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1.
A new herbicide for sugar beet cultivation using the ALS‐inhibiting active ingredients foramsulfuron and thiencarbazone‐methyl is under approval in the EU member states. Sugar beet genotypes that are non‐sensitive to this herbicide are currently under development. Selectivity of the ALS‐inhibiting herbicide and yield response of the non‐sensitive genotypes might be relevant to meet the requirements for variety registration. To evaluate these issues, six field trials were conducted in Germany in 2013 and 2014. Classic herbicides and the ALS‐inhibitor herbicide were applied in dosages of up to fourfold the authorised (or applied for) application rates. The ALS‐inhibitor herbicide did not cause any significant phytotoxicity and had no effect on leaf area index at a single, double or fourfold dosage. By contrast, classic herbicides had significant negative effects at the single dosage. At fourfold dosage, they caused 41% phytotoxicity and reduced leaf area index by 35%. The relative yield difference between ALS‐inhibitor and classic herbicide treatments was 8.6% and 17.4% of white sugar yield at double and fourfold dosage respectively. The ALS‐inhibitor herbicide thus showed higher selectivity than the classic herbicides. In the registration process, the resulting yield advantage could balance a possible yield penalty of non‐sensitive genotypes. The introduction of a new system for weed control could improve application flexibility and control of troublesome weeds in sugar beet.  相似文献   

2.
The management of weeds in Malaysian rice fields is very much herbicide‐based. The heavy reliance on herbicide for weed control by many rice‐growers arguably eventually has led to the development and evolution of herbicide‐resistant biotypes in Malaysian rice fields over the years. The continuous use of synthetic auxin (phenoxy group) herbicides and acetohydroxyacid synthase‐inhibiting herbicides to control rice weeds was consequential in leading to the emergence and prevalence of resistant weed biotypes. This review discusses the history and confirmed cases and incidence of herbicide‐resistant weeds in Malaysian rice fields. It also reviews the Clearfield Production System and its impact on the evolution of herbicide resistance among rice weed species and biotypes. This review also emphasizes the strategies and management options for herbicide‐resistant rice field weeds within the framework of herbicide‐based integrated weed management. These include the use of optimum tillage practices, certified clean seeds, increased crop competition through high seeding rates, crop rotation, the application of multiple modes of action of herbicides in annual rotations, tank mixtures and sequential applications to enable a broad spectrum of weed control, increase the selective control of noxious weed species in a field and help to delay the resistance evolution by reducing the selection pressure that is forced on those weed populations by a specific herbicidal mode of action.  相似文献   

3.
Most herbicide applications to sugar beet (Beta vulgaris L.) are made to the whole crop area, but there is the opportunity to restrict applications to the crop row, decreasing the usage of herbicide by up to 70%. However, this would require greater use of mechanical weed control between rows. Experiments were performed in two seasons to evaluate the weed control performance of a novel, vision‐guided, inter‐row hoe in sugar beet crops grown on a peat fen soil. Hoe lateral placement was within ±30 mm. A precise hoeing and band spraying treatment was compared with overall herbicide use, and with treatments in which the herbicide applications were replaced by hand weeding to minimize competition between crop and weeds. Two hoe passes were made in each season, at crop growth stages of two and 10–12 true leaves in the first season and four and eight true leaves in the second season. Plant population density was not affected by treatment, indicating that none of the treatments caused crop plant loss. Use of the guided hoe controlled weeds better than overall spraying. Crop yields were not significantly different between treatments, indicating that weed control prevented competition with the crop in all treatments.  相似文献   

4.
Cover crops can suppress weeds within agricultural fields due to competitive and allelopathic effects. Glasshouse experiments were conducted to evaluate the relative proportions of allelopathic effects to the total weed inhibition. Six different cover crop species were combined with three weed species in the presence or absence of active carbon over a period of four weeks. Active carbon was used as an adsorbent for allelopathic substances in the soil. Our study revealed that the competition between cover crops and weeds shifted, possibly due to the minimisation of allelopathic effects by active carbon in the soil. We assume that the degree of cover crops allelopathic effects on weeds is species‐specific, both on the side of cover crops and on the weed side. The cover crops Raphanus sativus, Fagopyrum esculentum and Avena strigosa showed the highest allelopathic weed suppression with up to 28%. Additionally, Stellaria media turned out to be the most sensitive weed against allelopathic effects induced by all cover crops, except for Linum usitatissimum and Guizotia abyssinica. The knowledge about the contribution of competitive and allelopathic effects by cover crops would help to create cover crop mixtures with high weed suppressive ability.  相似文献   

5.
Two major weeds in rice in the Philippines, Sphenochlea zeylanica Gaertn. and Echinochloa crus‐galli (L.) Beauv., are controlled with chemical and cultural methods. In the 1980s, after >10 years of continuous use of 2,4‐D, S. zeylanica evolved resistance to the chemical in those rice fields that had been treated with 2,4‐D once or twice every cropping season. In the 1990s, E. crus‐galli evolved resistance to butachlor and propanil in rice monocrop areas where both herbicides were used continuously for 7–9 years. Rice farmers continue to use 2,4‐D, butachlor and propanil extensively and are often unaware of herbicide resistance or the potential for cross‐resistance, its causes or its implications. In order to control herbicide‐resistant E. crus‐galli, farmers are shifting to locally available herbicides with different modes of action, such as bispyribac, an acetolactate synthase inhibitor, and cyhalofop, an acetyl coenzyme A carboxylase inhibitor. Follow‐up manual weeding or rotary weeding after herbicide spraying, a common farmers’ practice, removes the susceptible and resistant biotypes and could help to delay or prevent the evolution of resistance. Although the resistance mechanisms of both weeds are not determined yet, they could be related to enhanced degradation that is similar to the mechanisms that are shown by the resistant biotypes in other countries.  相似文献   

6.
There is interest in more diverse weed management tactics because of evolved herbicide resistance in important weeds in many US and Canadian crop systems. While herbicide resistance in weeds is not new, the issue has become critical because of the adoption of simple, convenient and inexpensive crop systems based on genetically engineered glyphosate‐tolerant crop cultivars. Importantly, genetic engineering has not been a factor in rice and wheat, two globally important food crops. There are many tactics that help to mitigate herbicide resistance in weeds and should be widely adopted. Evolved herbicide resistance in key weeds has influenced a limited number of growers to include a more diverse suite of tactics to supplement existing herbicidal tactics. Most growers still emphasize herbicides, often to the exclusion of alternative tactics. Application of integrated pest management for weeds is better characterized as integrated weed management, and more typically integrated herbicide management. However, adoption of diverse weed management tactics is limited. Modifying herbicide use will not solve herbicide resistance in weeds, and the relief provided by different herbicide use practices is generally short‐lived at best. More diversity of tactics for weed management must be incorporated in crop systems. © 2014 Society of Chemical Industry  相似文献   

7.
Ryegrass (Lolium multiflorum Lam.) is one of the most difficult annual weeds to control in cultivation systems worldwide, especially in temperate regions. The widespread use of herbicides in the past two decades has selected resistant biotypes of ryegrass in crops in Southern Brazil. Ryegrass seeds are dormant when disseminated and germination can be staggered over time (crop‐growing season). Knowledge of the germination behavior of seeds from herbicide‐resistant plants has been little studied, but it would be very useful in integrated weed management. Thus, this study aimed to characterize the dynamics of the soil seed bank of two biotypes of L. multiflorum, one glyphosate‐resistant and the other glyphosate‐susceptible, under a no‐tillage system. The treatments were arranged in a bifactorial scheme, using seeds from biotypes (glyphosate‐resistant and glyphosate‐susceptible) with monthly periods of removal from field (one to 12 months). Seeds of each biotype were placed on the soil surface and covered with soil and straw to simulate no‐till conditions. The percentage of germinated, dormant, and dead seeds was evaluated every 30 days. The ryegrass seed bank of glyphosate‐susceptible and glyphosate‐resistant biotypes was reduced to 11 and 15% of dormant seeds, respectively, at the end of 12 months. However, there was no variation in germination, dormancy, and seed mortality between susceptible and glyphosate‐resistant ryegrass. Seeds of glyphosate‐resistant biotype and susceptible showed germination behavior with similar dynamics in the soil over a period of 12 months.  相似文献   

8.
The issue of cross‐ or multiple resistance to acetolactate synthase (ALS) inhibitors and the auxinic herbicide 2,4‐D was investigated in Papaver rhoeas L., a common and troublesome weed in winter cereals, in a broad‐scale study across four European countries. A combination of herbicide sensitivity bioassays and molecular assays targeting mutations involved in resistance was conducted on 27 populations of P. rhoeas originating from Greece (9), Italy (5), France (10) and Spain (3). Plants resistant to the field rate of 2,4‐D were observed in 25 of the 27 populations assayed, in frequencies ranging from 5% to 85%. Plants resistant to ALS‐inhibiting herbicides (sulfonylureas) were present in 24 of the 27 populations, in frequencies ranging from 4% to 100%. Plants resistant to 2,4‐D co‐occurred with plants resistant to sulfonylureas in 23 populations. In four of these, the probability of presence of plants with cross‐ or multiple resistance to 2,4‐D and sulfonylureas was higher than 0.5. ALS genotyping of plants from the field populations or of their progenies, identified ALS alleles carrying a mutation at codon Pro197 or Trp574 in 2,4‐D‐sensitive and in 2,4‐D‐resistant plants. The latter case confirmed multiple resistance to 2,4‐D and ALS inhibitors at the level of individual plants in all four countries investigated. This study is the first to identify individual plants with multiple resistance in P. rhoeas, an attribute rarely assessed in other weed species, but one with significant implications in designing chemical control strategies.  相似文献   

9.
Biofumigation from Brassica cover crops may be used to control soilborne pests and weeds. A study was conducted to understand the influence of biofumigation on key processes of annual weed population dynamics. Five combinations of Indian mustard (M) and oat (O) cover crop treatments were assessed in a 3 year field study at two locations in Québec, Canada. Treatments included four spring/fall cover crop combinations (M/M, M/O, O/M, O/O) and a weedy check control with no cover crop. Prior to mowing and incorporation of cover crops, weed identification, count and biomass measurements were recorded to evaluate the total weed density, to calculate the relative neighbour effect (RNE) and weed diversity metrics and to perform principal co‐ordinates analyses. Indian mustard cover crops had no impact on weed establishment in 2014 due to low biofumigant potential compared to the oat cover crop. In 2015 and 2016, Indian mustard isothiocyanate (ITC) production increased and weed establishment within the Indian mustard cover crop decreased. Moreover, post‐cover crop incorporation decreased the next year spring weed emergence. Allelopathic interference of Indian mustard was significant when plant tissues produced more than 600 μg of allyl‐ITC g?1. It is now possible to rationalise the use of Brassica cover crops and biofumigation for weed control with an enhanced understanding of the impact of biofumigation on key processes of weed population dynamics.  相似文献   

10.
In winter wheat in the USA, Aegilops cylindrica is one of the most troublesome weeds, while the pathogen Oculimacula spp. causes foot rot disease. Imazamox‐resistant (IR) and foot rot‐resistant (FR) wheat cultivars represent effective tools to control the weed and prevent disease infection. However, resistance allele (RA) movement between wheat and A. cylindrica facilitates the introgression process under herbicide and disease selection pressure. Field experiments using IR and FR A. cylindrica plants intermixed with susceptible plants were conducted to measure the proportion of the RAs in the progeny and RA movement with and without herbicide and disease selection. Yield components of A. cylindrica plants were determined across treatments. The herbicide RA proportion in the progeny was greater when plants were treated with the herbicide imazamox in both years. Disease RA proportion was greater with disease occurrence only in one year. Herbicide RA movement from resistant to susceptible plants was greater with herbicide than without it only in one year. Plants carrying the RAs had greater total spikelet weight and 1000‐spikelet weight compared with susceptible plants with or without selection. However, susceptible plants produced more spikelets than the resistant ones in the absence of selection. If plants within an A. cylindrica population acquire the herbicide RA, its proportion will increase each generation under selection. These findings contribute to the understanding of crop allele introgression into related species and the evolution of increased weediness, with weed management implications.  相似文献   

11.
Summary. Sugar beet are outstandingly tolerant to 3–methoxycarbonyIaminophenyl-A′-(3′-methylphenyl) carbamate phenmedipham) and the difference in susceptibility between the main weeds prevalent in beet crops and the beet themselves can be used to obtain selective weed control. The herbicide is applied post-emergence; action via the soil can be excluded as non-existent. A test with twenty-nine varieties of sugar beet and one variety of fodder beet showed no interaction between phytotoxicity and variety. No variety particularly susceptible to phenmedipham was found. Investigations on the mode of action and selectivity proved that phenmedipham is a strong inhibitor of the Hill reaction. There were no differences in the extent of inhibition of the Hill reaction in chloroplasts of a sensitive plant (mustard) as compared with a resistant species (sugar beet). Measurements of photosynthesis using infra-red absorption methods and intact plants showed that it was inhibited in both sensitive and resistant species: the degree of inhibition, however, varied according to the species. In contrast to susceptible weeds, the resistant sugar beet and Amarantus relroflexus showed recovery in assimilation, and the recovery phases were significant. It can thus be concluded that sugar beet and A. retroftexus are able to inactivate phenmedipham. Sélectivité du phenmediphame, herbicide de post-levée dans les cultures de de betteraves sucrièes  相似文献   

12.
Glyphosate is one of the most commonly used broad‐spectrum herbicides over the last 40 years. Due to the widespread adoption of glyphosate‐resistant (GR) crop technology, especially corn, cotton and soybean, several weed species have evolved resistance to this herbicide. Research was conducted to confirm and characterize the magnitude and mechanism of glyphosate resistance in two GR common ragweed ( A mbrosia artemisiifolia L.) biotypes from Mississippi, USA. A glyphosate‐susceptible (GS) biotype was included for comparison. The effective glyphosate dose to reduce the growth of the treated plants by 50% for the GR1, GR2 and GS biotypes was 0.58, 0.46 and 0.11 kg ae ha?1, respectively, indicating that the level of resistance was five and fourfold that of the GS biotype for GR1 and GR2, respectively. Studies using 14 C‐glyphosate have not indicated any difference in its absorption between the biotypes, but the GR1 and GR2 biotypes translocated more 14 C‐glyphosate, compared to the GS biotype. This difference in translocation within resistant biotypes is unique. There was no amino acid substitution at codon 106 that was detected by the 5‐enolpyruvylshikimate‐3‐phosphate synthase gene sequence analysis of the resistant and susceptible biotypes. Therefore, the mechanism of resistance to glyphosate in common ragweed biotypes from Mississippi is not related to a target site mutation or reduced absorption and/or translocation of glyphosate.  相似文献   

13.
Summary. A series of experiments was carried out in glasshouses and in fields to study the - behaviour of PEBC and its possible use for weed control in different beet crops as compared with other herbicides. The loss by volatilization of PEBC does not seem to constitute an important factor of dissipation, when the herbicide is applied on dry soil without incorporation; the herbicidal activity was even increased after an exposure of several days on the dry soil surface. The clay and organic matter content of the soil affected the activity of PEBC. In the field trials on sugar beet, fodder beet and red beet, PEBC was sprayed on dry soil before or after planting and activated by sprinkler irrigation or rainfall after 12 or 48 hr. In the pre-planting experiment, deep incorporation by disk-harrow and shallow incorporation by roller were compared with a non-incorporated treatment; the herbicidal activity of PEBG was significantly lower with deep incorporation. In two pre-emergence experiments, incorporation by rolling was compared with non-incorporation; the control of weeds susceptible to PEBC was somewhat better when the application was followed by rolling. PEBC was active against annual grasses and fairly active against Amaranthus spp. and Portulaca oleracea, which constitute the majority of the weeds infesting beet fields in Israel. Cruciferae were quite tolerant and perennial weeds were resistant to PEBC. Sugar beet, fodder beet and red beet tolerated doses of PEBC capable of satisfactory weed control. The activity of PEBC treatment lasted for 1 or 2 months. Under the specific conditions of beet cultivation in Israel, the application of PEBC before emergence, possibly followed by rolling, appears to be a promising herbicidal treatment. Untersuchungen über die Eigenschaften von PEBC (S-propyl N-Aubuty N-äthylthiolcarbamat) und dessen Eignung zur Unkrautbekämpfung in Rüben.  相似文献   

14.
T Hyvönen  S Ramula 《Weed Research》2014,54(3):245-255
Climate change is predicted to affect range expansion of harmful C4 weeds into the boreal region, given that they are able to successfully colonise both C3 and C4 crops. We studied the impact of a 3°C elevation in temperature on the establishment and maintenance of populations of two annual C4 weeds (Amaranthus retroflexus and Echinochloa crus‐galli) with and without a competing C3 (barley) or C4 (maize) crop. Data obtained from field and glasshouse experiments were modelled using a periodic matrix population model. Competition of a weed with a crop appeared to be a more important factor for limiting the maintenance of weed populations than elevation in temperature, as neither of the weed species was able to maintain populations in competition with crops. Even an increase in the frequency of warm years did not result in viable weed populations establishing. However, A. retroflexus was able to form persistent populations in competition with maize when released from competition every fifth year. Simulations parameterised from glasshouse data predicted that both weed species would persist without competition in the current climate, whereas simulations parameterised from field data suggested only A. retroflexus to be able to persist. These results demonstrate that competition affects the range expansion of arable weed species more than elevation in temperature, necessitating the inclusion of crop–weed interactions in models of range shifts as a consequence of climate change.  相似文献   

15.
G Fried  B Chauvel  X Reboud 《Weed Research》2015,55(5):514-524
Temporally repeated data sets can provide useful information about the management practices governing changes in the arable weed flora. This study aimed (i) to investigate changes in the most common weed species in winter oilseed rape crops in France between the 1970s and the 2000s and (ii) to pinpoint the main plant biological traits and associated management practices underlying the development of a specific weed flora in this crop. We compared two large‐scale surveys covering France in the 1970s and the 2000s, the later survey including several floristic samplings, on two dates, and both herbicide‐free control and treated plots. This last survey aimed to identify the species best able to maintain high densities over a growing season of oilseed rape. Since the 1970s, the frequency of two‐thirds (69%) of the 26 most common species has changed, spectacularly in some cases, with several species once considered rare becoming very common (e.g. Geranium dissectum) and, conversely, some formerly common species becoming rarer (e.g. Stellaria media). Our results indicated a general strong increase in specialist weeds of oilseed rape. Weed species success was favoured by tolerance to oilseed rape herbicides and germination synchronous with the crop. The proportion of specialist oilseed rape weed species tended to increase with herbicide treatment intensity and to decrease with increases in the proportion of spring‐sown crops in the rotation. Changes to the rotation may therefore constitute an additional or alternative means of controlling some weeds well adapted to oilseed rape crops.  相似文献   

16.
Over‐winter mortality, that is, winterkill, reduces cereal crop competitive ability and yield. While management and environmental variables are known to affect winterkill, the extent to which weeds contribute to increased winterkill is largely unknown. Winter annual weeds may increase winterkill through resource competition and by increasing incidence of and damage from plant pathogens that cause winterkill. We evaluated the impact of summer annual (Avena fatua) and winter annual (Bromus tectorum) weeds on the over‐winter survival rate of winter wheat over three winters, during which plots were covered with snow. Pink snow mould (Microdochium nivale), a winterkill pathogen known to infect B. tectorum and winter wheat, was common in wheat stands. In weed‐free treatments, mortality rates were initially near zero, but increased by nearly 45% in each subsequent winter, presumably due to an increase in snow mould disease in continuously cropped winter wheat. Whereas A. fatua infestation had no impact on crop survival rates, winter wheat survival in B. tectorum‐infested plots was 50% less than the weed‐free control in the second and third years of this study. Among B. tectorum‐infested plots, winter wheat over‐winter survival declined with increasing weed seed produced in the previous summer. Overall, this study demonstrated that winter annual weed infestations can reduce crop stand densities below replanting thresholds by reducing fall‐sown cereal winter survival. The effects of winter annual weeds on winter wheat may be meditated by increased proliferation of snow mould disease.  相似文献   

17.
Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Primarily, spatial information allows a potential reduction in herbicide use, when post‐emergent herbicides are only applied to field sections with high weed infestation levels. This paper presents a system for site‐specific weed control in sugar beet, maize, winter wheat, winter barley, winter rape and spring barley. The system includes on‐line weed detection using digital image analysis, computer‐based decision making and Global Positioning System‐controlled patch spraying. In a 2‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 6–81% for herbicides against broad leaved weeds and 20–79% for grass weed herbicides. Highest savings were achieved in cereals followed by sugar beet, maize and winter rape. The efficacy of weed control varied from 85% to 98%, indicating that site‐specific weed management will not result in higher infestation levels in the following crops.  相似文献   

18.
A Collavo  M Sattin 《Weed Research》2014,54(4):325-334
In Europe, glyphosate‐resistant weeds have so far only been reported in perennial crops. Following farmers' complaints of poor herbicide efficacy, resistance to glyphosate as well as to ACCase and ALS inhibitors was investigated in 11 populations of Lolium spp. collected from annual arable cropping systems in central Italy. Field histories highlighted that farmers had relied heavily on glyphosate, often at low rates, as well as in a non‐registered crop. The research aimed at elucidating the resistance status, including multiple resistance, of Lolium spp. populations through glasshouse screenings and an outdoor dose–response experiment. Target‐site resistance mechanism was also investigated for the substitutions already reported for EPSPs, ALS and ACCase genes. Three different resistant patterns were identified: glyphosate resistant only, multiple resistant to glyphosate and ACCase inhibitors and multiple resistant to glyphosate and ALS inhibitors. Amino acid substitutions were found at position 106 of the EPSPs gene, at position 1781, 2088 and 2096 of the ACCase gene and at position 197 and 574 of the ALS gene. Not all populations displayed amino acid substitutions, suggesting the presence of non‐target‐site‐mediated resistance mechanisms. After 39 years of commercial availability of glyphosate, this is the first report of multiple resistance involving glyphosate selected in annual arable crops in Europe. Management implications and options are discussed.  相似文献   

19.
An acetolactate synthase (ALS)‐resistant Amaranthus retroflexus biotype was collected in a soyabean crop after repeated exposure to imazethapyr and thifensulfuron‐methyl in north‐eastern Italy. Studies were conducted to characterise the resistance status and determine alternative post‐emergence herbicides for controlling this biotype. Whole‐plant bioassay revealed that the GR50 values were 1898‐ and 293‐fold higher than those observed for the biotype susceptible to imazethapyr and imazamox respectively. The biotype also displayed high cross‐resistance to sulfonylureas. Molecular analysis demonstrated that a single nucleotide substitution had occurred in domain B (TGG to TTG at position 574), conferring a change from the amino acid tryptophan to leucine in the resistant biotype. However, herbicides with other modes of action (PSII, 4‐HPPD and PPO inhibitors) provided excellent control. The GR50 ratios for metribuzin, terbuthylazine and mesotrione were close to 1 and treatments with fomesafen gave 100% control of both susceptible and resistant biotypes at the recommended field dose. This study documents the first case of an imidazolinone and ALS‐resistant biotype in European crops and identifies the post‐emergence herbicide options available for managing this troublesome weed in soyabean crops. Alternative management strategies are also discussed.  相似文献   

20.
ALS抑制剂的杂草抗性概述   总被引：4，自引：0，他引：4  
随着化学除草剂的不断推广和使用,杂草抗性问题也日益加重。本文搜集了2003年和2007年各种不同作用机制药剂的杂草抗性的报道,重点搜集、整理并分析了ALS抑制剂的最近杂草抗性研究报道,其相关抗性机理,并探讨了ALS抑制剂抗性杂草治理措施。  相似文献   

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