Abstract Since its introduction into Ethiopia during 1970s, Prosopis juliflora, became an environmental issue in areas where it was first introduced to combat desertification. This review paper was aimed at reviewing some adverse effects of the plant on socioeconomic, environmental and biodiversity with its control practices in the eastern Ethiopia. Contrary to its purpose of introduction, this plant has been found to be highly invasive and, it imposed adverse effects on the native plant species. The plant is declared as an invader which has put impacts on socioeconomic, environment, and biodiversity of the eastern region of Ethiopia especially afar region and Dire Dawa; which became alarm for pastoralists, development agents, scientists, and policy makers. Though cultural practices such as burning and cutting were mainly practiced, the invasion could not be stopped.

Abstract A limiting factor in valerian production is weed interference so, the crop protection from weed is essential. Field experiments were conducted for two consecutive seasons (2014-2015) to evaluate different weed control methods on growth, yield, and oil quality of valerian in Iran. The experimental design was a randomized block with 7 treatment and 4 replicates. Treatments included untreated control, manual weeding, barley straw, sorghum straw, wheat, black plastic and post-emergence oxadiargyl. The lowest density and dry weight of weeds was related to the manual weeding treatment. Result showed that the maximum growth parameters of valerian were obtained from manual weeding treatment followed by black plastic, barely straw and sorghum straw reflecting superior weed control. Essential oil analyses indicated that bornyl acetate, valerenal, camphene and α-pinene were the most abundant constituents. These components on average represent 27.7, 14.7, 4.1 and 2.2% of the oils that were extracted from plant, respectively. Bornyl acetate, valerenal and camphene contents did not vary with the various studied treatments although there was a trend toward higher in manual weeding treatment. Overall finding of current experiments suggested that barely straw and sorghum straw are potential substitutes for manual weeding and black plastic mulch for weed control in valerian.

Abstract Weed increase reduces crop yields, while chemicals applied to control weed have adverse environmental impacts. Thermal control has a less negative effect on the environment and health of consumers compared to chemical methods. After construction, the flame weeding efficiency of this method for eliminating near-row weed at three speeds of drive and three different amounts of liquid gas consumption was evaluated. The flame weeding manufactured and connected to the back of an offset tractor and navigation system. The flame weeding had a sidewall that prevented the flame from directly touching crop plants inside the row. Flame weeding were performed based on split-plots and on randomized complete block design with two factors of movement speed at three levels of low (3 km/h), medium (4 km/h) and high (5 km/h) and liquid gas consumption does at three levels of low (3 km/h), medium (5 km/h) and high (7 km/h). The results in both sugar beet and corn showed the interactive effects of two speed and amount consumption factors on each other. Weed control rates had varied considerably with flame treatment at different speeds and doses of liquid gas. With the increasing speed and decreasing liquid gas, the average weed control ratio decreased from 0.86 to 0.1. needle leaf weed control ratio in all cases is less than broadleaf weed. As the advance rate and the amount of liquid gas consumed decreases, the proportion of weed control declines substantially, and vice versa. This trend showed an inverse correlation between speed and liquid gas consumption factors.

Abstract The aim of the present work is to evaluate the herbicidal activity allelopathic extracts of sorghum plants (Sorghum bicolor L.) on wheat and accompanied weeds namely wild oat and canary grass under local conditions in Egypt. The biocidal activity of the aqueous and methanolic extracts of sorghum was compared with two of the most common herbicides used on wheat i.e. diclofop-methyl and clodinafop-propargyl. Application of the tested materials was carried out by using three concentrations of sorghum extracts (5, 10 and 20%) and the recommended dose of each diclofop-methyl (750 ml/fed) and clodinafop-propargyl (140 gm/fed) under laboratory, green house and semi field conditions. The herbicidal and phytotoxic effects of both biochemical agents and conventional herbicides were carried out by measuring germination percentage, seedling shoots and root length, dry weight, chlorophyll content, plant height, plant numbers, spike length and spike weight of the treated wheat. The obtained results indicated that there is no adverse effect of the tested extracts against the measured parameters of productivity and yield of wheat. At the same time promising herbicidal activity of aqueous and methanolic extracts of sorghum was revealed against wild oat and canary grass in particular with aqueous extract of sorghum at concentration of 20%.

Abstract Parthenium hysterophorus L. is a notorious weed, which significantly reduce yield and quality of crops and causes several problems to human health. In, present study an attempt was made to understand the economic value, and survival nature of Parthenium through deep transcriptome analysis. Transcriptome analysis of leaf and root tissue of P. hysterophorus had resulted 7,832,143 reads in case of leaves, and 9,646,830 reads in case of roots sample with longest read length of 300 and 298 nucleotides, respectively. A total of 35,719 contigs were produced with an average length of 548bp after an assembly in all two samples. The Blastn of the above generated contigs with 61,901 sequences of P. argentatum resulted in the identification of 25,947 novel contigs specific to P. hysterophorus. The Kyoto Encyclopedia of Genes and Genomes pathway based analysis showed the expression of genes associated with pathways pertaining to biosynthesis of Glucosinolate, Amino acids, and Aminobenzoate degradation etc. The expression pattern of genes like Artemisinic aldehyde Delta (11(13)) reductase, Codeine O-demethylase, Taraxerol synthase, and Curculin-2 related to biosynthetic of therapeutic importance pathways was also evidenced. Further, the heavy metal accumulator property of P. hysterophorus was also studied. Expression analysis of heavy metal transporters such as ferrous ion transport protein B, and zinc transporter in roots was also validated with its heavy metal transport activity. This investigation provides new insights for functional studies of P. hysterophorus genes involved in biosynthesis of therapeutically important secondary metabolites, and other possible uses such as raw material for rubber industry.

Abstract An inventory of cultural control practices is undertaken by considering each practice for its biological selectivity with respect to weeds. Descriptions of cultural practices in the literature are often brief. Some recent syntheses neglect knowledge from older publications. Disagreement concerning the delimitation of these practices is common. Clarification of the knowledge base concerning the cultural management of field flora is required for "sustainable agriculture". The selectivity most often mentioned for each practice is limited to a few examples of taxa in a geographically limited area and is rarely considered in the light of general mechanisms of action on biological cycles. The controversial distinction made by many authors between preventive and curative methods is unnecessary. Each practice listed is presented with its biological target. On the scale of a single cultural cycle, thirty practices are compared. Each target tends to have a specific biological descriptor. Most of the practice target pairs have the disadvantage of having an extreme state opposed to that of the target. Crop rotations are described as successions between non-competitive crops or practices that encourage certain weeds on the one hand and cleaning crops or practices on the other. The latter mainly target diaspores that have a lifespan inferior to the planned cleaning duration. The allelopathic after-effects show three mechanisms. In temperate climates, rotations may be complex with respect to the diversity of crop and weed phenologies. Combinations of cultural interventions must take into account the mechanisms involved, particularly because some results could cancel each other out.

Abstract The objective of this work is to evaluate the allelopathic effects of the aqueous and methanolic extract of rice straw (Oryza sativa L.) on wheat (Triticum aestivum L.) and wheat weeds, including wild oat (Avena fatual L.) andcanary grass (phalaris minor). Three concentrations (5, 10 and 20%) of each aqueous and methanolic extract as well as the recommended dose of chemical herbicide clodinafop propargyl (140 g/ fed) and diclofop-methyl (750 ml/fed) were used on the tested plants as a post-emergence treatments. Response of the treated plants were measured by using 7 parameters includes: germination %, seedling shoots and root length, dry weight, chlorophyll content, plant height, plant number and spike length and weight of treated wheat. Data of each parameter were discussed separately. Generally, treatments with higher concentrations (20% rice straw aqueous and methanolic extract) showed negative effects on wheat weeds at the same time cause increasing the wheat productivity. However, rice straw methanolic extracts showed suppressive effect on wheat seed. Comparing the efficacy of the straw extract with the tested conventional herbicides, the obtained data showed that clodinafop propargyl and diclofop-methyl were the most effective against the time tested weeds as it severely reduced the weed population and other tested parameters.

Abstract A study was conducted to determine the effect of climate gradient and previous crop on weed flora structure in pearl millet crop. Thus, floristic surveys were carried out during 2016 and 2017 crop years on station in Sahelian, Sudano-sahelian and Sudanian zones of Senegal. The results revealed that flora consisted of 81 species distributed in 59 genera and 19 families. Higher number of species were recorded in Sudanian zone (Kolda and Séfa) with respectively 61 and 45 species and the lowest number of species were found at Vélingara in Sudano-sahelian zone (28 species) and Sinthiou Malème in sahelian zone (28 species). According to previously crop, the higher number of species was registered in previous fallow (64 species) followed by previous pearl millet (57 species). In previous mucuna and peanut, flora is 14 percent lower than species recorded in previous fallow. Spectrum analysis indicated that the flora is largely dominated by therophytes, which includes 81.5% of the recorded species. It’s presence in pearl millet field was higher in Sahelian zone (93%) followed by Sudano-sahelian zone (89%) and Sudanian zone (Kolda and Séfa) with respectively 80 and 84% of recorded species. Domination of therophytes is more accurate in plot with previous fallow (86%) followed by previous millet (82%), previous peanut (81%) and previous mucuna (79%). Also, it was observed a decreasing of perennial species from Sudanian to Sahelian zone.

Abstract Field experiments were conducted to identify the effective tank-mix combinations of HPPD (p-hydroxyphenylpyruvate dioxygenase) herbicides (Mesotrione, tembotrione and topramezone) with atrazine for post-emergence grass and broadleaf weeds control in maize crop during the three kharif seasons of 2013 to 2015. The dominant weeds infested the experimental plots were crow footgrass{Dactyloctenium aegyptium (L.) Willd.}; large crabgrass, Digitaria sanguinalis (L.) Scop; barnyard grass, Echinochloa crus-galli (L.) Beauv.; Digera arvensis Forsk. and Horse purslane(Trianthema portulacastrum L.). All the three HPPD herbicides showed good crop safety and among them, for grass weed control, mesotrione 120 g ha^-1 applied alone was inferior to topramezone 50 g ha^-1 and tembotrione 120 g ha^-1 applications. However, reduced doses of the HPPD herbicide (mesotrione 90 g or topramezone 37.5 g or tembotrione 90 g ha^-1) with atrazine 900 g ha^-1 as post-emergent tank-mixture gave better weed control and maize yield than their solo applications. The uncontrolled weed competition reduced the maize yields by 31.5 to 68.5%. Overall, topramezone + atrazine provided comparable or superior control of annual grass and broad-leaf weeds than mesotrione + atrazine or tembotrione + atrazine. Post applied (15-18 days after sowing) atrazine 1000 g ha^-1 was better to pre-emergence atrazine in weed control and producing maize yield. In another field study, replacement of maize with puddle rice completely reduced the Johnsongrass {Sorghum halepense (L.) Pers.} density and therefore, in areas having its infestation, rice can be an alternative to contain its problem. The synergistic interactions between HPPD-inhibiting herbicides, and atrazine, were also observed against three grass weeds in pot experimentation as higher weed control achieved than what was expected from Colby’s equation. The results show that tank-mixture of topramezone or tembotrione with atrazine can be effectively used for diverse weed flora control in maize.

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.