Frequent Weeding Research Articles

The nexus between information sources, gender and adoption of fall armyworm management practices in Southern Ghana

The impact of Fall Army Worm (FAW) infestation on the livelihood outcomes of farmers in Africa is an issue of critical concern. Specificities of information sources and their efficacy in the management of Fall Armyworm remain crucial. Yet still, the nexus between farmers’ information sources and the management of Fall Armyworm appears scarce in the related literature pertaining to the global south. This article answers the research question: What is the relationship between specific information sources and the management practices of Fall Army Worm in Ghana? Using cross-sectional data on 340 smallholder farmers, the findings showed that information derived from peer farmers, Agricultural extension officers, and the media related to the adoption of fall armyworm management practices. Additionally, information from agricultural extension agents has a significant relationship with the use of pesticides, handpicking, and frequent weeding. Generally, the majority (97%) of smallholder farmers remained aware of the presence of FAW and had been negatively affected. We recommend that peer-to-peer extension be harnessed and scaled up in the dissemination of useful agricultural information given the shortfall in adequate agricultural extension officers in Ghana and most countries in Sub-Saharan Africa.

Good agricultural practices (GAP) adoption intensity and production constraints in apple orchards of western Nepal

The declaration of ‘Fruits Decade 2016/17–2026/27’ and the enaction of the ‘NepalGAP Scheme’ by the Government of Nepal has redirected increased public investments to promote apple production and marketability in the western high hills of Nepal. This study explores major good agricultural practices (GAP) related to orchard management, factors influencing their adoption intensity, and key underlying constraints to production using cross-sectional survey data from apple growers in Dolpa district, Nepal. The results showed that farmers mostly adopted GAP such as frequent weeding, intercropping, and nutrient management in apple orchards. Based on the negative binomial regression estimates, household characteristics such as gender of the orchard owner, experience, and number of literate household members were found influential in determining the GAP adoption intensity. The analysis of the problem severity index implied that apple production is mostly constrained by limited access to production inputs and transportation. The findings provide useful insights to the farmers and policymakers regarding the current scenario of GAP adoption along with the diversity of barriers that severely limits the realization of apple production potential in western Nepal.

Analyzing the synergistic impact of UAV-based technology and knapsack sprayer on weed management, yield-contributing traits, and yield in wheat (Triticum aestivum L.) for enhanced agricultural operations

Modern agriculture uses agrochemicals to boost crop yield and quality. Using knapsack sprayers, Indian farmers apply herbicides, insecticides, and other chemicals. Herbicides are applied by manually operated knapsack sprayers, which are laborious, uneven, and prone to human mistakes. Unmanned aerial vehicles (UAVs) are a promising agricultural spraying alternative to manual operations. Future agricultural and field scouting technology aids weed management, pest control, and automated irrigation systems. Drone herbicide spraying was compared to traditional and mechanical knapsack sprayers in this study. The study also tested knapsack (manual) and UAV herbicide pre- and post-emergence and spraying on wheat crops. Herbicide application by knapsack and drones was examined for weed control, yield-contributing characters, and wheat yield. The experiments were performed at Vasantrao Naik Marathwada Krishi Vidyapeeth's Department of Agronomy in Parbhani, Maharashtra. A randomized block design (RBD) with eight treatments, including drones and knapsack sprayers for weed management in wheat crops with different herbicide application times and repeated hoeings (cultural method), was compared to absolute weed-free, where no weeds were allowed to grow in wheat by frequent weeding and weedy inspection. The experimental field measured 7.2 m x 6 m gross land area and 6.3 m x 5.6 m net land area. When winds were light, the drone was flown at 3 m to avoid herbicide droplets drifting. The study found that unweeded wheat yields dropped 38 % owing to weed insects. The pre-emergence (PE) application using a knapsack sprayer and post-emergence (POE) herbicide application via a drone synergistically resulted in the highest growth and yield for T3, attaining values of 11.02 gm/plant, an average of 284.97 grains/plant, and a per-hectare grain yield of 4256.59 kg/ha. The cultural approach of weed management (T4) reduced yield by 21.2 %; however, treatment T3 improved yield contributing characteristics and losses by just 2.8 %. UAV-based herbicide spraying is a fast and easy method that contributes to achieving sustainable development goal (SDG) 2 for Zero Hunger by promoting sustainable plant protection and crop production.

Synergistic effect of straw-mulch and mycorrhiza-biofertilizer in increasing yield of black rice intercropped with soybean on raised-beds in aerobic irrigation system

Application of mycorrhiza-biofertilizer and intercropping with legume crops could improve performance and yield of red-rice grown onraised-beds under aerobic irrigation systems, but weeds became a serious problem, which needs more frequent weeding. A Split Split-Plot (SSP) experiment was designed to examine synergistic effects of rice-straw mulch and mycorrhiza-biofertilizer application on yieldof several black rice promising-lines that were additively intercropped with soybean on aerobically irrigated raised-beds. Three treatmentfactors including black-rice genotypes (G3, G9, G4/15), straw mulching (S0= without; S1= with mulch), and mycorrhiza-biofertilizer(M0= without; M1= with biofertilizer) were arranged as the main, subplots and sub-subplots respectively in three blocks (replications).The results indicated that straw mulch and biofertilizer application significantly increased growth and yield of the black rice plants, whilethe genotypes were also significantly different in several growth and yield variables. However, there were significant interaction effectsof mycorrhiza-genotypes (M*G), mycorrhiza-straw (M*S), and mycorrhiza-straw-genotype (M*S*G) on several growth and yield variables,indicating variation of responses to mycorrhiza among the genotypes. The M*S*G interaction also indicated synergistic effects betweenstraw mulch and mycorrhiza biofertilizer in increasing the black rice yield, in which the S1M1 treatment resulted in the highest grain yieldon the G4/15 line (58.2 g/clump) while the S0M0 treated G9 line showed the lowest yield (29.8 g/clump).

AGRICULTURAL LAND USE PRACTICES AND INTENSITY OF ENVIRONMENTAL DEGRADATION IN NORTH CENTRAL NIGERIA’S ARABLE FARMING LANDSCAPE

Arable land is the most important agricultural production input. Land use, coupled with management practices is the key instrument for achieving environmental security, increase in yield and productivity. This study examined the agricultural land use practices and intensity of environmental degradation among arable farming households in North central Nigeria. A survey of 356 households was used to generate household level data using a well-structured questionnaire. The data collected were analyzed using both descriptive and inferential statistics like means and ordered logistic regression analysis (Ologit). Results showed that land is cultivated intensely and on a continuous basis with mixed-cropping and complete tillage commonly practiced by 83.2% and 67.4% of the farmers, respectively. On the average, arable farmers perceived environmental degradation as having high intensity (2.46) on their farmland. Agricultural land use practices like complete tillage, more frequent weeding, land conflicts, farming on sloppy farmlands increased the intensity of environmental degradation while practices like herbicide use reduced it. The study concluded that improving land use practices is, therefore, a pre-requisite for sustainable agriculture, which is itself a necessary condition for environmental conservation. Hence, extension agents should organize proper teaching of farmers in rural areas on the best ways to cultivate and harvest crops and to take due caution in the choice of equipment for land clearing as well as the technique of land clearing in order to minimize injury to the environment.

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.

Practices and constraints of tomato production among smallholder farmers in Uganda

Tomato(Solanum esculentum)is one of the most promising vegetables whose production is being intensified in Uganda. However, tomato yields remain low due to several constraints. The study aimed at identifying production and marketing practices, and constraints affecting tomato productivity in major tomato growing areas of Uganda. A survey was conducted in eight major tomato producing districts using a questionnaire to guide interviews for 240 farmers and 16 key informants. The data were analyzed using SPSS software. Results revealed that tomato production in Uganda is dominated by males who grow them on 0.68 acres of land on average. Mosttomatofarmers (78.4%) use mono cropping system with varietiesAsilla F1 (35.3%), Tengeru97(21.1%), Rambo (18.1%), NovelaF1(17.7%) and Riogrande (10.3%) dominating. The choice of tomato varieties used by farmers mainly depend on yield potential, pest and disease tolerance and market preference attributes such as long shelf life. In the study area, tomato is mainly fertilized using foliar fertilizers, followed by Diammonium phosphate and cattle manure. The key pests affecting tomato include caterpillars, thrips, worms and whitefly, while bacterial wilt, blight, leaf spots and viral infections are the major diseases. Majority (95.7%) of farmers use chemical sprays(pesticides and fungicides)and 4.3% of farmers used other control methods. The other methods of pest and disease control included rogueing, hand picking, ash, organic extracts, urine and frequent weeding. Average tomato yield was 4,846.3 kg/acre lower than the potential yield of 6000kg/acre. Thirty five percent of farmers market their tomato individually on-farm, 32.8% sell in rural markets, while 32.2% send to the nearest urban markets. The study revealed intensive chemical use accounting for 20% of the production costs, high seed costs (11%) and drought (10%) as the major production constraints impeding tomato production; and price fluctuations, low prices, high transport costs, post-harvest loss on farm, and poor market access as the major marketing constraints. The research findings will aid in the development of new market-oriented, highly productive tomato varieties with improved access to seed and designing initiatives to address production and marketing constraints, which will eventually enhance tomato production.

Evaluation of Different Designs of Isolated Cells to Raise Single Rice Seedlings for SRI Mechanized Transplanting

Numerous benefits of the system of rice intensification (SRI) have been documented since SRI was popularized 30 years ago. To date, more than 58 rice growing countries are practicing SRI, covering around 4 million ha of paddy fields and involving more than 10 million farmers. Many paddy farmers shy away from practicing SRI due to extreme labour endurance and number of labors required, especially during transplanting and frequent weeding. The manual transplanting technique to ensure proper root establishment of the seedlings, makes SRI less appealing to many paddy farmers. Furthermore, the transplanting shock is a problem arises from manual transplanting technique needs to be solved that resulted to damaged roots causing delays in crop establishment and reducing productivity. Mechanized transplanting of the young single seedlings into the paddy fields at a wider plantation area eliminates drudgery and enables better exposure to sunlight, water, air, and nutrients. This paper presents a solution to overcome the problem of transplanting shock and the back-breaking manual transplanting, which was achieved by containing the roots of each seedling in a grid of isolated cells. Several designs of the isolated cells to contain the root system were fabricated and tested. These include using aluminum square cells, polyvinyl chloride pipe circular cells, biodegradable grid cells, biodegradable conical capsules, and germinated seeds sowed in a grid without isolated cells. The typical grid cell size was 15 mm by 15 mm with a depth of each cell varied from 40 mm to 60 mm. The most promising design was one with single seedlings raised in bio-degradable capsules arranged close together to fit the conventional rice seedling tray of 300 mm by 600 mm and can accommodate 684 capsules per tray. Upon reaching 2-3 leaf stage, the seedlings with undisturbed roots are ready to be transplanted into the paddy fields using the currently available rice transplante rs.

Effect of herbicidal weed management on growth, yield attributes and productivity of Lathyrus (Lathyrus sativus L.) for Chhattisgarh

The present research entitled “Effect of herbicidal weed management on growth, yield attributes and productivity of Lathyrus (Lathyrus sativus L.) for Chhattisgarh" was conducted during Rabi season of 2020-21 at the Instructional Farm, College of Agriculture, Raipur (CG). The soil of experimental site was sandy loam, poor in available nitrogen, medium in available phosphorus and rich in potassium contents with neutral pH. The experiment was laid out in Randomized Block Design with three replications. The treatments consisted of fifteen weed management practices viz, T1: Oxadiargyl @ 80 g/ha 0-3 DAS, T2: Metribuzin @ 350 g/ha 0-3 DAS, T3: Topramezone @ 19.35 g/ha 2-3 Leaf stage of weed, T4: Topramezone @ 25.8 g/ha 2-3 Leaf stage of weed, T5: Topramezone @ 32.25 g/ha 2-3 Leaf stage of weed, T6: Topramezone (directed application) @ 25.8 g/ha 5-6 Leaf stage of weed, T7: Fluzifop-p-butyl 13.4 % + Fomesafen 11.1 % (directed application) @ 250 g/ha 5-6 Leaf stage of weed, T8: Metribuzin @ 350g/ha fb Topramezone @ 25.8 g/ha at 0-3 DAS & 2-3 Leaf stage of weed, T9: Metribuzin @ 350g/ha fb Metribuzin @ 350 g/ha at 0-3 DAS & 5-6 Leaf stage of weed, T10: Fluzifop-p-butyl 13.4 % + Fomesafen 11.1 % @ 250 g/ha 2-3 Leaf stage of weed, T11: Sodium acifluorfen 16.5 %+ clodinafop proparzyl 18 % (directed application) @ 187.5g/ha 2-3 leaf stage of weed T12: Mertibuzin (directed application) @ 350 g/ha 2-3 leaf stage of weed, T13: Metsulfuron (directed application) @ 4 g/ha 2-3 leaf stage of weed, T14: Hand weeding twice 20 & 40 DAS and T15: Unweeded control. The Lathyrus variety Prateek was sown on November 15, 2020 and harvested on March 8, 2021. The experimental finding showed that the growth characteristics viz. plant population, plant height, number of branches/plant, dry weight accumulation (g/plant), number of nodules/plant, dry weight nodules/plant and crop growth rate and yield attributes viz., number of seeds/plant, number of seeds/pod, seed yield, Stover yield, 100 seed weight and harvest index were found significantly superior in Hand weeding twice 20 & 40 DAS (T14), over other weed management practices but was at par with treatment T9: Metribuzin @ 350g/ha fb Metribuzin @ 350g/ha at 0-3 DAS & 5-6 Leaf stage of weed. The lower values of above characters have been observed in the unwedded control (T15) followed by Fluzifop-p-butyl 13.4 % + Fomesafen 11.1 % @ 250 g/ha 2-3 Leaf stage of weed (T10). Predominant weed species Medicago denticulate L., Cichorium intybus L., Chenopodium album L., Melilotus indica L, Alternanthera sessilis L, Echinochloa colona L. and Physallis minima L, intensified in the experimental field. Hand weeding twice 20 & 40 DAS (T14) followed by Topramezone @ 32.25 g/ha 2-3 Leaf stage of weed (T5) observed in effectively reducing weed density, weed dry matter accumulation, lowest weed growth rate and thus providing maximum weed control efficiency and weed control index. While, the weed index was higher at Unwedded control (T15). In term of economic returns, the gross returns and net return was maximum under Hand weeding twice 20 & 40 DAS (T14) followed Metribuzin @ 350 g/ha fb Metribuzin @ 350 g/ha at 0-3 DAS & 5-6 Leaf stage of weed (T9), whereas, net return and B: C ratio was maximum under Metribuzin @ 350 g/ha fb Metribuzin @ 350 g/ha at 0-3 DAS & 5-6 Leaf stage of weed (T9). This might be because of higher cost of cultivation due to continuous frequent weeding in Hand weeding twice 20 & 40 DAS plot (T14).

How to increase the productivity and profitability of smallholder rainfed wheat in the Eastern African highlands? Northern Rwanda as a case study

As wheat demand is increasing in sub-Saharan Africa (SSA), domestic production is being encouraged. The potential to increase the productivity and profitability of wheat appears large in the region, but little is known about the concrete interventions needed to meet that potential. In this study, we selected a site in Northern Rwanda (representative of the cool humid climatic zone which accounts for most of the spring wheat production of SSA) and analysed the determinants of wheat productivity and profitability for 130 smallholder farms during two consecutive short rainy seasons, namely 2017A and 2018A (wheat is seldom grown during long rainy seasons: potato is the preferred crop then). Although wheat yields were found to be high when compared to typical yields in SSA (means of 3469 and 3052 kg ha−1 during the seasons 2017A and 2018A, respectively), large yield gaps were also found (1.977 t ha−1 on average, or 37.6% of the highest farmer’s yield, defined as the average actual yields above the 90th percentile of this variable). Evidences presented in the paper suggest that wheat productivity could be increased through increased seeding rate (a 0.14% increase in wheat grain yield was found with a 1% increase in seeding rate), increased nitrogen (N) application combined with frequent weeding (a 0.02% increase in wheat grain yield was found with a 1% increase in N application and frequent weeding), and labour-saving technologies (e.g., herbicides and mechanization). If wheat profitability would also increase with frequent weeding and labour-saving technologies, it would decrease with increased input use in many cases. Indeed, seed, fertilizer and amendments represent most of the wheat production cost in the area. These results illustrate the importance of assessing the impact of narrowing the yield gap on profitability, not only productivity, as some yield-increasing technologies may not be desirable from an economic perspective. They also demonstrate that resource-saving technologies (input-saving e.g., precision agriculture, labour-saving e.g., mechanization) may be as much in demand by African smallholders as yield-increasing technologies, calling for a more balanced approach in current research and development initiatives on the continent.

Understanding the factors influencing fall armyworm (Spodoptera frugiperda J.E. Smith) damage in African smallholder maize fields and quantifying its impact on yield. A case study in Eastern Zimbabwe

Fall armyworm (FAW, Spodoptera frugiperda J.E. Smith) is an invasive lepidopteran pest established in most of sub-Saharan Africa since 2016. Although the immediate reaction of governments has been to invest in chemical pesticides, control methods based on agronomic management would be more affordable to resource-constrained smallholders and minimize risks for health and the environment. However, little is known about the most effective agronomic practices that could control FAW under typical African smallholder conditions. In addition, the impact of FAW damage on yield in Africa has been reported as very large, but these estimates are mainly based on farmers' perceptions, and not on rigorous field scouting methods. Thus, the objectives of this study were to understand the factors influencing FAW damage in African smallholder maize fields and quantify its impact on yield, using two districts of Eastern Zimbabwe as cases. A total of 791 smallholder maize plots were scouted for FAW damage and the head of the corresponding farming household interviewed. Grain yield was later determined in about 20% of these fields. FAW damage was found to be significantly reduced by frequent weeding operations and by minimum- and zero-tillage. Conversely, pumpkin intercropping was found to significantly increase FAW damage. FAW damage was also found to be higher for some maize varieties, although these varieties may not be the lowest yielding. If the incidence of plants with FAW damage symptoms recorded in this research (32–48%, depending on the estimate used) is commensurate with what other studies conducted on the continent found, our best estimate of the impact of FAW damage on yield (11.57%) is much lower than what these studies reported. Although our study presents limitations, losses due to FAW damage in Africa could have been over-estimated. The threat that FAW represents for African smallholders, although very real, should not divert attention away from other pressing challenges they face.

English

The phenomenon of climate change has negative impacts on rice production in Nigeria as it lowers its output and reduces farmers’ income with a resultant depreciation in their livelihood. This accentuates the need for adaptation to climate change in order to reduce the growing dependency on rice importation, ensure food security as well as achieve a sustainable rice production system in Nigeria. The study therefore investigated the utilization of climate change adaptation strategies among rice farmers in three states of Nigeria. Data were collected from 298 rice farmers using interview schedule in Ebonyi, Ekiti and Niger States on their socio-economic and farm enterprise characteristics, knowledge and utilization of Climate Change Adaptation Strategy (CCAS). Data analysis was done using Statistical Package for Social Sciences (SPSS) and analysis of variance (ANOVA). Knowledge of CCAS was high (55.7%) among respondents while utilization of CCAS was low (65.4%). A non-significant difference existed in the use of CCAS across the states (F = 43.15; p-value>0.05). However, continuous and frequent weeding, appropriate use of fertilizer, and early harvesting of crops were major CCAS used by respondents. The result implies that rice farmers are not totally ignorant of CCAS, but have been using one form of adaptation strategy or the other irrespective of the agro-ecology. Also, the study revealed that CCAS is ecology specific thus effective utilization should be ensured.   Key words: Climate change, adaptation strategies, utilization, rice farmers.

Socio-Economic Determinants of Cocoyam Farmer’s Strategies for Climate Change Adaptation in Southeast Nigeria

The study assessed cocoyam farmers strategies for climate change adaptation in Southeast Nigeria. Multi-stage sampling technique was used to select sample for the study. Data were collected using structured questionnaire and Interview schedule and analysed using mean, frequency count, percentages and multinomial logit regression analysis. Findings showed that respondents were mainly women (67%), married (92%) and between the ages of 41 and 60 (52%) with a mean household size of 6 persons. Mean number of years spent in school was 10 years. Majority (40%) earned monthly income of ₦20,000 and below. Average farming experience was 21 years with mixed cropping (71%) as the major cropping pattern while combination of livestock and crop production (48%) was the major farming activity done. Farm size was mainly one hectare and below (64%) which was accessed mainly through inheritance (76%) and farm labour sourced through hired labour (50%). Major crops cultivated was cassava followed by maize and yam. Major adaptation strategies used by the cocoyam farmers in the study area include increased use of organic manure (42%), frequent weeding (10%), application of indigenous knowledge (20%), use of information from extension agents (16%), use of fallowing (9%) and application of multiple cropping (3%). Choice of adaptation strategies used by cocoyam farmers was influenced by age, gender, location of farmer, monthly income and labour. Based on the result of the study, it was recommended that gender and location specific adaptation strategies that are within the financial status of the farmers should be emphasized.

English

Small holder farmers in the semi-arid areas have not been able to utilize seasonal climate forecasts in making crop management decisions due to limited exposure as well as failure to interpret it. Three participatory meetings were held with farmers in Lower Gweru and Lupane Districts of Zimbabwe soon after the release of the 2008/2009 and 2009/2010 seasonal climate forecast in September of each season. This was done to solicit for farmers’ prediction of the coming rainy season and come up with field test crop management practices. Farmers have their sets of indicators that they rely on to forecast seasonal rainfall which are based on generations of past experience that include environmental, biological, and traditional beliefs. There is however, need to investigate how their indicators compare with the scientific forecast in making farming decisions. Farmers claimed that the rains were starting later and finishing earlier whilst analysis of the rainfall record showed that starting rains have been later by 5 to 10 days in the last five years. There was an increase in the number of dry spells in the rainy season in the last five years compared to the period 1980 to 2008. Adding recommended amounts of fertilizers resulted in yield increases of 40% compared to adding half the recommended amounts. Growing long season varieties resulted in higher yields (22%) than growing short season varieties in the 2009/2010 wetter season while growing of shorter season variety had yield advantage (36%) over the long season variety in the 2009/2010 which was relatively dry. Frequent weeding resulted in about 8% increase in maize yields compared to weeding once in a season. The study demonstrates that knowledge of the coming season assists smallholder farmers in coming up with adaptive strategies for climate variability and change.   Key words: Seasonal climate forecast, agriculture, smallholder farmers, adaptation, semi-arid areas.

Growth and Yield Performance of Cowpea (Vigna Unguiculata (L.) Walp) as influenced by Row-Spacing and Period of Weed interference in South-West Nigeria

Weed problem appears to be the most deleterious factor causing between 25 and 60% reduction in potential yield of cowpea. Field trials were therefore conducted to study the effect of inter-row spacing and period of weed interference on growth and yield of cowpea (Vigna unguiculata (L) Walp) at the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta (07° 15'; 03° 25' E) in South Western Nigeria during the early and late wet seasons of 2009. The experiment consisted of eight main plots of weed interference which included initial weed removal for 3, 6, 9, and 12 weeks after sowing (WAS) and subsequently weed –infested until harvest as well as initial weed infestation for corresponding periods and thereafter kept weed free until harvest. There were also sub-plot treatments of three inter-row spacing of 60, 75, and 90 cm. All treatments in different combinations were laid out in a split-plot design with three replications. In both trials, the use of inter-row spacing of 60 cm resulted in significant reduction in weed growth as evident in lower weed dry matter production and subsequent higher cowpea pod and grain yields than those of 75 and 90 cm inter-row spacing. Initial weed infestation of up to 3 WAS did not have any adverse effect on crop growth and cowpea grain yields provided the weeds were subsequently removed. On the other hand, cowpea grain yield loss was not significantly averted by keeping the crop weed free for only 3 WAS without subsequent weed removal. In this study, initial weed-infestation for 6 WAS and beyond significantly depressed various crop growth parameter and cowpea grain yield compared with the crop kept weed free throughout its life cycle. In order to obtain optimum yields similar to that of the weed free cowpea field, it was required to keep the crop weed free for 6 WAS and beyond. However, frequent weeding beyond 9 weeks after sowing did not improve cowpea yield significantly and as a matter of fact it may even result in reduction of cowpea grain yield due to mechanical damage of hoe weeding. The practical implication of this finding is that early weeding starting from 3 WAS is very crucial for cowpea production while the critical period of weed removal for optimum yield in cowpea is between 3 and 9 WAS in the forest-savannah transitional zone of south Western Nigeria.

Fluorescent pseudomonadscontribute to the enhanced growth and yield of rice cultivated under system of rice intensification (SRI)

The System of Rice Intensification (SRI) is an innovative method of rice (Oryza sativa) cultivation that combines many farm practices. Though the benefits of SRI are obvious, the underlying principles in enhanced yields are not yet scientifically analyzed. Two important components of SRI are keeping the rice field moist without flooding and frequent weeding out practices that enhance the aerobic conditions which in turn improve soil biological activity including enhanced root growth and activity of aerobic soil organisms. We have taken up the present investigations, with the premise that soil microorganisms especially fluorescent pseudomonads (FLPs), whose role in enhancement of plant growth is unequivocal, may contribute to the enhanced growth and yield of rice cultivated under SRI.The results of present investigations revealed that rice cultivated under SRI harboured more the population of FLPs in rhizosphere than non-rhizosphere soil. Screening of rhizospheric FLPs isolates has revealed that many of the isolates possessed the ability of producing growth promoting substances like IAA, GA, siderophores, ‘p’solubilization. Some selected strains have also shown resistance towards heavy metals, salts and pH. They have also exhibited significant antifungal activity and enhanced the seed germination and efficient root colonization. Further, artificial inoculations have also clearly shown to enhance the growth in terms of height, dry weight of shoot and root. Thus, the results substantiate the role of FLPs for the enhanced growth and yield of rice cultivated under SRI.

Dealing with weedy problems in agriculture: the role of three agricultural land use management practices in the forest‐savanna ecological zone of Ghana

An important limiting factor on labour‐intensive small‐scale agricultural production in Ghana is competition from weeds for environmental resources, such as soil nutrients, moisture and sunlight. This article combines primary social research based on surveys and in‐depth interviews, and ecological research based on experiment and secondary research to explore the efficacy of three land use management practices, compared with their alternatives, in dealing with on‐farm weed problems in Gyamfiase‐Adenya‐Obom, Ghana. The fallow management practice of >3 years of fallow showed significantly greater promise of suppressing weeds than ≤3 years of fallow. Mulching slashed vegetation, as a land preparation practice, was also consistently better at reducing weed densities than burning the slashed vegetation. The study indicated that while more frequent weeding was generally more effective in suppressing weed densities than less frequent weeding, the effect of weeding in significantly reducing weed densities was not associated with weeding frequency per se but with how carefully weeding was accomplished.

Circle Weeding in Young Oil Palm Using a Hand-held Motorised Grass Cutter

The use of Mucuna bracteata as a ground cover in oil palm plantations brings with it a serious drawback i.e. its rapid growth necessitates very frequent weeding of the circles resulting in higher requirement of workers and higher cost of weeding. By using a motorised hand-held grass cutter a worker could weed slightly more than thrice the number of circles achieved by manual weeding and the cost saving per hectare per round could be reduced by Rp 42 870 (10115.88). Keywords : Circle weeding, motorised cutter, Mucuna bracteata, oil palm.

Strategy of Echinochloa oryzicola Vasing. for survival in flooded rice

Echinochloa oryzicola Vasing. (= Echinochloa phyllopogon Stapf ex Kessenko) is an obligate weed with an elaborated survival strategy in the flooded rice of Japan. In this review various adaptive characters of the weed, which comprise the survival strategy, are discussed through the life cycle. The weed is distributed only in flooded rice. Seeds (spikelets) buried in the soil exhibit annual cycles between dormant and non‐dormant state, and non‐dormant seeds recurrently appear in spring when rice growers start to prepare seedling beds and fields for rice transplanting. The non‐dormant seeds have unique characters metabolically adapted to submerged conditions to germinate and grow by the anaerobic respiration through alcohol fermentation. The weed has seemingly perfect mimicry of the rice plants throughout its development from seedling to heading, by which the weed escapes from manual weeding. In a rice paddy, the weed starts heading coincidentally with the rice plants at the period when the growers are reluctant to walk in the rice paddy to weed. Irrespective of plant height of the rice cultivar, the weed develops a few upper leaves above the rice canopy during the heading period of rice. This phenotypic plasticity of E. oryzicola in plant height is one of the characters conferring its competitive aggressiveness in flooded rice. When weeding is begun again after heading, the dormant weed seeds escape weeding by shattering and join the soil seedbank. The dormant seeds express the gene of an enzyme catalyzing ATP synthesis through the mitochondrial oxidative phosphorylation more abundantly, and have larger oxygen absorption and enzyme activity of the aerobic respiration than the non‐dormant seeds, suggesting that the dormant seeds maintain viability by the conventional aerobic respiration in the paddy soil drained from rice harvesting in fall to the next early spring. The various adaptive characters comprising the survival strategy of E. oryzicola in flooded rice consist of those inherited from the wild progenitor and those selected by the crop cultivation pressure. It is suggested that both the mimicry of the weed and the heading coincident with the rice plants have been acquired by the large selection pressure of frequent weeding, which has been done over the past hundred years. However, today, the manual weeding is substituted with herbicides, which cannot detect the mimicry and heading photoperiodic sensitivity. As a result, the dominant species of Echinochloa weeds in flooded rice is changing from E. oryzicola to Echinochloa crus‐galli var. crus‐galli that has neither mimicry nor photoperiodic sensitivity synchronizing to that of rice, but is more competitive against rice.

Weed Control in Soybean (Glycine max)in Vertisols of Sudan

Abstract The effect of different times of weed removal and the influence of some pre‐emergence herbicides on Soybean (Glycine max (L.) Merr.) were studied in four experiments in the vertisols of central Sudan. Full season competition of weeds reduced seed yield by 78–100%. Delay in first handweeding beyond 30 days after sowing adversely affected the soybean yield and three hand weedings at intervals of 15 days were necessary for adequate weed control and high yield. Both unweeded and late weeding reduced N% in leaves at flowering to about 1.6% compared with 2.8% with frequent weeding. The most successful herbicides for control of the dominant weeds Echinochloa pyramidalis (Lam.) Hitch and Chase and Rottboellia cochinchinensis (lour.) W. D. Clayton were oxadiazon at 1.43 kg/ha and oxyfluorfen at 0.48 kg/ha. Pendimethalin and metolachlor gave satisfactory control of most grasses (72–91%), but many broad leaved weeds were resistant to both herbicides. Metobromuron did not give effective weed control and caus...