 kg ha-1; N0 + P0, and N 83 kg ha-1 + P2O5 52 kg ha-1) constituted the sub plots. Results of this study revealed that the interaction between weeding at 45 DAS and fertilizer micro-dosing significantly (P < 0.05) reduced weed biomass (7.7 × 10-4 kg ha-1) without significant increase in finger-millet grain yield. Interaction of fertilizer micro-dosing (N 16.6 kg ha-1 + P2O5 10.6 kg ha-1) with weeding once at 20 DAS recorded the highest (2292 kg ha-1) finger millet grain yield with significant (P < 0.05) reduction in days to finger millet flowering. Therefore, it is recommended that fertilizer micro-dosing at N 16.6 kg ha-1 + P2O5 10.6 kg ha-1 and weeding once at 20 DAS can be used to control weeds and enhance finger-millet productivity.

Effect of Land Configuration and Weed Management on Performance of Urdbean [Vigna mungo (L.) Hepper

Background: Blackgram is an important crop among kharif pulses and is usually grown on marginal and sub-marginal lands without proper weed management under rainfed situation. Broad bed furrows had greater influence on plant growth over farmers practice. Weed management through mechanical or manual is normally tedious, labour consuming and costlier. Keeping this in view, the present study was envisaged to investigate integrated effect of land configuration and weed management regimes on productivity of urdbean. Methods: A field experiment was carried out during kharif seasons of 2016 and 2017 at Regional Agricultural Research Station, Lam, Guntur on effect of land configuration and weed management on performance of urdbean (Vigna mungo L.Hepper). The treatments included two land configurations i.e., flat bed and broad bed furrow method allotted as horizontal plots and four weed management practices i.e., weedy check, pendimethalin 30 EC @ 1.0 kg a.i ha-1 PE, imazethapyr 10% SL @ 55 g ha-1 at 15-20 DAS and pendimethalin 30 EC @ 1.0 kg a.i ha-1 PE fb imazethapyr 10% SL @ 55g ha-1 at 15-20 DAS allotted as vertical plots replicated four times in a strip plot design. The comparison of treatment means was made by critical difference (CD) at P less than 0.05 by using standard statistical procedures. Result: Based on the results, it can be concluded broad bed method of land configuration proved its superiority over flat bed method by producing 12.8 per cent higher grain yield besides empowering growth and yield attributes. Among the weed management practices, the highest grain yield (1280 kg ha-1) recorded with pendimethalin 30 EC @ 1.0 kg a.i ha-1 PE fb imazethapyr 10% SL @ 55g ha-1 at 15-20 DAS along with maximum monetary returns and B:C can be recommended for urdbean.

Multi-year weed community dynamics and rice yields as influenced by tillage, crop establishment, and weed control: Implications for rice-maize rotations in the eastern Gangetic plains

In South Asia's rice-based cropping systems, most farmers flood and repetitively till their fields before transplanting. This establishment method, commonly termed puddled transplanted rice (TPR), is costly. In addition, it is labor and energy intensive. To increase labor and energy efficiency in rice production, reduced or zero-tilled direct seeded rice (ZT-DSR) is commonly proposed as an alternative tillage and crop establishment (TCE) option. Effective management of weeds in ZT-DSR however remains a major challenge. We conducted a four-year experiment under a rice-maize rotation in Northwestern Bangladesh in the eastern Gangetic Plains to examine the performance of two TCE methods and three weed management regimes (WMR) on the diversity and competitiveness of weed communities in the rice phase of the rotation. The Shannon-Weiner Diversity Index, a measure of species diversity, was significantly greater under ZT-DSR than puddled TPR. It was also greater under no weed control (Weedy) and two manual weeding (MW) treatments compared to chemical herbicide with manual weeding (C + MW). In DSR Weedy plots, weed communities began shifting from grasses to sedges from the rotation's second year, while in the ZT-DSR and C + MW treatments, sedges were consistently predominant. In both puddled TPR Weedy and TPR C + MW treatments, broadleaves and grasses were dominant in the initial year, while sedges dominated in the final year. There were significant main effects of year (Y) and weed management regime (WMR), but not of TCE. Significant Y × TCE and TCE × WMR interaction effects on rice yield were also observed. Grain yields under ZT-DSR were similar to puddled TPR. ZT-DSR with one application of pre-emergence herbicide followed by one hand weeding at 28 days after establishment however resulted in significantly higher grain yield (5.34 t ha−1) compared the other weed management regimes. Future research should address methods to effectively manage weed community composition shifts in both ZT-DSR and TPR under rice-maize rotations utilizing integrated and low-cost strategies that can be readily applied by farmers in the eastern Gangetic Plains.

Costs and risks associated with surveying the extent of herbicide resistance in New Zealand

ABSTRACT Herbicide resistance has repeatedly developed under intensive herbicidal weed management regimes globally with 255 species having resistant biotypes. In New Zealand, since 1979, resistance was found in 13 taxa, with >25 herbicides in 8 chemical classes showing reduced effectiveness (i.e. HRAC groups A, B, C, D, F, G, H, N and O). Cases included weeds in turf, pastures, orchards, vineyards, forage and arable crops. Surprisingly little is known about the spatial extent or frequency of this problem in New Zealand. We estimate that 14,000 farms have land-use histories like those favouring herbicide resistance historically. Sampling simulations of ≥10% farms provided good estimates of resistance prevalence for most regions and crop types. Acceptable sampling rates varied with target population size, actual resistance prevalence, and detection certainty. Our simulations provide a sobering caution regarding our ability to delimit the problem cheaply or accurately. Detection rates lower than 75% always give imprecise prevalence estimates. Sampling and screening involved 7.4 h labour and 27 km of travel costing $759 NZD per farm. Sampling 10% of farms would cost >$1 million NZD if lower risk farms were excluded, or >$3 million in exhaustive surveys. Regional farm and industry breakdowns could guide cost-sharing arrangements for surveys.

Improving the unsupervised mapping of riparian bugweed in commercial forest plantations using hyperspectral data and LiDAR

Accurate spatial information on the location of invasive alien plants (IAPs) in riparian environments is critical to fulfilling a comprehensive weed management regime. This study aimed to automatically map the occurrence of riparian bugweed (Solanum mauritianum) using airborne AISA Eagle hyperspectral data (393 nm–994 nm) in conjunction with LiDAR derived height. Utilising an unsupervised random forest (RF) classification approach and Anselin local Moran’s I clustering, results indicate that the integration of LiDAR with minimum noise fraction (MNF) produce the best detection rate (DR) of 88%, the lowest false positive rate (FPR) of 7.14% and an overall mapping accuracy of 83% for riparian bugweed. In comparison, utilising the original hyperspectral wavebands with and without LiDAR produced lower DRs and higher FPRs with overall accuracies of 79% and 68% respectively. This research demonstrates the potential of combining spectral information with LiDAR to accurately map IAPs using an automated unsupervised RF anomaly detection framework.

Cropping System Diversity Effects on Nutrient Discharge, Soil Erosion, and Agronomic Performance

Nutrient, herbicide, and sediment loading from agricultural fields cause environmental and economic damage. Nutrient leaching and runoff pollution can lead to eutrophication and impaired drinking water resources, while soil erosion reduces water quality and agronomic productivity. Increased cropping system diversification has been proposed to address these problems. We used the ArcSWAT model and long-term Iowa field experimental measurements to estimate eutrophication and erosion impacts of three crop rotation systems under two weed management regimes. Rotations were comprised of 2-year corn-soybean, 3-year corn-soybean-oat/clover, and 4-year corn-soybean-oat/alfalfa-alfalfa systems. All were managed with conventional or low herbicide applications. Total N and P runoff losses were up to 39% and 30% lower, respectively, in the more diverse systems than the 2-year corn-soybean system, but NO3--N leaching losses were unaffected by cropping system. Diversification reduced erosion losses up to 60%. The 3- and 4-year systems maintained or increased crop yields and net returns relative to the 2-year conventional system. Reductions in herbicide use intensity generally did not affect nutrient and sediment losses nor crop yields and profitability. These results indicate that diversifying the corn-soybean rotation that dominates the central United States could reduce water nutrient contamination and soil erosion while maintaining farm productivity and profitability.

Chemical Weed Control in Paddy Fields Inoculated with Azospirillum lipoferum

ABSTRACT: Herbicides, as a major part of weed control strategy in paddy fields, have different impact on growth and activity of soil-beneficial bacteria such as Azospirillum species. A field experiment was conducted at Sefid Rood Livestock and Agricultural Company, northern Iran, to investigate the possibility of chemical weed control in paddy fields inoculated with Azospirillum lipoferum. The experiment was designed in a factorial arrangement based on a randomized complete block with three replicates. The factors were Azospirillum application (inoculation with or without Azospirillum lipoferum) and weed management regime (butachlor application with supplementary hand-weeding, bensulfuron methyl application with supplementary hand-weeding, combination of butachlor and bensulfuron methyl application with supplementary hand-weeding, hand-weeding at 15, 30, and 45 days after transplanting, and no weeding [not weeded during the rice-growing period). The results showed that plants inoculated with A. lipoferum produced 19% higher grain yield compared to plants that were not inoculated. The highest grain yields were recorded for plots treated with butachlor with supplementary hand-weeding (4,512 kg ha-1) and for those treated with a combination of butachlor and bensulfuron methyl with supplementary hand-weeding (4500.5 kg ha-1). The lowest yield (3494.3 kg ha-1) was recorded for weedy plots. No significant interaction was detected between A. lipoferum application and weed management regime for grain yield, indicating that the herbicides had no adverse effect on the efficiency of A. lipoferum in promoting growth and grain yield of rice. There was no significant difference in the dry weights of weed between inoculated and non-inoculated plots. The dry weights of weed in hand-weeded and herbicide-treated plots were significantly lower than that of the weedy plot. In conclusion, the result of this experiment confirms the possibility of chemical weed control in paddy fields inoculated with A. lipoferum.

The bionomics of whitegrub species (Coleoptera: Scarabaeidae) affecting commercial forestry re-establishment in representative areas of the South African summer-rainfall region

South African commercial forestry plants mainly Eucalyptus, Pinus and Acacia species. Invertebrate pests play a significant role in the establishment phase of these exotic trees. Whitegrubs, in particular, are known to affect seedling survival during this period. Their pest status and community structure patterns associated with slash and weed management regimes were recently reported for Acacia mearnsii in the KwaZulu-Natal (KZN) province. We tested whether the effects of these regimes were congruent over a wider region (the South African summer-rainfall forestry area), including whitegrubs found on Eucalyptus and Pinus species, or if there were other possible factors that better explained the patterns of assembly. Seventeen trials were established in the KZN and Mpumalanga (MP) provinces from which whitegrubs were collected once a month for a period of one year. Multivariate analyses were performed to determine whitegrub prevalence, distribution, pest ranking and community structure patterns. Sixteen whitegrub morphospecies were found of which Maladera sp. 3, Pegylis sommeri, Schizonycha affinis, Maladera sp. 2, Adoretus ictericus, Maladera sp. 1, and the unknown M8, M12 and M14 had a high pest status with an accumulative prevalence of ∼99%. Maladera sp. 3 was the most prevalent and widespread species. It was also the most important species attacking E. grandis and P. patula, whereas P. sommeri and S. affinis were the most important whitegrubs on A. mearnsii. Clustering analyses showed two spatial (regional [2× clusters] and locality [10×]) and one silvicultural (slash and weed management [9×]) patterns of whitegrub assembly. As expected, the slash and weed management clustered the whitegrub communities in the forestry area. However, the two regional clusters (KZN-Midlands, MP-South and KZN-Coastal) were preferred because they visually represented the whitegrub community distribution with a listing of high-status whitegrub species. This was meaningful enough to suggest the possible implementation of site-specific and practical control strategies.

Effects of Tillage, Soil Amendment and Weed Management Regime on Performance of Lowland Rice (Oryza sativa L.) in the Guinea Savannah

Field experiment was carried out during the 2015 and 2016 cropping seasons at Integrated Water and Agricultural Development Limited (IWAD) in the Mamprugu Moaduri district of Northern region. The objectives of the study were to evaluate tillage system, soil amendment and weed management regime on the growth and yield of rice under lowland conditions. The experiment was laid out in split-split-plot design in three replications with tillage, soil amendment and weed management which constituted the main-plot, sub-plot and sub-sub-plot factors respectively. Tillage, soil amendment and weed management, each at three levels, were respectively made-up of zero tillage (ZT), minimum tillage (MT) and conventional tillage (CT); 2.5 tons/ha organic manure, 2 tons/ha biochar and 250 kg NPK/ha; and hand weeding at 3 and 6 weeks after planting (WAP), pre-emergence herbicide, and post-emergence herbicide. Post-emergence herbicide application supported earliest flower initiation (80-85 days) compared to manual weeding (82-92 days) and pre-emergence herbicides (83-90 days). The combination of zero tillage and pre-emergence herbicide weed management gave the highest number of tillers of 34.3 per hill and maximized grain yield (6661 kg/ha). Longest rice root length was 34 cm in zero tillage with compost amendments and pre-emergence herbicide treatments. Soil carbon stock below 40 cm soil depth was highest in zero tillage (0.89% C) compared to minimum tillage (0.65% C) and conventional tillage (0.55 % C). Results gave good indication of best land preparation, soil amendment and weed management practice that could promote sustainable cropping in sandy-loam textured lowland soils. 

Integrated effect of population and weed management regimes on weed dynamics, performance, and productivity of basmati rice (Oryza sativa L.)

Weeds caused serious problem on yield reduction of basmati rice worldwide. Losses caused by weeds varied from one country to another, depending on the presence of dominant weeds and the control methods practiced by farmers; therefore, suitable plant population and weed management practices should be adopted. Keeping these in mind, a field experiment was carried out during kharif seasons of 2009 and 2010 at crop Research Centre of SVPUA&T, Meerut, India comprising 4 planting geometries, viz. 20, 30, 40, and 50 hills m−2 as main plot factor, and 5 weed management practices (Butachlor @ 1.0 kg ha−1, Butachlor @ 1.0 kg ha−1 fb (followed by) one hand weeding, Butachlor @ 1.0 kg ha−1 fb Almix @ 4 g ha−1, two hand weedings and weedy check) in a split plot design with 3 replications. Experimental results revealed that plant population of 50 hills m−2 proved superior over that of 20 hills m−2 in respect of weed density, weed dry weight, number of tillers m−2, yield attributes, grain, straw, and biological yields. The maximum grain yield (29.00 and 31.00 q ha−1) and straw yield (51.30 and 52.50 q ha−1) were recorded in 50 hills m−2 followed by 40 hills m−2 during 2009 and 2010, respectively. In respect of nitrogen, phosphorus, and potassium removal, a reverse trend was observed: the highest in 20 hills m−2 followed by 30, 40, and 50 hills m−2. As far as the weed management practices are concerned, both chemical and mechanical methods of weed control were found superior over weedy check. The lowest weed density, dry weight, and highest weed control efficiency, maximum length of panicle−1, number of panicle (m2), and 1000-grain weight and grain yield of 30.40 and 32.60 q ha−1 were recorded with two hand weedings which was at par with Butachlor @ 1.0 kg ha−1 fb one hand weeding over rest of the weed management practices.

Adapting spring wheat breeding to the needs of the organic sector

Organic farmers and food processors need plant varieties that are adapted to their crop husbandry and processing practices. Such varieties are scarce as the mainstream breeding sector focuses on developing varieties for the conventional product chain that has different goals and practices. In this paper we study the case of the Dutch bread production chain to assess options that might enhance the availability of varieties suitable for the organic sector. The research involves an analysis of organic crop management and food processing practices and associated variety requirements. The research shows that several variety traits prioritized by the organic sector are not adequately addressed by conventional plant breeders: high baking quality, weed suppressiveness and tolerance to harrowing. Some of the interviewed conventional breeders are willing to consider technical adjustments to their breeding programmes. However, seed legislation and company economics limit the space to implement such modifications. We conclude that developing spring wheat varieties for the organic bread production chain requires breeders to prioritize selection for high baking quality genotypes that tolerate an organic weed management regime. This would require a concerted initiative of all actors in the organic bread production chain that includes establishing new socio-economic partnerships to overcome current economic and legal barriers.

Vineyard Colonization by Hyalesthes obsoletus (Hemiptera: Cixiidae) Induced by Stinging Nettle Cut Along Surrounding Ditches.

Stinging nettle (Urtica dioica L.) is the most important host plant for both phytoplasma associated with Bois noir disease of the grapevine and its vector Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae). Vector abundance in vineyards is favored by stinging nettle growing in surrounding areas. Nettle control by herbicides or cutting can reduce vector population in vineyards. However, chemical weeding can cause environmental problems. Many authors suggest that stinging nettle control applied during H. obsoletus flight could force adults to migrate into vineyards. We evaluate if cutting of nettle growing along ditches during adult flight favors vineyard colonization by H. obsoletus. Three different weed management regimes ("no cuts," "one cut" just before the beginning of adult flight, and "frequent cuts" over the whole vegetative season) were applied to the herbaceous vegetation in ditches bordering two vineyards. The flight dynamics of H. obsoletus were recorded by placing yellow sticky traps on the vegetation along the ditches and at different positions in the vineyards. Frequent stinging nettle cuts (compared with a single cut) in surrounding areas favored the dispersion of vectors inside the vineyards. Stinging nettle control should be based on an integration of a single herbicide application before H. obsoletus emergence followed by frequent cuts to minimize negative side effects of chemical weeding. In organic viticulture, a frequent-cuts strategy should avoid cuts during H. obsoletus flight period, at least in the first year of adoption.

EFFECTS OF PLANTING DATE AND SPATIAL ARRANGEMENT ON COMMON BEAN (Phaseolus vulgaris) YIELD UNDER WEED-FREE AND WEEDY CONDITIONS

ABSTRACTTo evaluate the effect of planting date and spatial pattern on common bean yield under weed-free and weed-infested conditions, an experiment was conducted in Kelachay, Northern Iran, in 2013. The experimental design was a randomized complete block in a factorial arrangement with three replicates. Factors were planting date (10 August and 20 August), spatial pattern (square and rectangular planting pattern, with a planting distance of 30 x 30 cm and 45 x 20 cm, respectively), and weed management regime (weed-free and weedy conditions, weeded and not weeded throughout the growing season, respectively). Results showed that the main effect of planting date was significant only for pod number per plant and seed number per pod. At the same time, pod number per plant, seed number per pod, pod length, and grain yield were influenced significantly by spatial pattern. Results of ANOVA have also indicated that all traits, except pod length, were influenced significantly by weed-management regimes. Moreover, effect of planting date and spatial pattern were nonsignificant for weed dry weight. Mean comparison has expressed a significant increment in seed yield for square planting arrangement (1,055 kg ha-1) over rectangular (971 kg ha-1). Weeding has also presented an overall 12% and 8% improvement in grain and pod yield over control (weedy check), respectively. Based on the results of this study, weed control, as well as square planting pattern, are recommended for obtaining the highest seed yield in common bean.

Integrated Effect of Land Configurations and Weed Management Regimes on Weed Dynamics and Performance of Urdbean (Vigna mungo L. Hepper) in an Alluvial Soil

A field experiment was carried out during kharif seasons of 2012 at CRC of SVPUA and T, Meerut to evaluate the weed dynamics and performance of urdbean under integrated effect of land configurations and weed management regimes. The experiment was laid out in split plot design with three replications. In main plot factor, four land configuration i.e. Line sowing (30 cm), Ridge method, Broad bed method (30 cm) and Broadcast sowing and in sub plot factor, four method of weed management practices, i.e. Pendimethalin @ 1.5 kg a.i/ha as pre-emergence, two hand weedings at (20 and 40 DAS), and Quizalofop ethyl @50 gm a.i/ha as post emergence and control were tested by using F test. The study on weeds and crop growth parameters was made on quadrate (1 m2) basis, whereas the yield attributes and yield were calculated on net plot area basis (12 m2). The economical studies were done on the basis of prevailing market prices of input and output. The results indicated that weed population and dry weight of weeds were significantly reduced with the application of Quizalofop ethyl @50 gm a.i/ha as post emergence over Pendimethalin @ 1.5 kg a.i/ha as pre-emergence, Two hand weedings at (20 & 40 DAS) and control. Plant population, growth parameters viz., plant height, number of trifoliate leaves and dry matter accumulation and yield attributes viz., number of pod plant-1, 100 seed weight, biological yield, harvest index found superior by using Quizalofop ethyl @50 gm a.i/ha as post emergence than Pendimethalin @ 1.5 kg a.i/ha as pre-emergence, Two hand weedings at (20 & 40 DAS) and control. This treatment also fetched Rs. 40631 and 53753 net and gross return, respectively. Moreover, under land configurations, Broad bed method (30 cm) showed highest values of above parameters followed by Ridge method, Line sowing (30 cm), and Broadcast sowing. Apart from above it also bring significantly reduction in weed population and dry weight of weeds. Thus, broad bed method in combination with Quizalofop ethyl @50 g a.i./ha as post emergence may be suggested for effective control of weeds in urdbean with maximum net return.