Journal of Research in Weed Science

Abstract Striga hermonthica is widespread in several regions of Burkina Faso. It attacks crops of agronomic interest, causing losses ranging from 20 to 100% of grain yield in sorghum varieties. This study carried out at the weed science laboratory from October 2022 to February 2023 aims to identify sorghum varieties resistant to Striga hermonthica and local plants that inhibit or stimulate its germination. Fifteen varieties of sorghum has been evaluated for their germination stimulant capacity production using the agar gel method. The roots of two seedlings of each variety were buried in the opposite position in the agar medium containing Striga seeds. The effect of nine local plants on Striga hermonthica seeds germination has been evaluated by preparing 10% aqueous extract for each plant by macerating a mass of 10 g of powder in 100 ml of sterile distilled water. The inhibitory effect was estimated by conditioning the Striga hermonthica seeds during 14 days in each of the plant aqueous extracts and the stimulatory effect by the application of aqueous extracts on the Striga hermonthica seeds. The results revealed Rsoe 38 (MGD=0.74cm), Icsv 1049 (MGD = 0.74cm), Ouédzouré (MGD = 0.81cm), Grinkan (MGD = 0.85cm), Rsoe 15(MGD = 0.85cm) and B 35 (MGD = 0.97cm) as resistant to Striga hermonthica germination. Parkia biglobosa and Tephrosia purpurea have proved effective in inhibition while Andira inermis and Albizia zygia stimulate it. The promotion of resistant sorghum varieties and plants with inhibitory or stimulatory effects could be an important asset for the biological control of Striga hermonthica in the most infested areas.

Abstract A field experiment was undertaken to determine optimum combination of weed management practices and inter-row spacing levels for effective weed control in maize at Bako agricultural research center, Western Oromia, Ethiopia during 2018 main cropping season. The treatments included pre-emergence s-metolachlor 290 g/L + atrazine 370 g/L (1.0, 2.0 and 3.0 L ha^-1), hand pulling and hoeing 25 and 45 days after sowing (DAS) and weedy check in combination with inter-row spacing levels (65, 70, 75, and 80 cm). The experiment was laid out in a randomized complete block design with a factorial arrangement in three replications. The experimental field was infested with 22 weed species belonging to 12 families, out of which 77.3 %, 18.2 % and 4.5 % were broad leaved, grass and sedges, respectively. Weed management practices (WMP), inter-row spacing (IRS) and their interaction significantly influenced the weed density, dry weight and weed control efficiency at 25 and 70 DAS. All parameters of the crop were significantly affected by WMP and IRS. However, their interaction was non-significant except for number of ear per plant and grain yield. The highest grain yield was recorded in inter-row spacing of 65 cm treated with hand pulling and hoeing 25 and 45 DAS (10492.0 kg ha^-1). Whereas, the lowest grain yield (2237.0 kg ha^-1) was obtained from weedy check plot at 80 cm inter-row spacing. On the other hand, maize planted at 65 cm IRS in combination with 2 L ha^-1 s-metolachlor 290g/L + atrazine 370 g/L gave comparable grain yield which was statistically at par with that of hand pulling and hoeing 25 and 45 DAS and 3 L ha^-1 s-metolachlor 290g/l. + atrazine 370 g/L involving the same IRS. Hence, putting the environmental concern and scarce labor force under consideration, the use of reduced rate (2 L ha^-1) of herbicide in combination with narrower IRS would be the best option for effective weed management in maize. Furthermore, integration of narrower IRS with other weed management treatments enhance maize grain yield there by improving weed control efficiency.

Abstract Seed germination of some crops (Brassica campestris and Triticum aestivum) and weed seeds (Ageratum conyzoides, Bidens pilosa, Cyperus rotundus and Galinsoga parviflora) was studied under different environmental conditions like moisture (concentrations 3, 6, 9, 12, 15ml), temperature (5, 10, 15, 20 and 25˚C), pH (value 4, 5, 6, 7, 8 and 9) and light (normal, red, yellow, blue, green and dark color). For the crops too much lower or higher moisture was not favorable for germination and growth. Experiments under different moisture conditions showed that C. rotundus and G. parviflora do not require more moisture to germinate and grow. Seed germination of both crops enhanced insignificantly at 15 to 20˚C treatments. Seed germination of all weed seeds was insignificantly high at 10 to 15˚C. The percentage of seed germination of both crops increased significantly in normal and green light. Seed germination of A. conyzoides, C. rotundus and G. parviflora was insignificantly different in normal, red, yellow and green light. Germination of all weed seeds was completely inhibited by blue and dark light. The shoot and root length of weed A. conyzoides was found to be significantly high (P=0.05) in yellow light treatment, but in B. pilosa, it was high in red and green light. Similarly in C. rotundus, shoot and root length were high in normal light but in of G. parviflora it was high in green light treatment. Seed germination and seedling growth were higher in pH5-7 in most cases.

Abstract The use of weeds as insectary plants is an emerging management tactic by agroecologists to sustain beneficial insect species. Fallow lands have always been used by insects, and are an important part of their diet in fragmented ecosystems. Weeds provide nectar and floral resources to beneficial insects, and provide resources to keep those insects within a field in between flowering events. Using weeds as a tool in agricultural production reliant on pollination allows farmers to increase yield, end herbicide use, and increase biodiversity of both plants and insects. Native weeds expand the range of native insects from natural areas into agroecosystems, supporting insects that buffer against lapses in pollination by agricultural honey bees. Weeds also support parasitoid and predatory insects by providing nectar and pollen to adults, as well as alternative prey. This review examines the plant-insect ecological interactions supported by weeds left within a farm, and their potential role in supporting pollinators and parasitoids.

Abstract A field experiment was conducted to assess the growth, yield and profitability of wheat under different herbicides application in Kapilvastu and Rupandehi district, Nepal during winter season of 2018. The experiment was laid out in Randomized Complete Block Design (RCBD) with four treatments and five replications. The four treatments comprised of Pendimethalin 30 EC at 3.3 l ha^-1 as a pre emergence herbicide, sulfosulfuron 75 WG at 33.3 g ha^-1 as post emergence, pendimethalin 30 EC at 3.3 l ha^-1 followed by sulfosulfuron 75 WG at 33.3 g ha^-1 and weedy check (control treatment). Results revealed that application of pendimethalin 30 EC at 3.3 l ha^-1 followed by sulfosulfuron 75 WG at 33.3 g ha^-1 significantly reduced the weed population and produced higher wheat grain yield (4487 kg ha^-1). Economic analysis of different herbicides application also showed the highest net returns (NPR. 50,940 ha^-1) for application of pendimethalin followed by sulfosulfuron treatments. Among the tested herbicides, both pendimethalin and sulfosulfuron were found effective to weed management and profitable over weedy check.

Abstract In Southern Groundnut Basin of Senegal, weed management is one of the biggest challenges for improving upland rice production. This study aimed to evaluate the systematic composition and the infestation of weed species in order to promote a sustainable management in a context of biodiversity decreasing. Thus, phytosociological surveys were carried out during rainy season in upland rice fields. The results revealed that flora consisted of 62 species distributed in 47 genera and 15 families. The families with the highest species richness were Poaceae (24.2%), Fabaceae (12.9%) and Malvaceae (12.9%) which account for half of recorded species. Biological spectrum analysis showed that the flora is largely dominated by therophytes, with 95% of recorded species. Infestation diagram based on weeds abundance and frequency showed eight groups of species reflecting their degree of infestation. Among them, Digitaria horizontalis, Mariscus squarrosus, and Spermacoce stachydea belonged to major weeds and potential general weeds were potentially the most injurious against upland rice because of their high recovery and frequency.

Abstract The soluble carbohydrates play a major role in germination, growth, reproduction, defense and survival of perennial plant species reproducing with rhizomes under normal and adverse environmental conditions. The information regarding the amount of carbohydrates present in the rhizomes of such species could provide valuable insights for making decisions regarding the best time to control these species. Therefore, seasonal changes in the concentrations of soluble carbohydrates (fructose, glucose, sucrose) and their sum termed as total amount of soluble carbohydrates (TSCs) in the rhizomes of Russian knapweed were investigated during 2013-2014. The TSCs were low at sprouting and then slightly increased until mid-June (beginning of flowering). Thereafter, TSCs were slightly decreased from mid-June to minimal values in August (flowering period) (6.2 mg/g), and then gradually increased until the highest values in January (170.6 mg/g). Fructose (131.5 mg/g) was detected as the main soluble carbohydrate, followed by sucrose (98.8 mg/g) and glucose (73.1 mg/g). Keeping in view the results of current study, the best time to control Russian knapweed is flowering, where the amount of TSCs in the rhizomes is minimal. It is therefore recommended that the species should be controlled either at flowering stage or during the production of first rhizomes for its sustainable management in the country.

Abstract A field study was carried out to evaluate the efficacy of Prioxofop-Propanyl 15% WP (Markclodina) herbicide for wider weeds range in wheat crop during Rabi 2015-16. Six treatments including four herbicides treatments viz. Pendimethalin at 1.0 kg/ha, Clodinafop at 0.060 kg/ha, Markclodina at 0.060 kg/ha, Isoproturon + 2, 4-D at 1.0+0.5 kg/ha along with hand weeding twice (30 and 60 DAS) and one weedy check were used. Avena ludoviciana (34.30 %) and Phlaris minor (25.26 %) were the most dominatinggrassy weeds. New test herbicide Markclodino had better efficacy in controlling Phalaris minor, Avena fatua and Lolium temulentumas evidencedfrom significantly less number of weeds at all the stages of observations. The highest weed control efficiency (80.5 %) was recorded with post emergence application of Markclodina 0.060 kg/ha at 90 DAS. The application of markclodina at 0.06 kg/ha remaining at par with clodinofop propargyl (market sample) at 0.06 kg/ha, isoproturon + 2,4-D at 1.0 + 0.5 kg/ha produced significantly higher grain yield. The magnitude of increase in yield due to Markclodina over weedy check was 68.9 %. Field demonstrations on the performance of Markclodina under various locations showd that there was maximum 19.7 % increase in grain yield over control at distt. Hamirpur (Himachal Pradesh).

Abstract Field experiments were conducted in 2012 and 2013 at the Teaching and Research Farm of the University of Calabar, Cross River State, Nigeria to determine the effectiveness of integration of Fitsextra® (a solution containing Atrazine and Metolachlor herbicides as active ingredients), egusi melon and hand-weeding on weed management and tuber yield of cassava. The twelve treatments which involved individual and combinations of the above mentioned weed control methods were laid out in a randomized complete block design and replicated three times. Irrespective of the method adopted, weeding depressed weed density by 57.33 % and 63.99 % in 2012 and 2013, respectively and weed biomass by 81.00 % and 79.64 % within the same period compared with the unweeded check. Integration of Fitsextra with egusi melon and/or hand-weeding significantly (P<0.05) suppressed weeds more than the sole use of Fitsextra® or egusi melon. Integration of hand-weeding with Fitsextra and/or egusi melon reduced weed dry matter by 43.46, 87.25, 92.34 and 93.51 % in 2012, and by 53.20, 90.20, 94.61 and 94.56 % in 2013 compared with hand-weeding alone, Fitsextra alone, egusi melon alone and no weeding, respectively. Plots that were hand-weeded thrice and those treated with Fitsextra + hand-weeding twice significantly (P<0.05) produced the highest fresh tuber yield of 9.73 and 10.23 t/ha, respectively in 2013. No weeding reduced cassava tuber yield by 4.83 t/ha (84.89 %) on a 2-year average, compared with the weeded plots. Conclusively, the results indicated that, three hand-weeding optimized cassava tuber yield, however, the integration of Fitsextra or egusi melon can effectively replace the first hand-weeding.

Abstract The survey was conducted in the farmers’ field of Durba Chara village of Gauripur upazilla under Mymensingh district to find out the floristic composition of weeds in three crops i.e. summer rice, potato and winter rice under T. aman-potato-boro cropping pattern. Five farmers’ fields were surveyed by using a quadrat of 0.5m × 0.5m size in four spots from each field randomly. The data were summarized using frequency, field uniformity, mean field density and relative abundance. A total of 27 weed species belonging to 11 families were found in T. aman, potato and boro rice, of which 22 species were under 11 families in T. aman, 15 species under seven families in potato and 20 species were under nine families in boro rice. Echinochloa crusgalli was the most abundant weed in both potato and boro rice while in T. aman, Ludwigia hyssopifolia dominated over others. Echinochloa crusgalli and Polygonum hydropiper were common in both potato and boro rice. The other three dominant weed species i.e. Cyperus rotundus, Cynodon dactylon and Panicum distichum in potato and Eclipta alba, Cyperus difformis, Eleocharis atroperpurea in boro were completely different from each other. In T. aman, five completely different weed species i.e. Ludwigia hyssopifolia, Alternanthera sessilis, Polygonum orientale, Fimbristylis miliaceae and Hedyotis corymbosa were found dominant. Broadleaf weeds were dominant in both T. aman and boro but in potato, grasses dominated over others.