Highest Weed Density Research Articles

Impact of Integrated Weed Management Strategies on Weed Density and Biomass in Rice (Oryza sativa L.)

To assess the effectiveness of various weed management practices on controlling weed density and dry weight in rice (Oryza sativa L.). A field experiment was carried out during 2022 and 2023 at the Crop Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, in the Indo-Gangetic plains In Randomized Block Design (RBD) with 12 treatments, each replicated thrice. The treatments included a weedy check, a weed-free condition, farmer’s practice of one hand weeding at 40 days after transplanting (DAT), Pyrazosulfuron applied at 150 g ai ha-1 as a pre-emergence herbicide, Pyrazosulfuron 150 gm ai ha-1 followed by one hand weeding at 40 DAT, Bispyribac sodium at 25 g ai ha-1 applied 15 days after transplanting as a post-emergence herbicide, Bispyribac sodium at 25 g ai ha-1 followed by one hand weeding at 40 DAT, Ethoxy sulfuron applied at 20 g ai ha-1 as a pre-emergence herbicide, Ethoxy sulfuron 20 gm active ingredient per hectare followed by one hand weeding at 40 DAT, Penoxsulam applied at 22 g ai ha-1as a post-emergence herbicide, Penoxsulam 22 g active ingredient per hectare followed by one hand weeding, and a combination of Pyrazosulfuron 150 gm active ingredient per hectare as pre-emergence, followed by Penoxsulam 22 g ai ha-1 as post-emergence, and one hand weeding at 40 DAT. Weed density and dry weight were recorded at 30, 60, and 90 days after transplanting using quadrat sampling. The weed-free treatment consistently exhibited the lowest weed density and dry weight across both years, whereas the untreated weedy check resulted in the highest weed density and dry weight throughout the study. Among the herbicide treatments, the combination of Pyrazosulfuron and Penoxsulam with one hand weeding was found to be the most effective in significantly reducing weed density and dry weight.

Agroecological approach in organic greenhouse vegetable systems: weed communities and functional traits dynamics

ABSTRACT Practices increasing agrobiodiversity and ecological services are the first step toward an agroecological approach to organic greenhouse production. In this study, we compared innovative, diversified, and less intensive greenhouse systems (INNs) with business as usual (BAU) at three European sites (Belgium, Switzerland, and Italy). We evaluated the management effects on weed community composition, diversity, and traits distribution. In comparison with BAU, the INNs had higher weed density (up to +663%) in the three sites, over the entire rotation, higher species richness in Belgium, and lower community evenness in Italy and Switzerland. We observed changes in the distribution of traits between INN and BAU systems at the three sites, but without a clear pattern. Changes in the functional profiles were observed even though the communities were characterized by few and dominant species. The results showed a shift in weed communities between the systems in terms of weed species distribution and functional traits. Despite this, the INN systems did not exhibit a clear trend toward promoting more service-oriented communities compared to the BAU systems.

ANALYSIS OF EFFECTIVENESS AND PROFITABILITY OF SELECTED WEED CONTROL METHODS FOR COWPEA [Vigna unguiculata (L.) Walp] PRODUCTION IN THE SUDAN SAVANNA ECOLOGY OF NIGERIA

Weed management is crucial and expensive step towards cowpea production. Field experiments were conducted during the wet season of 2019 and 2020 at the Research and Teaching farm of the Faculty of Agriculture, Bayero University Kano to evaluate the effectiveness and profitability of selected weed management using weedy check (control), hoe weeding at 3 and 6 weeks after sowing (WAS), metolachlor at 2.0 kg a.i.ha-1, imazethapyr at 3.0 kg a.i.ha-1, pendimethalin at 2.0 kg a.i. ha-1, pendimethalin at 3.0 kg a.i ha-1, pendimethalin 1.0 + imazethapyr 1.0 kg a.i.ha-1, metolachlor 1.5 + pendimethalin 1.5 kg a.i.ha-1, imazethapyr 1.0 + pendimethalin 1.0 kg a.i.ha-1 + SHW at 6 WAS, metolachlor 1.5 + pendimethalin 1.5 kg a.i.ha-1 + SHW at 6 WAS, metolachlor at 2.0 + SHW at 6 WAS, pendimethalin at 2.0 + Supplementary hoe weeding (SHW) at 6 WAS. Weedy check plots yielded significantly (P < 0.01) higher weed density and dry weight than hoe weeded plots at 3 and 6 WAS, Pendimethalin and Metolachlor each at 2.0 + SHW at 6 WAS, which produced lower density and biomass, albeit comparable to other herbicidal-treated plots across the two seasons. Similarly, the application of two hoe weeding’s at 3 and 6 WAS and Metolachlor and Pendimethalin at 2.0 + SHW at 6 WAS significantly resulted in producing higher branches, pods plant-1, pod yield and fodder yield than weedy check. The result of the profitability analysis shows that the highest and lowest gross margin was obtained under pendimethalin at 2.0 kg a.i.h-1 + SHW at 6 WAS (₦164,385/ha) and weedy check (₦28,020/ha), respectively. The average gross income (2019/2020) season was highest under hoe weeding at 3 and 6 WAS, which could be connected to high yield, however, its gross margin ratio (53%) decreased lower than treatments under pendimethalin and metolachlor each at 2.0 kg a.i.h-1 + SHW at 6 WAS (56% and 55% respectively) which is associated with labour cost. For efficient management of cowpea weeds in Nigerian Sudan savanna ecology, application of pendimethalin and metolachlor at 2.0 kg a.i.h-1 + SHW at 6 WAS could be recommended due to their financial and economic advantages.

Allelopathic Effects of Residues of Fimbristylis dichotoma Along with Manures and Fertilizers on the Weed Growth in Boro Rice

Currently, the rice-growing system seeks a biological solution to reduce the negative impacts of chemical herbicides because it is heavily reliant on these for weed control. This is where allelopathy comes in; it's a potential substitute for conventional weed management strategies in rice cultivation by making use of allelopathic plant residues. In the study we used Fimbristylis dichotoma residues with several organic sources of nutrient to measure the integrated effect of manures, fertilizers, and Fimbristylis dichotoma residues on weed growth in boro rice field. Two rice varieties viz., BRRI dhan29 and BRRI dhan89; and six treatments total viz., Control (T1), Residues @ 3 t ha-1 + Recommended doses of inorganic fertilizers (T2), Residues @ 3 t ha-1 + Tricho-compost @5 t ha-1 (T3), Residues @ 3 t ha-1 + Tricho-compost @1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers (T4), Residues @ 3 t ha-1 + Tricho-compost @2.5 t ha-1 + 50% less than recommended doses of inorganic fertilizers (T5) and Residues @ 3 t ha-1 + Tricho-compost @3.75 t ha-1 + 75% less than recommended doses of inorganic fertilizers (T6) were taken. In the experiment, at 25 DAT (days after transplanting), BRRI dhan89 had the highest weed density (35.0) when no residue was applied, and BRRI dhan29 had the lowest (18.00) when 3 t ha-1 F. dichotoma residue with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. At 55 DAT, BRRI dhan89 had the highest weed density (19.66) when no residue was administered, and the lowest (10.66) when 3 t ha-1 F. dichotoma residue was applied along with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers. When it came to dry weight, at 25 DAT, BRRI dhan89 had the highest weed dry weight (3.76 g) when no residue was applied, and BRRI dhan29 had the lowest (1.72 g) when 3 t ha-1 F. dichotoma residue with Tricho-compost @1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. At 55 DAT, BRRI dhan89 had the highest weed dry weight (2.29 g) when no residue was sprayed, and the lowest (1.46 g) when 3 t ha-1 F. dichotoma residue with Tricho-compost @ 1.5 t ha-1 + 25% less than recommended doses of inorganic fertilizers were applied. The study's findings suggest that applying F. dichotoma residue and incorporating Tricho-compost @ 1.5 t ha-1 + 25% less than the recommended amounts of inorganic fertilizers may be able to suppress the growth of weeds and could a package in biological weed control strategy.

Soil and weed management effects on floral hemp (Cannabis sativa L.) production and cannabinoid content

AbstractMany floral hemp (Cannabis sativa L.) growers rely on tillage and black plastic mulch to prepare soil for transplants, warm the soil, and control weeds. However, plastic waste and its high cost to growers drive the need for research to assess alternative weed and soil management practices. Experiments were conducted at two Maine locations in 2021 and 2022 to compare cover crop soil and weed management systems on hemp production, cannabinoid concentrations, and yield. Experimental treatments included (1) tilled raised bed‐black plastic mulch, (2) biweekly cultivation, (3) no weed control, and (4) mowed no‐till mowed winter rye (Secale cereale L. Aroostook). Experimental sites received twice the 30‐year monthly average rainfall in July and September 2021 leading to poorer production versus typical 2022 long‐term average rainfall. Ice damage reduced winter rye biomass in 2022 at University of Maine Rogers Farm, leading to several significant year by location and year by weed management interactions. Hemp grown in the no‐till winter rye mulch developed more slowly, produced lower yields, and had higher weed densities than cultivated or black plastic mulch treatments. Plant size, yield, and cannabinoid content were generally equivalent where weeds were controlled. Raised bed‐black plastic soil and weed management were most effective under excessively wet conditions to reduce soil moisture and improve drainage. Cannabinoid concentrations did not increase under high weed pressure, but cannabinoid yield was influenced by flower production, which was significantly lower in the mowed rye mulch and control treatments. Blending raised bed production with efficient cultivation warrants research attention.

Organic farming practices increase weed density and diversity over conventional practices: A meta-analysis

Population growth and climate change challenge our food and farming systems and provide arguments for an increased intensification of agriculture. Organic farming has been seen as a promising option due to its eco-friendly approaches during production. However, weeds are regarded as the major hindrance to effective crop production which varies depending on the type of crop and spacing. Their presence leads to reduced yield, increase in harvest cost and lower the qualities of some produce. Thus, weed management is a key priority for successful crop production. Therefore, we conducted a meta-analysis from published studies to quantify possible differences on weed density, diversity and evenness in organic and conventional farming systems and best intervention for weed management in organic farming system. Data included were obtained from 32 studies where 31 studies with 410 observations were obtained for weed density, 15 studies with 168 observations for diversity, and 5 studies with 104 observations for evenness. Standard deviation of mean was obtained from the studies, log transformed using natural logarithms and the effect size pooled using standardized mean difference (SMD). Publication bias was determined through funnel plot. Results showed that organic farming has significant higher weed density (P < 0.01), diversity (P = 0.01), and evenness (P < 0.05) compared to conventional farming. Despite so, diversified crop rotation has been proved to reduce weed density in organic farming by up to 49 % while maize-bean intercropping decrease densities of Amaranthus ssp, Cyperus ssp and Cammelina ssp compared with monocropping. Use of mulch after one hand weeding was found to control up to 98 % of weeds and use of cover crop between 24 % and 85 % depending on the type of the cover crop. The study results show that organic farming encourages high weed density, diversity and evenness but use of the integrated approaches can help to maintain weed density at a manageable level.

First Record of Milk thistle (&lt;i&gt;Silybum marianum&lt;/i&gt;, Asteraceae) as Invasive Weed Species in Urban Green Areas of Addis Ababa City, Ethiopia

With increasing globalization and trade, the rate of invasive species entering and spreading has significantly increased globally. These include various invasive insect pests, pathogens, and weeds. Since three years ago, Milk thistle, Silybum marianum, an invasive weed species, has been observed widely in urban green spaces and roadsides in Addis Ababa city, Ethiopia. Weed surveys were conducted across 42 urban green sites located in Yeka, Lemi Kura, Bole, Nifas Silk-Lafto, Kolfie Keraniyo, Akaky Kality, and Gullele sub-cities during the main rainy season from June to September 2023, with the main objective of determining the current distribution of the weed in Addis Ababa city. The urban green areas were selected by using purposive sampling techniques. Field observations confirmed that Silybum marianum can invade and colonize wide habitats and is a highly competitive invasive weed to other important native plant species. High weed density rates and dense stands of weeds were recorded in the 34 urban green areas sampled. The survey result strongly suggests fast integrated weed management options such as mowing/tilling, weeding before the plant goes to seed, cutting (stems and/or seed heads), and burning (collected plant parts and/or seed heads) into a prepared burrow were done to minimize the spreading of the weed and its ecological impacts. The purpose of this survey study is to provide information about Silybum marianum to minimize or avoid its distribution and associated impacts by following sustainable invasive weed management programs in the city before spreading to other cities in the country.

The first record of milk thistle (Silybum marianum, Asteraceae) as an alien invasive weed species in Addis Ababa City, Ethiopia.

Abstract Since 2020, milk thistle Silybum marianum, an invasive weed species, has been widely observed in urban green spaces and roadsides in Addis Ababa city, Ethiopia. To plan future management activities, this study aimed to determine the current distribution status of the weed in urban green areas of Addis Ababa city. Weed surveys were conducted across 42 urban green sites located in Yeka, Lemi Kura, Bole, Nifas Silk-Lafto, Kolfie Keraniyo, Akaky Kality, and Gullele sub-cities during the main rainy season from June to September 2023. Urban green areas were selected using purposive sampling techniques. Field observations confirmed that Silybum marianum can invade and colonize a wide range of habitats and is highly competitive, posing a threat to important native plant species. High weed density rates and dense stands of weeds were recorded in the 34 urban green areas surveyed. The survey results strongly suggest implementing fast integrated weed management options such as mowing/tilling, weeding before the plant goes to seed, cutting (stems and/or seed heads), and burning (collected plant parts and/or seed heads) into a prepared burrow to minimize the spread of the weed and its ecological impacts. The purpose of this survey study is to provide information about Silybum marianum to minimize or avoid its distribution and associated impacts by following sustainable invasive weed management programs in the city before spreading to other cities in the country.

Weed communities after decades of mineral fertilization and tillage treatments in a corn–soybean rotation

Abstract Soil fertility and disturbance can potentially modify weed dynamics in a corn–soybean rotation. Knowing how added mineral fertilizers and tillage influence weed populations in the long term can provide insight into weed community shifts, which may affect future weed management requirements. The first objective of this study was to evaluate the effect of 24 to 25 years of nitrogen and phosphorus fertilization treatments and tillage (moldboard vs. no-till) on weeds (density, biomass, and composition) before and after herbicide applications in 2016/corn and 2017/soybean. The second objective was to evaluate the effect of the same treatments 6 yr after no postemergence weed management in 2022/corn. Since the last evaluation performed in 2004, weed density, richness, and diversity increased, and more annual grasses were observed under both tillage regimes. No fertilization effect was observed on any weed variables, including composition, except for increased biomass when left to grow all season after crop planting. In managed plots, the density and biomass of annuals and perennials were generally higher in no-till, and discrepancies were highest for annual grass densities before herbicide application. Weed species richness and diversity based on counts were equivalent between tillage regimes, but total biomass was distributed between more species in no-till. Higher weed densities and concurrent weed biomass, observed in no-till, reduced crop yields in 2016/soybean only. The combination of low crop diversity and low use of residual herbicides during the trial potentially led to the observed species shifts and increased weed density.

The Manual, Chemical, Cultural, and Integrated Weed Management in Soybean Production

A field experiment was conducted at Sher-e-Bangla Agricultural University, Dhaka, from December 2021 to April 2022 to study the effect of weed management practices in soybean (Glycine max L.). The experiment was laid out in a Randomized three-Complete Block Design (RCBD) with twelve weed management treatments- no weeding (Control), two hand weeding (at 15 and 30 DAS), pre-emergence herbicide (Herbilin 33% EC @ 400 ml ha-1), post-emergence herbicide Irish EC @ 1200 ml ha-1, pre + post-emergence herbicide, pre-emergence + 1 hand weeding {40 days after sowing (DAS)}, post-emergence herbicide + 1 hand weeding (40 DAS), pre + post-emergence herbicide + 1 hand weeding(40 DAS), straw mulching, intercrop with Amaranthus dubius, and Zea mays, and weed-free. The experimental result showed among seven different weed species found, Cyperus rotundus was the most prevalent weed, with the highest weed density (123 and 128.67 m-2) and relative weed emergence (43.16 and 38.79 %) in the control plot at 30 and 60 DAS. The treatment pre + post-emergence herbicide + 1 hand weeding (40 DAS) showed the longest pod length (4.16 cm) and number of seeds pod-1 (3.89). The weed-free treatment resulted in the highest 1000-seed weight (111.00 g), seed yield (1.86 t ha-1), stover yield (2.16 t ha-1), biological yield (4.03t ha-1), and harvest index (46.35 %). However, the highest benefit-cost ratio (2.85) was obtained under post-emergence herbicide (Irish EC) treatment. Therefore, applying Irish EC was the best broad-spectrum effective herbicide to manage the various weed floras in soybeans for profit. SAARC J. Agric., 21(2): 195-206 (2023)

To Study the Effect of Integrated Weed Management Practices on Weeds Parameters of Transplanted Rice in Chhattisgarh Plains

The present experiment entitled “To study the effect of integrated weed management practices on weeds parameters of transplanted rice in Chhattisgarh plains” was studied during the 2022, kharif season at Agricultural Research Farm BTC, CARS, Bilaspur, Chhattisgarh. A randomized block design with ten treatments and three replications was used. Treatment T5 (untreated control) had the highest weed density and dry weight measurements, whereas treatment T6 (weed-free) had the lowest.The weed index was lowest in T6 (weed-free). The stage with the highest percentage of weed control efficiency was T6 (Weed-Free), then T10 (Chlorimuron ethyl 10% WP + Metsulfuron methyl 10% WP @ 0.06g ha-1 (20 DAT) + mechanical weeding (20 &amp; 40 DAT) by Ambika paddy weeder at all stages.

Above Ground Emergence and Floristic Composition of Weeds in Relation to Tillage and Weed Management Practices in Maize and Cowpea

Background: Weeds are one of the most important elements influencing crop productivity. Tillage practices have a significant effect on the weed seed bank and the appearance of weeds, both of which have a direct impact on farm productivity. Different tillage strategies based on ploughing depth, as well as weed control practices, change the dynamics of weed seeds in the soil. This research will aid in the development of integrated weed control methods by investigating the interaction between tillage and weed management practices. Methods: Field trials were carried out in two seasons, Summer and Kharif 2022, using a split-plot design with three tillage methods and four weed management practices. The treatments were replicated three times. Result: Among the different tillage treatments Mouldboard plough fb Cultivator fb Rotovator recorded the lowest weed density. With respect to weed management methods, pre- and post-emergence herbicide application and hand weeding at 20 and 40 DAS recorded the lower weed density. Interaction effects of tillage and weed management practices resulted in lower weed density in Mouldboard plough fb Cultivator fb Rotovator with herbicide application and Mouldboard plough fb Cultivator fb Rotovator with hand weeding. Highest weed density was recorded under Cultivator fb Rotovator in unweeded control. With respect to relative density, among the broad-leaved weeds (BLW) Trianthema portulacastrum and Dactyloctenium aegyptium in grasses dominated among the weed species in 30 and 60 DAS respectively. From the present study it was concluded that the Mouldboard plough fb Cultivator fb Rotovator with hand weeding twice or herbicide application reduces the weed emergence from the soil weed seed bank.

Occurrence of Faba Bean Diseases and Determinants of Faba Bean Gall (Physoderma sp.) Epidemics in Ethiopia.

Physoderma fungal species cause faba bean gall (FBG) which devastates faba bean (Vicia faba L.) in the Ethiopian highlands. In three regions (Amahara, Oromia, and Tigray), the relative importance, distribution, intensity, and association with factors affecting FBG damage were assessed for the 2019 (283 fields) and 2020 (716 fields) main cropping seasons. A logistic regression model was used to associate biophysical factors with FBG incidence and severity. Amhara region has the highest prevalence of FBG (95.7%), followed by Tigray (83.3%), and the Oromia region (54%). Maximum FBG incidence (78.1%) and severity (32.8%) were recorded from Amhara and Tigray areas, respectively. The chocolate spot was most prevalent in West Shewa, Finfinne Special Zone, and North Shewa of the Oromia region. Ascochyta blight was found prevalent in North Shewa, West Shewa, Southwest Shewa of Oromia, and the South Gondar of Amhara. Faba bean rust was detected in all zones except for the South Gonder and North Shewa, and root rot disease was detected in all zones except South Gonder, South Wollo, and North Shewa of Amahara. Crop growth stage, cropping system, altitude, weed density, and fungicide, were all found to affect the incidence and severity of the FBG. Podding and maturity stage, mono-cropping, altitude (&gt;2,400), high weed density, and non-fungicide were found associated with increased disease intensities. However, crop rotation, low weed infestation, and fungicide usage were identified as potential management options to reduce FBG disease.

Weed infestation and productivity of wheat crop sown in various cropping systems under conventional and conservation tillage.

Climate change, pest infestation, and soil degradation are significantly reducing wheat (Triticum aestivum L.) yield. Wheat is cultivated in rice-wheat and cotton-wheat cropping systems and escalating global population is exerting substantial pressure on the efficiency of these systems. Conservation tillage and crop rotation could help in lowering soil degradation and pest infestation, and improving wheat yield. This three-year study evaluated soil properties, weed infestation and wheat yield under various tillage and cropping systems. Six different cropping systems, i.e., cotton-wheat, sorghum-wheat, mungbean-wheat, rice-wheat, sunflower-wheat, and fallow-wheat (control) and three tillage systems, i.e., conventional tillage (CT), zero-tillage (ZT) and minimum tillage (MT) were included in the study. The individual and interactive effects of tillage and cropping systems significantly affected soil properties, weed infestation and yield of wheat crop. Overall, CT resulted in lower soil bulk density and higher porosity, while ZT behaved oppositely at all locations in this regard. Similarly, mungbean-wheat cropping system resulted in lower bulk density and higher porosity and nitrogen (N) contents, while fallow-wheat cropping system resulted in higher bulk density, and lower soil porosity and N contents. Similarly, ZT and CT resulted in higher and lower weed infestation, respectively. Likewise, lower and higher weed density and biomass were recorded in wheat-sorghum and wheat-fallow cropping systems, respectively at all locations. In the same way higher number of productive tillers, number of grains per spike, 1000-grain weight, grain yield, and economic returns of wheat crop were recorded for CT, whereas ZT resulted in lower values of these traits. Regarding interactions, wheat-mungbean cropping system with CT resulted in lower bulk density and higher porosity and N contents, whereas wheat-fallow system with ZT behaved oppositely at all locations in this regard. Similarly, higher and lower values for yield-related traits and economic returns of wheat crop were noted for mungbean-wheat cropping system under CT and fallow-wheat and sorghum-wheat cropping systems under ZT, respectively. It is concluded that the mungbean-wheat cropping system improved wheat productivity and soil health and sorghum-wheat cropping system could lower weed infestation. Therefore, these cropping systems can be practiced to lower weed infestation and improve wheat yield and economic returns.

Distribution of Chickpea (Cicer arietinum L.) Ascochyta blight (Didymella rabiei) and analyses of factors affecting disease epidemics in Central Ethiopia

Ascochyta blight (caused by Didymella rabiei) is one of the most important diseases affecting chickpea production and productivity. The distribution, incidence and severity of the disease, and the association of agronomic practices and environmental factors on the intensity of the disease mainly remained undermined. Chickpea field surveys were conducted in two main chickpea growing regions of central Ethiopia during the 2020 and 2021 main cropping seasons to determine the distribution and importance of Ascochyta blight and analyse its association with biophysical factors. A total of 366 chickpea fields were surveyed in five zones, and 76.6% of the fields were infected with Ascochyta blight. The results revealed that the overall mean prevalence and incidence of the disease ranged from 46.66 to 100%. Ascochyta blight in the infected fields had a mean severity index of 40.17%. The mean disease incidence was higher in fields at altitudes below 2129 m.a.s.l (39.2%) than the mean incidence of fields at higher altitudes. Using logistic regression analysis, the independent variables—zone, altitude, cropping season, seed source, cultivar type, variety, planting pattern, and plant density—were shown to have significant effects on the severity index (P < 0.001). High weed density, growth stage, planting time, crop rotation, Fusarium wilt, pod borer, aphid spp., and dry root rot were also significantly associated (P < 0.05) with Ascochyta blight epidemics. The highest severity (SI = 60.3%) was obtained in Arsi Zone, and the lowest in South West Shewa Zone (SI = 32.1%). The results of this survey indicate that planting chickpea in the middle of the main rainy season, proper weed management, planting improved varieties, and crop rotation should be practiced to reduce the negative impact of the disease until effective resistant chickpea varieties are developed. Furthermore, it is recommended that effective and feasible integrated management options need to be developed against the disease to boost the production and productivity of the crop.

Establishing forbs for pollinators in agricultural landscapes of the Great Plains, U.S.A.

Pollinator insects are declining, partly because grasslands containing forbs they feed on have been converted to cropland. This conversion is prevalent in the Great Plains, home to several imperiled pollinators and 40% of U.S. honeybees. Over 1.0 million hectares of former cropland have been seeded with forbs that could benefit Great Plains pollinators, but success of these seeding efforts is unclear. We quantified forb abundances and factors regulating these abundances in 120 crop fields seeded to forbs and grasses by managers in the Great Plains (Colorado and Montana). Our data indicated a need to improve forb establishment. Two to five growing seasons after seeding, seeded forb cover was &lt;10% in most fields, and no seeded forbs were observed in 23% of fields. Our data also indicated ways to benefit forbs. High grass seed rates and high weed densities shortly after seeding reduced forb cover at the end of the study. Past studies indicate certain post‐emergence herbicides sometimes benefit seeded forbs, and we recommend further research in this domain. Instead of beneficial herbicides applied after seeding, managers sometimes applied risky herbicides before seeding that appeared to persist in soil and reduce forb establishment. Seed rates were too low to maximize forb abundances, and much money was wasted buying seeds of species that did not establish. We identified several species with relatively high establishment probabilities that will support most pollinators. For now, these species should be seeded at high rates. Lower rates could become sufficient if effective weed control is implemented.

Growth, Physiology, Weed Abundance and Yield in Rice (&lt;em&gt;Oryza Sativa&lt;/em&gt; L.) Under Three Nutrient Input Systems in the Dry Zone of Sri Lanka

A field experiment was conducted to compare the growth, physiology, weed abundance and yield in rice under three input systems; organic, conventional and integrated, during the 2019 <em>Yala </em>season as the second season of a long-term cropping systems trial. The design used a Randomized Complete Block Design (RCBD), with six (6) replicates for each treatment. The rice variety used in the experiment was Bg 300 and three treatments were based on three input systems such as T1 – Conventional input system (100% Department of Agriculture (DOA) inorganic fertilizer recommendation), T2 – Integrated system (50% of Department of Agriculture (DOA) inorganic fertilizer recommendation+50% of the rate of compost added to organic input system) and T3 – Organic system (No inorganic fertilizers and only compost with the rate of 10000 kg ha -1). At the panicle initiation and harvesting stages, there was a (p&lt;0.05) significant difference (in rice shoot biomass across the three input systems, with the organic system having the lowest values compared to the other two. At panicle initiation, 50 % heading, and harvesting phases, a significant difference (p&lt;0.05) in plant height was noted among the three input systems, with the organic system showing the lowest values at all stages. The organic system had the highest weed count at all three crop stages and no significant difference between integrated and conventional systems. The three input systems had a significant difference in final grain yield at 14 percent moisture. At 14% moisture, there was no difference in final grain yield between conventional and reduced systems (4.85 and 4.67 tonnes/ha) with the organic system having the lowest value (2.74 tonnes/ha). Overall results indicate that reducing inorganic fertilizers by 50% with the combination of organic manure as in the integrated system gives similar final grain yields as the conventional system of new improved varieties like Bg 300 in high potential areas like Anuradhapura. Also, organic systems can show low crop growth and yields due to inadequate nutrient supply through organic materials and high weed density during the first year of transition.

Winter cover crops and dynamics of weeds in agricultural systems of the Argentine Rolling Pampas

The aim of this study was to determine if different mixtures and monocultures of cover crops (CC) reduce aerial dry matter, number and diversity of autumn-winter weeds. Two experiments with different CC species were implanted in the INTA Pergamino Agricultural Experimental Station (Pergamino, Buenos Aires, Argentina, 33° 51´ S, 60° 34´W) in 2018 and 2019. The species used were: Avena sativa, Triticosecale and Vicia villosa. Mixtures and monocultures of CC were used, in different proportions and densities, and were compared with a chemical fallow. Two cuts of CC were made aboveground at tillering and milk grain stages (Z 2.5 and 7.3, respectively) to obtain aerial dry matter of CC (ADMcc, g.m−2), ADM of weeds (ADMw, g.m−2) and number of weeds (weeds.m−2). Moreover, weed species were identified and Shannon diversity and evenness indices and effective specific richness were calculated. In 2018, the highest ADMcc was recorded in Avena sativa at Z 2.5 as well as the highest weed density. At Z 7.3, the highest ADMcc was recorded in Avena sativa, Triticosecale and their mixture. At that stage, the highest ADMw was recorded in the chemical fallow. In 2019, the 3:1 Avena sativa/Vicia villosa mixture showed the highest ADMcc and diversity of weed community showed non-significant differences from the chemical fallow at Z 2.5. There were non-significant differences in ADM among CC and diversity of weed community in the CC was practically null at Z 7.3. At both stages, the highest number of weeds and ADMw was observed at chemical fallow, whereas in CC, non-significant differences were detected. The results obtained indicate that CC reduce the number, ADMw and diversity of the weed community, regardless of the mixtures used.

Influence of Weed Control Techniques on Weeds, Yield, and Economics of Dry Direct-seeded-Drip-irrigated Rice under Philippine Conditions

The use of herbicides in combination with hand weeding has been shown to be effective against a variety of weeds in irrigated and rainfed wet direct-seeded rice in the Philippines. In the case of dry direct-seeded-drip-irrigated rice; however, these aspects are not known. A study was conducted to determine the influence of two weed control techniques on weeds, yield, and economics of dry direct-seeded-drip-irrigated rice under Philippine conditions. Four treatments – [T1] unweeded; [T2] application of pre-emergence herbicide using pretilachlor, followed by two times hand weeding; [T3] application of post-emergence herbicide using bispyribac-sodium, followed by two times hand weeding; and [T4] weed-free using the sequential application of pre- and post- emergence herbicides followed by six times hand weeding – were tested and arranged in RCBD with three repetitions. T1 has the highest weed density and biomass with lower grain yield (901.8 kg ha–1) but no net income. T2 and T3 had lower weed biomass than T1 but could not be compared with T4, where no weed density and biomass were recorded at 15, 30, and 45 DAS (days after seeding) in both dry and wet seasons. Grain yields at T2 (3,794.4 kg ha–1) were not significantly different from T3 (4,341.3 kg ha–1) except when compared with T4 (5,7245 kg ha–1). Net income in T2 was higher by PHP 20,575.1 over T1 and T3 by PHP 9,831.4 over T2. T4 had the highest grain yield among all treatments and achieved an advantage of PHP 45,272.1, 24,697.0, and 14,865.7 over T1, T2, and T3, respectively, in terms of net income. Herbicide application followed by hand weeding reduced weed growth and improved rice yield and net income. The combination of pre- and post-emergence herbicides followed by six times hand weeding was much more effective at suppressing weeds and achieving higher grain yield and net income.

Irrigation Scheduling and Weed Management: A Sustainable Approach for Managing Broomrape and Other Weeds in Tomato Crop

Broomrape (Orobanche cernua L.) is an obligate root parasitic weed that significantly reduces the qualitative and yield attributes of tomatoes globally. The efficient management of broomrape is challenging because of its complicated parasitic nature. Field trials were conducted to assess the influence of various irrigation scheduling and weed control strategies on broomrape, weed presence, and tomato productivity. The experiment was conducted with a randomized complete block design (RCBD) with a split-plot arrangement and was replicated three times. Three irrigation intervals (3, 6, and 9 days) were assigned to the main block, while sub-blocks including treatments and year were taken as the source of variance (year × irrigation timing × treatments). The experiment comprised sixteen treatments, including transparent polythene, black polythene, weedy check (Control), sole weeding of broomrape only, weeding of all weeds, weeding except broomrape, humic acid 25 kg ha−1+ copper oxychloride in single and split doses, copper oxychloride (1.5 kg a.i ha−1 in single and split doses), ammonium sulphate 200 kg ha−1 in single and split doses, copper sulfate (2 kg ha−1 in single/split doses), and glyphosate 48 SL (1.5 kg a.i ha−1) and pendimethalin 33 EC (1.44 kg a.i ha−1). The results revealed that among the various irrigation intervals, the highest broomrape intensity (4.34 plant−1) was observed with a9-day irrigation interval. Similarly, the highest weed density (35 m−2) resulted in a3-day irrigation interval. Furthermore, irrigation at a 6-day interval increased the plant height by 11%, fruit yield tons ha−1 by 24.9 %, and produced the highest cost/benefit ratio (CBR) of (1:4). Black polythene, transparent polythene, and pendimethalin reduced the weed density by 92%, 89%, and 84%;weed dry biomass by 97%, 95%, and 91%; and broomrape intensity by 67%, 77%, and 28%. Conversely, the plant height increased by 24%, 23%, and 23.6%; and fruit yield by 286%, 270%, and 191%; and had the highest CBR of 1:5, 1:4, and 1:4, respectively, as compared to the weedy check. Consequently, an increase in irrigation frequency increases other weed densities and decreases the broomrape intensity plant−1 of tomato. Therefore, black polythene could be recommended in a severely broomrape-infested field. Moreover, irrigation at 6-day intervals combined with pendimethalin and ammonium sulfate fertilizers revealed the lowest incidence of broomrape and other weeds and produced an economic yield.