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This study investigates the inhibitory effects of Diaporthe sp. isolate EC010 extract on barnyardgrass (Echinochloa crus-galli) seed germination and growth. Application of sequential extraction techniques to Diaporthe sp. mycelium resulted in partial separation of the phytotoxic compounds. The ethyl acetate (EtOAc) fraction most greatly reduced seed germination (81.01%), root length (89.18%), and shoot length (84.74%) compared to the control. Chemical characterization using gas chromatography-mass spectrometry revealed major constituents of linoleic acid, butyl ester (9.69%), hexadecanoic acid (7.99%), and 14-pentadecenoic acid (7.86%). With regard to physiological and biochemical indexes, treated seeds exhibited lower imbibition, significantly decreased α-amylase (EC 3.2.1.1) activity (p <0.05), and increased accumulation of malondialdehyde (85.52%) and hydrogen peroxide (141.10%). Moreover, activity of the antioxidant enzymes superoxide dismutase (EC 1.15.1.1) and guaiacol peroxidase (EC 1.11.1.7) was upregulated (67.24 and 61.62%, respectively), while catalase (EC 1.11.1.6) activity was downregulated (-33.75%). The inference is that an imbalance in ROS levels combined with reduced antioxidant potential drives the gradual accumulation of oxidative damage in seed cells and consequent loss of seed viability. All told, these results confirm the Diaporthe extract to induce oxidative stress and inhibit antioxidant enzymes. This study clearly demonstrates the oxidative damage associated with Diaporthe allelochemicals. [ABSTRACT FROM AUTHOR]

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This study investigates the inhibitory effects of Diaporthe sp. isolate EC010 extract on barnyardgrass (Echinochloa crus-galli) seed germination and growth. Application of sequential extraction techniques to Diaporthe sp. mycelium resulted in partial separation of the phytotoxic compounds. The ethyl acetate (EtOAc) fraction most greatly reduced seed germination (81.01%), root length (89.18%), and shoot length (84.74%) compared to the control. Chemical characterization using gas chromatography-mass spectrometry revealed major constituents of linoleic acid, butyl ester (9.69%), hexadecanoic acid (7.99%), and 14-pentadecenoic acid (7.86%). With regard to physiological and biochemical indexes, treated seeds exhibited lower imbibition, significantly decreased α-amylase (EC 3.2.1.1) activity (p

IntroductionRice rationing is one of the ways to increase rice production without expanding the cultivation area. Currently, the average ratoon rice production fa unit area is very low, and one of the most important reasons is the decrease in yield due to the lack of control or improfa control of weeds. Weed control in ratoon rice is difficult for various reasons such as lack of water and big weed seedlings after harvesting the main crop of rice. In rice ratooning, unlike the main rice cultivation, in which several methods such as puddling, flooding, manual weeding and herbicides are used to manage weeds, the control of weeds is limited to foliar herbicides. Currently, there is not much information about ratoon rice weed control, therefore, investigating the efficiency of different herbicides in this field can lead to the introduction of high-efficiency herbicides in controlling weeds and thus improving the yield of ratoon rice fa unit area. Materials and Methods This research was carried out during the 2017 and 2018 crop seasons in the research fields of Rice Research Institute of Iran in Gilan and Mazandaran provinces. The studied herbicide treatments were; Doses of 25, 38, 50, and 63 g/ha, a.i of bispyribac sodium SC 10% (Chif), doses of 31, 47, and 63 g/ha, a.i of bispyribac sodium SC 12.5% (Vejin), 40 g/ha, a.i of bispyribac sodium SC 40% (Clean-weed), 25 g/ha, a.i of bispyribac sodium SC 10% (Nomini), 1398 g/ha, a.i of propanil + benzosulfuronmethyl DF 46.6% (Stamdox), 1150 g/ha, a.i of bentazon + MTHPA SL 46% (Bazagran), 45 g/ha, a.i of Triaphamon + Ethoxysulfuron WG 30% (Council) and weedy control. The rice cultivar used in the main cultivation in both locations was Hashemi. The main rice seedlings were transplanted in 20 x 20 cm planting distance. Visual assessment of weeds control and weed biomass measurement were done in two stages. The evaluation of phytotoxicity and growth disorders of herbicides on rice plant and the effectiveness of them in weed control was carried out based on the European standard system. Results and DiscussionThe results showed that bispyribac sodium herbicide, up to 63 g/ha, a.i, did not lead to visible phytotoxicity symptoms in ratoon rice. In Gilan province, Four weeks after herbicide application, the biomass of barnyardgrass (Echinochloa crus galli) in the weedy check was 35 g/m2. The range of barnyardgrass biomass varied from 19 g/m2 for Stamdax to 32 g/m2 for Bazagaran herbicide. Six weeks after spraying, Vejin herbicide (47 and 63 g/ha, a.i), Clean-weed and Nomini had the lowest amount of barnyardgrass biomass with 26, 20, 23 and 26 g/m2, respectively. Which were 71, 78, 75 and 71 facent reduction compared to the weedy check (91 g/m2). The highest efficiency in the sedge (Schoenoplectus maritimus) control was also recorded in the same four treatments. Four weeks after herbicide application, weedy check had the highest weed biomass fa unit area with 53 g, although it did not have a significant difference with Stamdax, Clean-weed, Nomini and Vejin herbicide recommended dose. Bazagaran and Council had the lowest amount of sedge biomass with 30 and 32 g/m2, respectively. Sedge biomass reached 150 g/m2 six weeks after herbicide application in the weedy check. Twice the recommended dose of Vejin herbicide with 21 g/m2 had the highest efficiency (86%) in sedge control compared to the weedy check. Although there was no significant difference in this respect with the Nomini, Cleanweed and 150% of Vejin herbicide recommended dose. The lowest efficiency with 35 and 37% belonged to Chif and Stamdax herbicide treatments, respectively. The highest paddy yield with 1683 kg/ha was observed in Clean-weed herbicide treatment, which was 237% increase compared to the weedy check control (710 kg/ha). In Mazandaran province, two herbicides, Stamdax and Bazagaran, were the most effective in reducing weed biomass with 90% and 87%, respectively. This was while the highest paddy yield was observed in Clean-weed and Nomini herbicide treatments (2180 and 2210 k kg/ha, respectively). Conclusion This study demonstrated that bispyribac-sodium herbicide effectively controlled weeds in rice ratooning without causing any visible signs of phytotoxicity to the rice plants. This positive outcome led to a significant increase in grain yield. Among the different formulations of this herbicide, Nomini (25 g/ha, a.i) and Cleanweed (40 g/ha, a.i) had the highest efficiency in weed control and as a result, increasing the paddy yield. Therefore, bispyribac sodium herbicide can be used as a suitable replacement for current herbicides in rice ratooning. [ABSTRACT FROM AUTHOR]

Barnyardgrass (Echinochloa crus-galli) is one of the most troublesome weeds in irrigated rice cultivation and has increasingly impacted rainfed crops due to the emergence of herbicide-resistant populations. Understanding its germination dynamics is crucial for developing and implementing effective management strategies. Additionally, since barnyardgrass research relies on growing plants from seeds, its dormancy characteristics are of particular interest. The present study aimed to evaluate the influence of postharvest age on barnyardgrass seed germination and the effectiveness of different dormancy-breaking methods in susceptible and herbicide-resistant populations. Germination rate (G), germination speed index (GSI), and seed viability, assessed using the topographic tetrazolium test, were measured in seed lots with four different postharvest ages: two years, one year, two months, and one day postharvest. The seeds were subjected to 15 dormancy-breaking methods, including temperature variation and the use of solutions containing H2SO4, KNO3, and GA3. Seeds that were one or two years old showed germination rates exceeding 90%, regardless of the method used. In contrast, seeds aged two months or one day postharvest only germinated when exposed to 40°C for seven days, with G values of 25.2% and 5.9%, respectively. Both herbicide-susceptible and resistant barnyardgrass populations exhibited similar dormancy levels and responses to dormancy-breaking methods. The results indicate that newly harvested seeds have high dormancy levels, and specific methods are only partially effective in overcoming barnyardgrass seed dormancy.

This paper focuses on the weed species Echinochloa crus-galli, commonly known as barnyardgrass, which is a persistent threat to crop yield and quality, especially in maize (Zea mays) cultivation. It is one of the most problematic weeds in agricultural fields due to its aggressive growth, adaptability to different environmental conditions and prolific seed production. The incidence of Echinochloa crus-galli in maize fields has increased in recent years. This study aims to provide a comprehensive understanding of the characteristics and behavior of Echinochloa crus-galli, and to suggest effective measures to control it. This research on sweetcorn was conducted from 1992 to 2019 at the Research and Education Center Gorzyń, Złotniki branch, which belongs to the Poznań University of Life Sciences. The evaluation of weed infestation was carried out in experiments focusing on chemical weed control in maize. The experiments were designed as a one-factor randomised block design with four field replications. The condition and the degree of weed infestation (number of weeds and fresh weight of weeds) in the control plots was assessed on an annual basis at the end of June and in July. The aim of the study was to evaluate the dynamic changes in the status and extent of barnyardgrass (Echinochloa crus-galli) infestation in maize grown after various other crops in the Wielkopolska region, with a focus on the weather conditions. The study found that barnyardgrass was most likely to occur when maize was sown after winter wheat in a dry and warm year, and least likely when maize was grown in rotation after winter wheat in a cold year with average rainfall. The proportion of barnyardgrass weed mass in the total weed mass was significantly lower after winter rye than after winter wheat, winter oilseed rape and winter triticale. Further research into the biology and ecology of barnyardgrass is key to effectively controlling this weed and safeguarding sweetcorn yields. [ABSTRACT FROM AUTHOR]

Increase in the concentration of atmospheric greenhouse gases significantly contributes to global warming, representing a substantial challenge for crop production. The study was conducted to determine the growth competition between rice (Oryza sativa) and barnyardgrass (Echinochloa oryzicola) under (i) different cropping patterns and (ii) elevated air temperatures in phytotrons under field condition, at two plant densities (4 and 16 plants per pot). Rice and barnyardgrass were planted with varying cropping patterns (rice: barnyardgrass mixture proportions); 100:0, 75:25, 50:50, 25:75 and 0:100. Air temperatures were maintained in phytotrons as follows: Ambient–A (Control), A +0.8 °C, A +1.9 °C and A +3.4 °C. Plant attributes such as plant height, number of effective tillers, shoot dry weight and grain yield of rice were recorded in this study in the rice/barnyardgrass mixture proportions in the order of 100:0 > 75:25 > 50:50 > 25:75. The highest rice grain yield (37.7 g/pot) was recorded in the monoculture (100:0 rice/barnyardgrass) under ambient temperature, whereas the lowest rice grain yield (0.3 g/pot) was recorded at the 25:75 rice/barnyardgrass mixture proportion under ambient +3.4 °C. The increase in temperature had a significant impact on growth, number of tillers and shoot dry weight of both rice and barnyardgrass plants and followed the order of ambient +3.4 °C > ambient +1.9 °C > ambient +0.8 °C > ambient. However, higher temperature negatively affected the yield of rice and resulted in a substantial decrease in the grain yield. Barnyardgrass showed the highest plant characteristics when grown alongside rice compared to the growth in monoculture. This indicates that barnyardgrass was highly competitive when grown under interspecific competition compared to an intraspecific competition. In contrast, rice grew better in monoculture than in mixture with barnyardgrass. [ABSTRACT FROM AUTHOR]

Historically, herbicides were used for Echinochloa spp control in California rice production which led to the selection of herbicide-resistant biotypes. Field surveys were conducted across the seven major rice-growing counties in 2020 and Echinochloa spp samples including barnyardgrass (Echinochloa crus-galli (L.) P.Beauv.), junglerice (Echinochloa colona (L.) Link), late watergrass (Echinochloa oryzicola (Vasinger) Vasinger) and coast cockspur (Echinochloa walteri (Pursh) Heller) were collected. Greenhouse experiments were carried out to determine their suspected resistance to common preemergence and postemergence rice herbicides used in California in Fall and Winter of 2021. A total of 62 and 63 samples were characterized for suspected resistance to four preemergence granular and three postemergence foliar-applied herbicides, respectively. When granular herbicides were evaluated, samples suspected of resistance in Winter were a subset of samples that were suspected of resistance in Fall. Results indicate >90% of Echinochloa spp samples were resistant to thiobencarb, benzobicyclon + halosulfuron and penoxsulam when combined across species and counties. Cross-resistance between benzobicyclon + halosulfuron and penoxsulam was observed in >90% of the samples when combined across species and counties. Suspected clomazone resistance was observed in <75% of the samples when combined across species and counties. Suspected resistance to cyhalofop and propanil was observed in <50% of the samples when averaged across both runs. Multiple-resistance to foliar herbicides ranged from 48-60% of the samples across species and experimental runs. These results indicate the necessity for rotating herbicides during alternate cropping seasons and emphasizing integrating non-chemical strategies for Echinochloa spp control in California rice production. [ABSTRACT FROM AUTHOR]

BACKGROUND: Recently, suspected cyhalofop‐butyl‐resistant populations of allohexaploid weed Echinochloa crus‐galli var. crus‐galli were discovered in rice fields in Aichi Prefecture, Japan. Analyzing the target‐site ACCase genes of cyhalofop‐butyl helps understand the resistance mechanism. However, in E. crus‐galli, the presence of multiple ACCase genes and the lack of detailed gene investigations have complicated the analysis of target‐site genes. Therefore, in this study, we characterized the herbicide response of E. crus‐galli lines and thoroughly characterized the ACCase genes, including the evaluation of gene mutations in the ACCase genes of each line. RESULT: Four suspected resistant lines collected from Aichi Prefecture showed varying degrees of resistance to cyhalofop‐butyl and other FOP‐class ACCase inhibitors but were sensitive to herbicides with other modes of action. Through genomic analysis, six ACCase loci were identified in the E. crus‐galli genome. We renamed each gene based on its syntenic relationship with other ACCase genes in the Poaceae species. RNA‐sequencing analysis revealed that all ACCase genes, except the pseudogenized copy ACCase2A, were transcribed at a similar level in the shoots of E. crus‐galli. Mutations known to confer resistance to FOP‐class herbicides, that is W1999C, W2027C/S and I2041N, were found in all resistant lines in either ACCase1A, ACCase1B or ACCase2C. CONCLUSION: In this study, we found that the E. crus‐galli lines were resistant exclusively to ACCase‐inhibiting herbicides, with a target‐site resistance mutation in the ACCase gene. Characterization of ACCase loci in E. crus‐galli provides a basis for further research on ACCase herbicide resistance in Echinochloa spp. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The use of allelopathic rice varieties has recently been increasing due to their safety and sustainability in weed management. This study aims to investigate the allelopathic effects of rice varieties developed through N-methyl-N-nitrosourea (MNU) mutation on the growth of lettuce and barnyard grass, as well as to establish the relationship between grain quality and the allelopathy of rice plants. Rice straw, husk, and grain samples of rice varieties K1, K2, K3 and K4 were collected and extracted with methanol. The methanol extracts were investigated for antioxidants, total phenolic content (TPC), total flavonoid content (TFC) and the presence of momilactones A (MA) and B (MB). They were subjected to high-performed liquid chromatography (HPLC) coupled with a UV detector and tested for their allelopathic potential. MA and MB were quantified using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS). The results revealed that mutant varieties exhibited higher antioxidants and TPC in both the grain and straw. Additionally, the mutant varieties increased the presence of MA and MB in the straw and husk. The straw exhibited stronger inhibitory effects compared to the husk. The straw samples from mutant rice varieties exhibited stronger inhibition towards lettuce (Lactuca sativa L.) and barnyard grass (Echinochloa crus-galli L.). Both the straw and husk strongly inhibited seed germination, shoot length and root length in barnyardgrass compared to lettuce. The inhibition was more pronounced in root growth than shoot growth. Rice varieties with higher allelochemical contents in their straw and husk exhibited stronger allelopathic effects. These findings suggest that rice varieties developed through the MNU mutation exhibited higher allelopathic activity compared to their wild-type cultivars. Therefore, the MNU mutation shows promise for breeding allelopathic rice varieties, which can help reduce the reliance on synthetic herbicides for weed control. [ABSTRACT FROM AUTHOR]

Ukraine is one of the world’s guarantors of food security and has the potential to further increase agricultural production. However, the vast majority of herbicides used on crops are acetolactate synthase (ALS) inhibitors, which poses a threat of herbicide-resistant weed species. The emergence and spread of herbicide-resistant weed biotypes can significantly increase the cost of growing crops to the point of loss of profitability. Herbicide resistance in barnyardgrass (Echinochloa crus-galli var. crus-galli) has been studied in long-term field and greenhouse experiments. Resistance of E. crus-galli to the ALS herbicide triazolopyrimidine derivative ‒ penoxsulam was identified. Expressed resistance was observed in weed plants grown from seeds collected under production conditions in Kherson region in 2015–2016 and 2020–2021. Cross resistance was observed for imidazolinone and sulfonylurea derivatives. It should be noted that the level of cross resistance to ALS herbicides was slightly higher for plants derived from weed seeds harvested in 2020–2021 compared to those harvested in 2015–2016. The introduction of a herbicidal composition of a herbicide mixture ‒ an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD) (an enzyme in plants in the chain of carotenoid synthesis) ‒ mesotrione with an ALS-inhibitor (nicosulfuron) allowed effective control of the weed, which indicates the absence of multiple resistance to herbicides ‒ inhibitors of carotenoid synthesis. The high efficiency of E. crus-galli control was established by the application of herbicides ‒ inhibitors of fatty acid synthesis (graminicides). The highest level of efficiency in the experiments was observed with the application of fluazifop-butyl and somewhat less ‒ with pinoxaden. A tendency to reduce phytotoxicity to barnyardgrass from the south of Ukraine was observed with the introduction of tepraloxydim and quizalofop-ethyl. A lower level of phytotoxicity of fenoxaprop-p-ethyl on E. crus-galli should be noted compared to the effect of pinoxaden. No multiple resistance was observed with glyphosate (5-enolpyruvylshikimate-3-phosphate synthase inhibitor) and reglone (photosystem I inhibitor), allowing control of vegetative weeds at the beginning and end of the growing season. It has been established that monocot weed species have significantly increased their presence and harmfulness in agrophytocenoses in Ukraine and in the world since the 1950s with the widespread introduction of selective dicotyledonous species control with aryloxyphenoxyacetic, propionic and benzoic acid derivatives. This trend has been maintained until recently ‒ barnyardgrass is one of the dominant weed species in modern agrophytocenoses of Ukraine. Therefore, the identification of the ALS-resistant biotype of barnyardgrass complicates weed control in the following crops in rotations in the southern regions of the country: in maize crops with cross resistance to nicosulfuron, in sunflower ‒ to imidazolinones (imazamox, imazapyr), and also makes it impossible to use penoxsulam in rice production. Traditionally, the use of synthetic auxins, phenoxyacetic acid derivatives, etc. is used to control ALS-resistance. However, in Kherson region of Ukraine, already in the third year of application of rinskor (florpyrauxifen-benzyl), some weed plants were found on rice fields affected by ALS-resistant barnyardgrass, which recovered after the use of synthetic auxin. Therefore, the control of ALS-resistance (penoxsulam, etc.) in E. crus-galli with the application florpyrauxifen-benzyl in the Kherson region of Ukraine is already limited. An obvious and economically feasible preventive measure against the emergence of resistant weed biotypes is the implementation of GAP (Good Agricultural Practice, FAO) approaches: in particular, the use of high quality seeds without weed impurities, increasing the proportion of agrotechnical weed control measures, restoring and expanding crop rotations with mandatory rotation of herbicides with different modes of action, introducing dicotyledonous/leguminous crops into rotations, and using herbicides with different modes of action in crops separately or in mixtures. At the same time, agrotechnical measures and the preservation of biodiversity in agrophytocenoses should be the main factor in controlling resistance in weeds. The use of herbicides and their mixtures with different modes of action is of secondary importance. The identification of highly damaging ALS-resistant E. crus-galli in southern Ukraine indicates the insufficient effectiveness of weed control exclusively with herbicides with a single mechanism of action and requires a significant revision of the principles of crop rotation and ways of weed control in the country to maintain high levels of profitability and productivity of agrophytocenoses. Solving this problem is urgent for the preservation of Ukraine's potential as one of the guarantors of global food security.

Historically, herbicides were used for Echinochloa spp control in California rice production which led to the selection of herbicide-resistant biotypes. Field surveys were conducted across the seven major rice-growing counties in 2020 and Echinochloa spp samples including barnyardgrass (Echinochloa crus-galli (L.) P.Beauv.), junglerice (Echinochloa colona (L.) Link), late watergrass (Echinochloa oryzicola (Vasinger) Vasinger) and coast cockspur (Echinochloa walteri (Pursh) Heller) were collected. Greenhouse experiments were carried out to determine their suspected resistance to common preemergence and postemergence rice herbicides used in California in Fall and Winter of 2021. A total of 62 and 63 samples were characterized for suspected resistance to four preemergence granular and three postemergence foliar-applied herbicides, respectively. When granular herbicides were evaluated, samples suspected of resistance in Winter were a subset of samples that were suspected of resistance in Fall. Results indicate >90% of Echinochloa spp samples were resistant to thiobencarb, benzobicyclon + halosulfuron and penoxsulam when combined across species and counties. Cross-resistance between benzobicyclon + halosulfuron and penoxsulam was observed in >90% of the samples when combined across species and counties. Suspected clomazone resistance was observed in

The genus Echinochloa consists of about 33 species worldwide; some of these are weeds that are very difficult to control in Argentina, and only E. colona was reported as resistant to glyphosate. The objective of this work is to determine if one or more populations of E. colona, E. crus-galli, E. oryzoides, and E. chacoensis are resistant to or less susceptible to glyphosate. Between 2015 and 2017, seeds of different Echinochloa populations were collected from the provinces of Córdoba, Santa Fe, Buenos Aires, and Entre Ríos, all from fields with a history of at least 10 consecutive years of glyphosate application and complaints from farmers due to failures in control. With these populations, survival, dose–response, and shikimic acid quantification tests were carried out to determine their level of susceptibility to glyphosate. The results obtained allow us to report the first worldwide case of resistance to glyphosate in populations of E. crus-galli, E. oryzoides, and E. chacoensis and expand the information on E. colona. [ABSTRACT FROM AUTHOR]

This paper focuses on the weed species Echinochloa crus-galli, commonly known as barnyardgrass, which is a persistent threat to crop yield and quality, especially in maize (Zea mays) cultivation. It is one of the most problematic weeds in agricultural fields due to its aggressive growth, adaptability to different environmental conditions and prolific seed production. The incidence of Echinochloa crus-galli in maize fields has increased in recent years. This study aims to provide a comprehensive understanding of the characteristics and behavior of Echinochloa crus-galli, and to suggest effective measures to control it. This research on sweetcorn was conducted from 1992 to 2019 at the Research and Education Center Gorzyń, Złotniki branch, which belongs to the Poznań University of Life Sciences. The evaluation of weed infestation was carried out in experiments focusing on chemical weed control in maize. The experiments were designed as a one-factor randomised block design with four field replications. The condition and the degree of weed infestation (number of weeds and fresh weight of weeds) in the control plots was assessed on an annual basis at the end of June and in July. The aim of the study was to evaluate the dynamic changes in the status and extent of barnyardgrass (Echinochloa crus-galli) infestation in maize grown after various other crops in the Wielkopolska region, with a focus on the weather conditions. The study found that barnyardgrass was most likely to occur when maize was sown after winter wheat in a dry and warm year, and least likely when maize was grown in rotation after winter wheat in a cold year with average rainfall. The proportion of barnyardgrass weed mass in the total weed mass was significantly lower after winter rye than after winter wheat, winter oilseed rape and winter triticale. Further research into the biology and ecology of barnyardgrass is key to effectively controlling this weed and safeguarding sweetcorn yields.

Increase in the concentration of atmospheric greenhouse gases significantly contributes to global warming, representing a substantial challenge for crop production. The study was conducted to determine the growth competition between rice (Oryza sativa) and barnyardgrass (Echinochloa oryzicola) under (i) different cropping patterns and (ii) elevated air temperatures in phytotrons under field condition, at two plant densities (4 and 16 plants per pot). Rice and barnyardgrass were planted with varying cropping patterns (rice: barnyardgrass mixture proportions); 100:0, 75:25, 50:50, 25:75 and 0:100. Air temperatures were maintained in phytotrons as follows: Ambient–A (Control), A +0.8 °C, A +1.9 °C and A +3.4 °C. Plant attributes such as plant height, number of effective tillers, shoot dry weight and grain yield of rice were recorded in this study in the rice/barnyardgrass mixture proportions in the order of 100:0 > 75:25 > 50:50 > 25:75. The highest rice grain yield (37.7 g/pot) was recorded in the monoculture (100:0 rice/barnyardgrass) under ambient temperature, whereas the lowest rice grain yield (0.3 g/pot) was recorded at the 25:75 rice/barnyardgrass mixture proportion under ambient +3.4 °C. The increase in temperature had a significant impact on growth, number of tillers and shoot dry weight of both rice and barnyardgrass plants and followed the order of ambient +3.4 °C > ambient +1.9 °C > ambient +0.8 °C > ambient. However, higher temperature negatively affected the yield of rice and resulted in a substantial decrease in the grain yield. Barnyardgrass showed the highest plant characteristics when grown alongside rice compared to the growth in monoculture. This indicates that barnyardgrass was highly competitive when grown under interspecific competition compared to an intraspecific competition. In contrast, rice grew better in monoculture than in mixture with barnyardgrass.

Barnyardgrass (Echinochloa crus-galli (L.) Beauv.) is one of the most troublesome weeds in transplanted and direct-seeded rice worldwide. To develop a strategy for the biocontrol of barnyardgrass, fungal isolates were recovered from barnyardgrass plants that exhibited signs of necrosis and wilt. An isolate B-48 with a high level of pathogenicity to barnyardgrass was identified after pathogenicity tests. From cultural and DNA sequence data, this strain was identified as Colletotrichum echinochloae. The inoculation of the barnyardgrass plant with C. echinochloae caused a significant reduction in fresh weight. The isolate B-48 was highly pathogenic to barnyardgrass at the three- to four-leaf stages. When inoculated at a concentration of 1 × 107 spores/mL, barnyardgrass could achieve a reduction in fresh weight of more than 50%. This strain was safe for rice and most plant species. The results of this study indicated that this strain could be a potential mycoherbicide for barnyardgrass control in paddy fields in the future. [ABSTRACT FROM AUTHOR]

Dicamba plus glyphosate (DpG) tank mixture has been widely adopted for broad-spectrum weed control. However, recent studies indicated antagonistic interactions between these herbicides. Furthermore, little is known about the effect of non-ammonium sulfate water conditioner (non-AMS WC) adjuvant on the activity of DpG tank mixture. Thus, the present study was elaborated to evaluate (1) the interaction of DpG tank mixtures combinations on barnyardgrass, and glyphosate-susceptible (GS) and -resistant (GR) horseweed control, and (2) the effect of non-ammonium sulfate water conditioner (non-AMS WC) on the interaction of those two herbicides on the aforementioned weed species. Greenhouse experiments were conducted in 2020 at the Pesticide Application Laboratory in North Platte, NE. Herbicide treatments were arranged in a two-level factorial design of six dicamba rates by six glyphosate rates for Study 1, and in a three-level factorial design of two adjuvant treatments (presence or not of non-AMS WC) by four dicamba rates by four glyphosate rates for Study 2. Both trials were conducted as randomized complete block designs with four replications and two runs. Antagonistic interactions were observed throughout DpG treatments in GS and GR horseweed. For instance, dicamba (560 g ae ha−1) and glyphosate (1260 g ae ha−1) resulted in 72% of GR horseweed biomass reduction, compared to 81% of estimated biomass reduction. For barnyardgrass, antagonistic interactions were only observed within the reduced glyphosate rates. The addition of non-AMS WC had no effect on DpG antagonism. However, it improved the barnyardgrass control by glyphosate. [ABSTRACT FROM AUTHOR]

Barnyardgrass (a monocotyledon) and yerbadetajo (a dicotyledon) are the most troublesome weeds in rice fields in China. The synthetic auxin herbicide florpyrauxifen-benzyl can effectively control both weeds. The objective of this research was to clarify modes of action of florpyrauxifen-benzyl in barnyardgrass and yerbadetajo. Our results showed that yerbadetajo was more sensitive to florpyrauxifen-benzyl than barnyardgrass: the 50% growth rate inhibition in barnyardgrass and yerbadetajo was 4.14 and 0.38 g a.i. ha−1, respectively. Florpyrauxifen-benzyl induced the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and abscisic acid (ABA) in yerbadetajo within 24 h, while in barnyardgrass, the highest production occurred at 12 h and decreased at 24 h. ACC and ABA levels in yerbadetajo at 24 h of treatment were significantly higher than those in barnyardgrass at any time. There were less differentially expressed genes related to ethylene and ABA synthesis in barnyardgrass than in yerbadetajo. There were five genes induced to increase by florpyrauxifen-benzyl in barnyardgrass and eleven genes in yerbadetajo. More ACC oxidase genes (ACO) were induced in barnyardgrass and more ACC synthesis genes (ACS) in yerbadetajo, especially three ACS3 (>30 fold). We speculated that differences in gene expression caused differences in ethylene and ABA production, leading to differences in phytotoxicity. [ABSTRACT FROM AUTHOR]

This experiment was performed to determine the appropriate dose of Cyhalofop-butyl (CB) for controlling grass weeds in transplanted rice. CB at four doses, including 50, 100, 150, and 200 g ai/ha was investigated and compared with current herbicides in rice at recommended doses. The results showed that CB 100, 150, and 200 g ai/ha significantly reduced the density and dry matter of Echinochloa crusgalli (L.) P. Beauv. and Paspalum distichum L. over the weedy check; the minimum control efficacy of CB at these doses was 73.3 and 88.3% for E. crusgalli density and dry matter reduction, respectively, and for P. distichum, it was 80% for density and dry matter reduction. Applying CB at all doses (50- 200 g/ha) showed no crop injury symptoms on rice plants. The highest grain yield was obtained by hand weeding, CB 150 g ai/ha, and Tiobencarb treatments, with 5180, 5106, and 5051 Kg/ha, respectively. CB 200 g ai/ha was on par with CB 150 g ai/ha, and there was no significant variation between CB 100 and 200 g ai/ha in rice grain production. Finally, it was found that the application of CB 100 g ai/ha is an efficient grass weed control practice for improving the rice yield.

Bipolaris eleusines was mixed with herbicides to improve the control of barnyardgrass (Echinochloa crus-galli), a noxious weed in rice fields. The compatibility of B. eleusines with herbicides was evaluated for toxic effects on spore germination and mycelium growth in vitro tests, and varied effects were observed with different chemical products. Briefly, 25 g/L penoxsulam OD plus 10% bensulfuron-methyl WP were much more compatible with B. eleusines, and there was no inhibition of spore germination but the promotion of mycelium growth of B. eleusines at all treatment rates. Under greenhouse conditions, the coefficient of the specificity of B. eleusines conidial agent was determined as 3.91, closer to the herbicidal control of 2.89, showing it is highly specific between rice and barnyardgrass. Field experiments in 2011 and 2012 showed that B. eleusines conidial agent displayed good activity on barnyardgrass, monochoria [Monochoria vaginalis (Burm.f.) Presl. Ex Kunth.], and small-flower umbrella sedge (Cyperus difformis L.) and had no negative impact on the rice plant. It also reduced the loss of rice yield when compared with the non-treated control and could make this pathogen a conidial agent for commercial bioherbicidal development in the future. [ABSTRACT FROM AUTHOR]

Botanical compounds with herbicidal activity exhibit safety, low toxicity, and low chances of herbicide resistance development in plants. They have widespread applications in green agricultural production and the development of organic agriculture. In the present study, dihydrocoumarin showed potential as a botanical herbicide, and its phenotypic characteristics and mechanism of action were studied in barnyardgrass [Echinochloa crus-galli (L.) P.Beauv.] seedlings. The results indicated that dihydrocoumarin inhibited the growth of barnyardgrass without causing significant inhibition of rice seedling growth at concentrations ranging between 0.5 and 1.0 g/L. Additionally, dihydrocoumarin treatment could cause oxidative stress in barnyardgrass, disrupt the cell membrane, and reduce the root cell activity, resulting in root cell death. Transcriptomic analyses revealed that dihydrocoumarin could inhibit barnyardgrass normal growth by affecting the signal transduction of plant hormones. The results showed significant differential expression of plant hormone signal transduction genes in barnyardgrass. Additionally, dihydrocoumarin interfered with the expression of numerous phenylpropanoid biosynthesis genes in barnyardgrass that affect the production of various vital metabolites. We speculate that the barnyardgrass growth was suppressed by the interaction among hormones and phenylpropanoid biosynthesis genes, indicating that dihydrocoumarin can be applied as a bioherbicide to control barnyardgrass growth in rice transplanting fields. [ABSTRACT FROM AUTHOR]

Echinochloa crus-galli (L.) P. Beauv is a monocotyledonous weed that seriously infests rice fields. Florpyrauxifen-benzyl, a novel synthetic auxin herbicide commercialized in China in 2018, is an herbicide for controlling E. crus-galli. However, a suspected resistant population (R) collected in 2012 showed resistance to the previously unused florpyrauxifen-benzyl. Whole-plant dose-response bioassay indicated that the R population evolved high resistance to quinclorac and florpyrauxifen-benzyl. Pretreatment with P450 inhibitors did not influence the GR 50 of E. crus-galli to florpyrauxifen-benzyl. The expression of target receptor EcAFB4 was down-regulated in the R population, leading to the reduced response to florpyrauxifen-benzyl (suppresses over-production of ethylene and ABA). We verified this resistance mechanism in the knockout OsAFB4 in Oryza sativa L. The Osafb4 mutants exhibited high resistance to florpyrauxifen-benzyl and moderate resistance to quinclorac. Furthermore, DNA methylation in the EcAFB4 promoter regulated its low expression in the R population after florpyrauxifen-benzyl treatment. In summary, the low expression of the auxin receptor EcAFB4 confers target resistance to the synthetic auxin herbicide florpyrauxifen-benzyl in the R- E. crus-galli. [Display omitted] • An Echinochloa crus-galli population evolved resistance to never-exposed florpyrauxifen-benzyl. • AFB4 is the target receptor of florpyrauxifen-benzyl in E. crus-galli. • Dysfunction of AFB4 in plants reduced their response to the herbicide and suppressed the overproduction of ethylene and ABA. • DNA methylation of the EcAFB4 promoter regulates its low expression in the R- E. crus-galli. [ABSTRACT FROM AUTHOR]

We determined the allelopathic effects of crude organic (hexane, ethyl acetate, and methanol) extracts of the cyanobacterial Spirulina platensis on barnyardgrass (Echinochloa crus-galli (L.) Beauv.) and Chinese amaranth (Amaranthus tricolor L.). The crude ethyl acetate extract showed the highest inhibitory activity and was subsequently fractionated by column chromatography into 23 fractions based on thin-layer chromatography band pattern similarities. Four concentrations (2000, 1000, 500, and 250 ppm) of each fraction were tested for their allelopathic activity. Fractions E6 and E13 exhibited the most significant inhibitory effects against Chinese amaranth. The constituents of the highly active E6F3-E6F5 fractions determined by GC-MS, chromatography, and spectroscopy included the fatty acids, γ-linolenic acid 15, oleic acid 12, and predominantly palmitic acid 7; minor constituents included 2-ethyl-3-methylmaleimide 9 and C11 norisoprenoids (dihydroactinidiolide 10 and 4-oxo-β-ionone 13). Isolation of E13 fraction by column chromatography revealed four C13 norisoprenoids: 3-hydroxy-β-ionone 17, 3-hydroxy-5α,6α-epoxy-β-ionone 18, 3-hydroxy-5β,6β-epoxy-β-ionone 19, and loliolide 20. Their structures were elucidated by NMR spectroscopy. All six isolated norisoprenoids inhibited seed germination and seedling growth of Chinese amaranth at concentrations of 250–1000 ppm. Allelochemicals from S. platensis could be utilized in the development of novel bioactive herbicides. [ABSTRACT FROM AUTHOR]

Although barnyardgrass (Echinochloa crus-galli L.) is more competitive than rice (Oryza sativa L.) in the aboveground part, little is known about whether barnyardgrass is still competitive in recruiting endophytes and the root microbiota composition variation of rice under the barnyardgrass stress. Here, by detailed temporal characterization of root-associated microbiomes of rice plants during co-planted barnyardgrass stress and a comparison with the microbiomes of unplanted soil, we found that the bacterial community diversity of rice was dramatically higher while the fungal community richness was significantly lower than that of barnyardgrass at BBCH 45 and 57. More importantly, rice recruited more endophytic bacteria at BBCH 45 and 57, and more endophytic fungi at BBCH 17, 24, 37 to aginst the biotic stress from barnyardgrass. Principal coordinates analysis (PCoA) showed that rice and barnyardgrass had different community compositions of endophytic bacteria and fungi in roots. The PICRUSt predictive analysis indicated that majority of metabolic pathways of bacteria were overrepresented in barnyardgrass. However, eleven pathways were significantly presented in rice. In addition, rice and barnyardgrass harbored different fungal trophic modes using FUNGuild analysis. A negative correlation between bacteria and fungi in rice and barnyardgrass roots was found via network analysis. Actinobacteria was the vital bacteria in rice, while Proteobacteria dominated in barnyardgrass, and Ascomycota was the vital fungi in each species. These findings provided data and a theoretical basis for the in-depth understanding of the competition of barnyardgrass and endophytes and have implications relevant to weed prevention and control strategies using root microbiota. [ABSTRACT FROM AUTHOR]

Effective accumulated temperature (EAT) is a basic index to predict plant growing and development, while EATs for key stages during Echinochloa crus‐galli seed‐setting are still unclear. We collected three E. crus‐galli populations (Nanling [NL], Feidong [FD], and Sihong [SH]) from different rice fields in eastern China and conducted four sets of pot experiments in a greenhouse. Plants of the three populations sown on May 9–12, averagely reproduced 484–671 mature seeds per plant; showed a duration of 67–76 days from sowing to heading, with an average EAT of 1,156–1,274°C; showed a duration of 90–94 days from sowing to seeds starting maturation in plant individuals with average EATs about 1,571–1,647°C; and showed a maturation stage lasting for 14–36 days. Significant negative correlations (p <.01) were found between the period of collecting day after seed maturation and the number or 1,000‐seed weight of mature seeds collected on the day, in each set of experiment. Compared with NL individuals sown on May 9, NL individuals sown on April 10 needed significantly higher EATs for periods from sowing to seed maturation, and from heading to seed maturation. According to logistic regressions, duration days needed for 50% of seeds to mature were 93–122 days after sowing, with EATs of 1,625–1893°C for these E. crus‐galli populations. This study revealed EATs for E. crus‐galli seed‐setting, which suggested time windows for panicle‐removing control of E. crus‐galli in rice fields. [ABSTRACT FROM AUTHOR]

[Objectives]Exserohilum monoceras is one of the important pathogenic fungi of Echinochloa crusgalli（L.）Beauv in biological control. In this study, we used ultraviolet light to mutagenize and screen out a mutant strain of E.monoceras that was highly pathogenic to barnyardgrass. [Methods]Mutagenic strains by UV mutagenesis were obtained and the spore production, the pathogenicity of the detached leaves and the disease index of the barnyardgrass plants were detected, and the mutagenic strains that were highly pathogenic to barnyardgrass were screened out; molecular identification and biological characteristics of the highly pathogenic strains were screened out, and their safety were investigated. The study on the biological characteristics of mutants was performed, such as, the conidial production and pathogenicity of the mutagenesis strain, colony growth, spore germination rate, anti-ultraviolet ability thermal tolerances, and the indoor safety of the mutagenic strain to main crops by using spore suspension. [Results]The best mutation time was 25 minutes according to the mortality of the strains treated with different UV irradiation time; by detecting the spore yield, pathogenicity of leaves in vitro and disease index of barnyardgrass in vivo,four mutant strains with high virulence were screened; the genomic DNA of four mutant strains were extracted, and sequencing and comparative analysis showed that the sequence similarity of the four strains was 98% with that of Echinochloa crusgalli（L.）. The results showed that the original strain and the UV-induced mutants only slightly infected sorghum, and sorghum returned to normal after a period of time. But it was safe for the other seven crops. [Conclusions]The optimum time for UV mutagenesis of Exserohilum monoceras was 25 minutes. The mutants X27-UV148,X27-UV48,X27-UV45 and X27-UV286 were high virulence strains, which provided excellent new materials for biological control. UV mutagenesis also improved the ability of Exserohilum monoceras to resist UV,high temperature and low temperature. [ABSTRACT FROM AUTHOR]

Weed competition in southern Brazil is one of the main limiting factors for Oryza sativa L. (flooded rice) yield. Echinochloa spp. (barnyardgrass) occurs at a high frequency. Although the potential for weed interference in this cereal is well known, there is little information available about the impact of nutrient competition on rice. Thus, this study aimed to evaluate the relationship between the increase of the barnyardgrass population and the development and nutrition of flooded rice plants at different stages of development. The treatments consisted of growing populations of barnyardgrass competing with the crop from stage V4, which were: 0, 1, 6, 13, 100 and 200 plants · m−2. The experimental design was randomized blocks with two replications, and the experimental units were plots 1.53 m wide by 5 m long. Plant biomass, nutrient uptake and loss of productivity were determined with three replications. An increase in the barnyardgrass population reduced the dry mass of rice leaves and stems, regardless of the evaluation period and the vegetative or reproductive period. Barnyardgrass plants had a significant impact on the reduced grain yield of a flooded rice crop, mainly due to high nutrient competitiveness, especially N in the vegetative period and K in the reproductive period. Barnyardgrass caused a loss of yield by unit · m−2 of 1.13%. The competition for N between rice and barnyardgrass plants was higher in the vegetative period, while for K, Ca and Mg the highest competition occurred in the reproductive period.

Hühnerhirse (Echinochloa crus-galli) gewinnt als Ungras im Maisanbau zunehmend an Bedeutung. Einseitiger Einsatz von ALS-Inhibitoren erzeugt einen Selektionsdruck, der zu vermehrtem Auftreten von Resistenzen führt. Häufig handelt es sich um Target-Site-Resistenzen (TSR) mit Punktmutationen an den Positionen Ala-122, Pro- 197 oder Trp-574 des ALS-Gens. Dieses liegt in der hexaploiden Hühnerhirse in drei homologen Varianten vor. Gängige PCR-Verfahren ermöglichen nur eine gemeinsame Analyse aller Genvarianten, wodurch ein großer Teil des Informationsgehalts verloren geht. Für eine fundierte Aussage müssen die Genvarianten getrennt analysiert werden. Ein methodischer Ansatz war die allel-spezifische PCR. Hierfür wurden DNA-Polymorphismen zwischen den drei ALS-Genvarianten genutzt, um diese separat bei Position 574 hochspezifisch zu amplifizieren und zu sequenzieren. Die schwierige Struktur und geringe Polymorphismen verhinderten den Einsatz der allelspezifischen PCR an den Positionen 122 und 197. Hier wurden die drei Genvarianten gemeinsam amplifiziert und anschließend in einem mehrstufigen Ansatz mit Restriktionsenzymen spezifisch verdaut. Nach Separation, Aufreinigung und Reamplifikation der Fragmente wurden die einzelnen Genvarianten durch Pyrosequenzierung analysiert. So konnten an Position Ala-122 in allen ALS-Homologen heterozygote Mutationen nachgewiesen werden, bei Pro-197 und Trp-574 dagegen heterozygote bzw. homozygote Mutationen nur bei ALS3. Durch die Etablierung dieser Methoden können nun Resistenzmuster in Populationen von Echinochloa crus-galli detaillierter untersucht und wichtige Daten zu deren Ausbreitungsdynamik gewonnen werden.

An online survey to better understand current weed management practices and concerns in Arkansas rice was distributed in the fall of 2020. A total of 123 respondents from across the Arkansas rice growing region returned the survey covering a total of 236,414 rice hectares, representing about 40% of the planted Arkansas rice hectares in 2020. The most problematic weeds were Echinochloa crus-galli (L.) P. Beauv. (ECG), Cyperus spp., and Oryza sativa L. (weedy rice), respectively, in flooded rice, and ECG, Amaranthus palmeri S. Wats., and Cyperus spp., respectively, in furrow-irrigated rice. Most respondents (78%) reported high concern with herbicide-resistant weeds, and crop rotation (>74%) was the most common strategy listed to control and mitigate the development of herbicide-resistant weeds. A chi-square test of homogeneity showed that strategies implemented to control herbicide-resistant weeds and mitigate the evolution of herbicide-resistant weeds were not dependent on occupation type (farmer, consultant, or industry rep) nor on years of involvement in rice production. Respondents failed to control ECG 44% of the time with their first postemergence herbicide. After initial herbicide failure, 53% of respondents stated two additional herbicide applications were required to control ECG escapes while another 21% of respondents stated it was never controlled. The average ECG population at 2020 harvest was between 0.1 and 1.0 plant m−2 according to 44% of the respondents; however, 41% of respondents indicated an ECG density of 2 to 10 plants m−2 at 2020 harvest. The reported annual average cost of herbicides for rice weed control was $266.40 ha−1 with ECG accounting for 81% of the total cost. Average yield loss attributed to ECG was estimated to be 505–959 kg ha−1 (economic loss of $134–254 ha−1). However, yield loss in the most heavily infested fields was estimated to be 757–1,464 kg ha−1 (economic loss of $200–387 ha−1). Effective, non-chemical approaches to weed management were ranked as the least important current research or educational effort, indicating a paradigm shift in rice producers' weed control line of thought is needed with dwindling herbicide options due to herbicide resistance.

BACKGROUND Florpyrauxifen‐benzyl (FPB) is an arylpicolinate herbicide (Group IV) for barnyardgrass control in rice. One susceptible (Sus) and three putative FPB‐resistant (R1, R2, and R3) barnyardgrass biotypes were selected based on resistant/susceptible (R/S) ratios obtained from dose–response tests and used to investigate the potential resistance mechanisms. RESULTS: Based on visual control results, the R/S ratios of barnyardgrass biotypes R1, R2, and R3 were 60‐, 33‐, and 16‐fold greater than the Sus standard, respectively. Sequencing results of TIR1 and AFB genes in the tested barnyardgrass revealed no difference between Sus and R barnyardgrass biotypes. Absorption of [14C]‐FPB in Sus barnyardgrass increased over time and reached 90%, which was >10 percentage points greater than that in R biotypes. The [14C]‐FPB absorption in all R barnyardgrass equilibrated after 48 h. For both Sus and R barnyardgrass, most [14C]‐FPB absorbed was present in the treated leaf (79.8–88.8%), followed by untreated aboveground (9.5–18.6%) and belowground tissues (1.3–2.2%). No differences in translocation were observed. Differences between Sus and R barnyardgrass biotypes were found for FPB metabolism. Production of the active metabolite, florpyrauxifen‐acid, was greater in Sus barnyardgrass (21.5–52.1%) than in R barnyardgrass (5.5–34.9%). CONCLUSION: In conclusion, reductions in FPB absorption and florpyrauxifen‐acid production may contribute to the inability to control barnyardgrass with FPB. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Barnyardgrass (Echinochloa crus-galli (L.) Beauv.) is one of the most troublesome weeds in transplanted and direct-seeded rice worldwide. To develop a strategy for the biocontrol of barnyardgrass, fungal isolates were recovered from barnyardgrass plants that exhibited signs of necrosis and wilt. An isolate B-48 with a high level of pathogenicity to barnyardgrass was identified after pathogenicity tests. From cultural and DNA sequence data, this strain was identified as Colletotrichum echinochloae. The inoculation of the barnyardgrass plant with C. echinochloae caused a significant reduction in fresh weight. The isolate B-48 was highly pathogenic to barnyardgrass at the three- to four-leaf stages. When inoculated at a concentration of 1 × 107 spores/mL, barnyardgrass could achieve a reduction in fresh weight of more than 50%. This strain was safe for rice and most plant species. The results of this study indicated that this strain could be a potential mycoherbicide for barnyardgrass control in paddy fields in the future.

Dicamba plus glyphosate (DpG) tank mixture has been widely adopted for broad-spectrum weed control. However, recent studies indicated antagonistic interactions between these herbicides. Furthermore, little is known about the effect of non-ammonium sulfate water conditioner (non-AMS WC) adjuvant on the activity of DpG tank mixture. Thus, the present study was elaborated to evaluate (1) the interaction of DpG tank mixtures combinations on barnyardgrass, and glyphosate-susceptible (GS) and -resistant (GR) horseweed control, and (2) the effect of non-ammonium sulfate water conditioner (non-AMS WC) on the interaction of those two herbicides on the aforementioned weed species. Greenhouse experiments were conducted in 2020 at the Pesticide Application Laboratory in North Platte, NE. Herbicide treatments were arranged in a two-level factorial design of six dicamba rates by six glyphosate rates for Study 1, and in a three-level factorial design of two adjuvant treatments (presence or not of non-AMS WC) by four dicamba rates by four glyphosate rates for Study 2. Both trials were conducted as randomized complete block designs with four replications and two runs. Antagonistic interactions were observed throughout DpG treatments in GS and GR horseweed. For instance, dicamba (560 g ae ha−1) and glyphosate (1260 g ae ha−1) resulted in 72% of GR horseweed biomass reduction, compared to 81% of estimated biomass reduction. For barnyardgrass, antagonistic interactions were only observed within the reduced glyphosate rates. The addition of non-AMS WC had no effect on DpG antagonism. However, it improved the barnyardgrass control by glyphosate.

Brown lesions were found on leaves of the weed barnyardgrass in paddy fields in Hiroshima Prefecture in western Japan in June 2017. A fungus, isolated repeatedly from diseased plants and identified as Exserohilum oryzicola, was demonstrated to be pathogenic to barnyardgrass. The disease was diagnosed as leaf spot, reported abroad but new to Japan. In pathogenicity tests, the isolate was also pathogenic to barley, bread wheat, durum wheat, and rice but foliar symptoms were milder than on barnyardgrass; it was nonpathogenic on soybean. [ABSTRACT FROM AUTHOR]

Barnyardgrass (a monocotyledon) and yerbadetajo (a dicotyledon) are the most troublesome weeds in rice fields in China. The synthetic auxin herbicide florpyrauxifen-benzyl can effectively control both weeds. The objective of this research was to clarify modes of action of florpyrauxifen-benzyl in barnyardgrass and yerbadetajo. Our results showed that yerbadetajo was more sensitive to florpyrauxifen-benzyl than barnyardgrass: the 50% growth rate inhibition in barnyardgrass and yerbadetajo was 4.14 and 0.38 g a.i. ha−1, respectively. Florpyrauxifen-benzyl induced the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and abscisic acid (ABA) in yerbadetajo within 24 h, while in barnyardgrass, the highest production occurred at 12 h and decreased at 24 h. ACC and ABA levels in yerbadetajo at 24 h of treatment were significantly higher than those in barnyardgrass at any time. There were less differentially expressed genes related to ethylene and ABA synthesis in barnyardgrass than in yerbadetajo. There were five genes induced to increase by florpyrauxifen-benzyl in barnyardgrass and eleven genes in yerbadetajo. More ACC oxidase genes (ACO) were induced in barnyardgrass and more ACC synthesis genes (ACS) in yerbadetajo, especially three ACS3 (>30 fold). We speculated that differences in gene expression caused differences in ethylene and ABA production, leading to differences in phytotoxicity.

Bipolaris eleusines was mixed with herbicides to improve the control of barnyardgrass (Echinochloa crus-galli), a noxious weed in rice fields. The compatibility of B. eleusines with herbicides was evaluated for toxic effects on spore germination and mycelium growth in vitro tests, and varied effects were observed with different chemical products. Briefly, 25 g/L penoxsulam OD plus 10% bensulfuron-methyl WP were much more compatible with B. eleusines, and there was no inhibition of spore germination but the promotion of mycelium growth of B. eleusines at all treatment rates. Under greenhouse conditions, the coefficient of the specificity of B. eleusines conidial agent was determined as 3.91, closer to the herbicidal control of 2.89, showing it is highly specific between rice and barnyardgrass. Field experiments in 2011 and 2012 showed that B. eleusines conidial agent displayed good activity on barnyardgrass, monochoria [Monochoria vaginalis (Burm.f.) Presl. Ex Kunth.], and small-flower umbrella sedge (Cyperus difformis L.) and had no negative impact on the rice plant. It also reduced the loss of rice yield when compared with the non-treated control and could make this pathogen a conidial agent for commercial bioherbicidal development in the future.

Botanical compounds with herbicidal activity exhibit safety, low toxicity, and low chances of herbicide resistance development in plants. They have widespread applications in green agricultural production and the development of organic agriculture. In the present study, dihydrocoumarin showed potential as a botanical herbicide, and its phenotypic characteristics and mechanism of action were studied in barnyardgrass [Echinochloa crus-galli (L.) P.Beauv.] seedlings. The results indicated that dihydrocoumarin inhibited the growth of barnyardgrass without causing significant inhibition of rice seedling growth at concentrations ranging between 0.5 and 1.0 g/L. Additionally, dihydrocoumarin treatment could cause oxidative stress in barnyardgrass, disrupt the cell membrane, and reduce the root cell activity, resulting in root cell death. Transcriptomic analyses revealed that dihydrocoumarin could inhibit barnyardgrass normal growth by affecting the signal transduction of plant hormones. The results showed significant differential expression of plant hormone signal transduction genes in barnyardgrass. Additionally, dihydrocoumarin interfered with the expression of numerous phenylpropanoid biosynthesis genes in barnyardgrass that affect the production of various vital metabolites. We speculate that the barnyardgrass growth was suppressed by the interaction among hormones and phenylpropanoid biosynthesis genes, indicating that dihydrocoumarin can be applied as a bioherbicide to control barnyardgrass growth in rice transplanting fields.

Although barnyardgrass (Echinochloa crus-galli L.) is more competitive than rice (Oryza sativa L.) in the aboveground part, little is known about whether barnyardgrass is still competitive in recruiting endophytes and the root microbiota composition variation of rice under the barnyardgrass stress. Here, by detailed temporal characterization of root-associated microbiomes of rice plants during co-planted barnyardgrass stress and a comparison with the microbiomes of unplanted soil, we found that the bacterial community diversity of rice was dramatically higher while the fungal community richness was significantly lower than that of barnyardgrass at BBCH 45 and 57. More importantly, rice recruited more endophytic bacteria at BBCH 45 and 57, and more endophytic fungi at BBCH 17, 24, 37 to aginst the biotic stress from barnyardgrass. Principal coordinates analysis (PCoA) showed that rice and barnyardgrass had different community compositions of endophytic bacteria and fungi in roots. The PICRUSt predictive analysis indicated that majority of metabolic pathways of bacteria were overrepresented in barnyardgrass. However, eleven pathways were significantly presented in rice. In addition, rice and barnyardgrass harbored different fungal trophic modes using FUNGuild analysis. A negative correlation between bacteria and fungi in rice and barnyardgrass roots was found via network analysis. Actinobacteria was the vital bacteria in rice, while Proteobacteria dominated in barnyardgrass, and Ascomycota was the vital fungi in each species. These findings provided data and a theoretical basis for the in-depth understanding of the competition of barnyardgrass and endophytes and have implications relevant to weed prevention and control strategies using root microbiota.

We determined the allelopathic effects of crude organic (hexane, ethyl acetate, and methanol) extracts of the cyanobacterial Spirulina platensis on barnyardgrass (Echinochloa crus-galli (L.) Beauv.) and Chinese amaranth (Amaranthus tricolor L.). The crude ethyl acetate extract showed the highest inhibitory activity and was subsequently fractionated by column chromatography into 23 fractions based on thin-layer chromatography band pattern similarities. Four concentrations (2000, 1000, 500, and 250 ppm) of each fraction were tested for their allelopathic activity. Fractions E6 and E13 exhibited the most significant inhibitory effects against Chinese amaranth. The constituents of the highly active E6F3-E6F5 fractions determined by GC-MS, chromatography, and spectroscopy included the fatty acids, γ-linolenic acid 15, oleic acid 12, and predominantly palmitic acid 7; minor constituents included 2-ethyl-3-methylmaleimide 9 and C11 norisoprenoids (dihydroactinidiolide 10 and 4-oxo-β-ionone 13). Isolation of E13 fraction by column chromatography revealed four C13 norisoprenoids: 3-hydroxy-β-ionone 17, 3-hydroxy-5α,6α-epoxy-β-ionone 18, 3-hydroxy-5β,6β-epoxy-β-ionone 19, and loliolide 20. Their structures were elucidated by NMR spectroscopy. All six isolated norisoprenoids inhibited seed germination and seedling growth of Chinese amaranth at concentrations of 250–1000 ppm. Allelochemicals from S. platensis could be utilized in the development of novel bioactive herbicides.

Weed control in rice fields has become particularly difficult because of the increased occurrence of herbicide resistance. The objective of the study was to assess in field conditions, in Italy, if repeated applications of the same herbicides on Echinochloa spp. populations already showing an initial level of resistance would increase their level of resistance over a short time. Repeated applications of penoxsulam and cyhalofop-butyl were performed at different rates, either alone, in combination, or in sequence for one, two or three consecutive years (2010–2012) in the same plots. Confirmation of resistance was performed in greenhouse on plants derived from untreated plots and from those that survived the field treatments. Penoxsulam efficacy was lower than that obtained with cyhalofop-butyl. The average efficacy across herbicide treatments declined over time as it was 52%, 32%, and 13% at 28 days after treatments in plots treated for one, two and three years, respectively. The treatments performed in greenhouse confirmed the low herbicide efficacy observed in the field. Study results highlighted that repeated applications of ALS and ACCase inhibitor herbicides can accelerate resistance selection in Echinochloa, and even herbicide rotation, sequencing, or mixing might not be effective if applied at time intervals of insufficient length. [ABSTRACT FROM AUTHOR]

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Weed competition in southern Brazil is one of the main limiting factors for Oryza sativa L. (flooded rice) yield. Echinochloa spp. (barnyardgrass) occurs at a high frequency. Although the potential for weed interference in this cereal is well known, there is little information available about the impact of nutrient competition on rice. Thus, this study aimed to evaluate the relationship between the increase of the barnyardgrass population and the development and nutrition of flooded rice plants at different stages of development. The treatments consisted of growing populations of barnyardgrass competing with the crop from stage V4, which were: 0, 1, 6, 13, 100 and 200 plants · m-2. The experimental design was randomized blocks with two replications, and the experimental units were plots 1.53 m wide by 5 m long. Plant biomass, nutrient uptake and loss of productivity were determined with three replications. An increase in the barnyardgrass population reduced the dry mass of rice leaves and stems, regardless of the evaluation period and the vegetative or reproductive period. Barnyardgrass plants had a significant impact on the reduced grain yield of a flooded rice crop, mainly due to high nutrient competitiveness, especially N in the vegetative period and K in the reproductive period. Barnyardgrass caused a loss of yield by unit · m-2 of 1.13%. The competition for N between rice and barnyardgrass plants was higher in the vegetative period, while for K, Ca and Mg the highest competition occurred in the reproductive period. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Echinochloa crus-galli (L.) P. Beauv. is the most common monocotyledonous weed in maize crops in Croatia. Crop–weed interference is influenced by weed emergence patterns, and knowledge of the timing of weed emergence is crucial for the development of an efficient integrated weed-management program. Therefore, two-year field experiments were conducted in a maize crop sown in early May in continental Croatia to determine the emergence pattern of E. crus-galli from natural seedbank. In laboratory studies, the estimated base temperature and base water potential for the Croatian ecotype of E. crus-galli were 10.8 °C and −0.97 MPa, respectively. Then, the estimated germination parameters were compared with the values embedded in the AlertInf model from Italy (Veneto) to calibrate this hydrothermal model. The estimated hydrothermal units were around 28 for the onset (10%) and 93 for the middle (50%) emergence of E. crus-galli. Our findings showed that the AlertInf model satisfactorily simulated the emergence of E. crus-galli in maize crop in Croatia (EF = 0.97 in 2019 and 0.98 in 2020), indicating its potential use in other geographical areas

Summary: A better understanding of weed seed production is a key element for any long‐term management allowing some weeds to shed seeds. The challenge with measuring seed production in weeds is the large effort required in terms of time and labour. For the weed species Echinochloa crus‐galli, it was tested whether the number of seeds per panicle dry weight or per panicle length can be used to estimate seed production. Experiments were conducted in three maize fields in north‐eastern Germany. The effect of factors that could influence this relationship, such as the time of seedling emergence, the density of E. crus‐galli, the control intensity of other weeds, seed predation and field, was included. A few days before maize harvest, all panicles were removed and weighed, panicle length was measured, and for a subsample of 178 panicles, the number of seeds was counted manually. Panicle dry weight predicted the number of seeds per panicle better (R2 = 0.92) than did panicle length (R2 = 0.69). The other factors except for 'field' and 'seed predation' had no effect on these relationships. The relationships between seed number and panicle dry weight found in this study closely resembled those reported in an earlier study. Based on our results, we conclude that both plant traits are appropriate for the estimatation of seed production, depending on required level of precision and availablilty of resources for the evaluation of sustainable weed management strategies. [ABSTRACT FROM AUTHOR]

Few effective management strategies remain for controlling herbicide-resistant Echinochloa crus-galli (L). Beauv. In midsouthern USA rice production. Repeated use of the same herbicide site of action (SOA) is ineffective and may be overcome by targeting alternative SOAs. At relatively low risk for evolution of resistance, very-long-chain fatty acid (VLCFA)-inhibiting herbicides (WSSA Group 15) such as acetochlor are promising candidates for weed control in rice. Field experiments were conducted in 2016 and 2017 to evaluate the impact of acetochlor formulated as Warrant® on E. crus-galli control as part of a complete herbicide program in both imidazolinone- (Clearfield) and quizalofop- (Provisia) resistant rice systems. These studies were designed as a randomized complete block with a nontreated, weedy check included for comparison. In the Clearfield experiment, acetochlor at 1,050 or 1470 g ai ha−1 or clomazone at 336 g ai ha−1 was applied delayed preemergence (DPRE) 1) alone, 2) followed by imazethapyr at 70 g ai ha−1 early-postemergence (EP), or 3) followed by imazethapyr EP followed by imazethapyr pre-flood (PREFLD). Herbicide treatments were identical in the Provisia experiment, with the exception being that quizalofop at 120 g ai ha−1 was applied postemergence (POST) instead of imazethapyr. Rice injury was <15% following all DPRE applications in two of the three site-years; however, rainfall events shortly after application resulted in more severe rice injury 2 WAT in 2017, particularly following acetochlor applications (49–78%). Overall, clomazone-containing programs provided superior E. crus-galli control throughout the season and rice yielded higher in clomazone-than acetochlor-containing programs. Oftentimes, clomazone- and acetochlor-containing programs were comparable within single- and multi-pass programs; however, the success of acetochlor-containing programs was more affected by rainfall and dependent on POST herbicides. Should acetochlor be labeled for use in rice, it should be applied EP followed by sequential POST applications to provide weed control and yield comparable to standard programs used today. • Clomazone-containing programs provided superior E. crus-galli control over acetochlor programs in dry-seeded rice. • Rice yielded higher in clomazone- than acetochlor-containing programs because of early-season interference from E. crus-galli. • Acetochlor should be applied sequentially postemergence to provide weed control and rice yield comparable to standard programs. [ABSTRACT FROM AUTHOR]

Extracting allelochemicals from rice (Oryza sativa) straw and use for weed management is more sustainable than burning and reduces herbicide dependence. Water soluble compounds were extracted from shoots and roots of OM 5930, generating both a crystallized by-product and liquid extract. Crystallized product was applied to soil with pre-germinated barnyardgrass (Echinochloa crus-galli L. Beauv), red sprangletop (Leptochloa chinensis L. Nees), and grass-like fimbry (Fimbristylis miliacea L. Vahl) seeds. As little as 9.4 g per pot (1 ton ha−1 biomass) reduced survival of all species, with the order of sensitivity barnyardgrass (BG) < red sprangletop (RS) < grasslike-fimbry (GF). Increased rates or time of exposure (3 to 42 days after treatment; DAT) resulted in a stepwise reduction in seed survival. Using liquid extract, 5.33 g pot−1 (3 tons ha−1 biomass) reduced BG survival by 49.8%, while 2.67 g pot−1 reduced survival of RS and GF by 49.7 and 54.3%, respectively at 42 DAT. A rate of 8 g pot−1 reduced survival of BG seedlings by 78.3% but was lethal to RS and GF seedlings. The most abundant allelochemicals present were ergosterol peroxide, p-coumaric acid, and salicylic acid. OM 5930 rice is a promising variety for extraction of allelopathic compounds and application for extended herbicidal activity.

The search for potent, selective bioherbicides has been the focus of numerous studies for several decades. Developing an economically viable total chemical synthesis procedure has been the challenge for commercial-scale application of these nature-derived chemicals. An efficient and low-cost total synthesis of an allelopathic and antitumor N-trans-cinnamoyltyramine (NTCT) first reported in rice (Oryza sativa L.) was successfully achieved by one-step amidation from trans-cinnamic acid and tyramine. The synthesized NTCT inhibited root and hypocotyl growth of cress (Lepidium sativum L.) and barnyardgrass (Echinochloa crus-galli L.) at concentrations as low as 0.24 μM. The means of ED50 (the effective dose required for 50% plant growth inhibition) levels of the compound on cress and barnyardgrass hypocotyl and root elongations were 0.96 and 0.73 μM, respectively. Potential mechanisms underlying NTCT growth inhibition and its biosynthesis pathway were also suggested. The developed synthesis strategy could permit production of this synthesized allelochemical at a commercial scale as a bioherbicide.