Combined effects of wheat competition and 2,4-D amine on phenoxy herbicide resistant Raphanus raphanistrum populations

Phenoxy herbicides are integral to the control of Raphanus raphanistrum populations in Australian crop production systems, but the development of phenoxy resistant R. raphanistrum populations poses a major threat to the sustainability of these systems. In dose–response pot studies, phenoxy herbicide resistant R. raphanistrum populations, WARR12 and WARR20, suffered large biomass reductions following treatment with recommended or higher application rates of phenoxy herbicides. This indicates the presence of a weak resistance mechanism where treated plants, although surviving, are affected by these herbicides. Subsequently, the competitive ability of 2,4-D amine treated or untreated WARR12 and WARR20 populations with wheat was assessed using a target-neighbourhood experiment. The combination of wheat competition and 2,4-D amine application resulted in control of the resistant WARR12 population, but not the WARR20 population. Wheat crop competition alone resulted in large (>40%) biomass reductions of WARR12 and WARR20 populations. However, the application of the recommended rate of 2,4-D amine caused a large (>75%) reduction in WARR12 biomass, but had a reduced effect on WARR20 biomass. These studies possibly explain the largely successful control of R. raphanistrum populations being achieved with phenoxy herbicides in cropping systems across the Western Australia wheatbelt. However, the results also indicated that the strategy of combining crop competition with phenoxy herbicides for the control of this weed is likely to be an effective option in the short-term only.     

Multiple herbicide‐resistant Lolium rigidum (annual ryegrass) now dominates across the Western Australian grain belt

Lolium rigidum (annual or rigid ryegrass) is a widespread annual weed in cropping systems of southern Australia, and herbicide resistance in L. rigidum is a common problem in this region. In 2010, a random survey was conducted across the grain belt of Western Australia to determine the frequency of herbicide‐resistant L. rigidum populations and to compare this with the results of previous surveys in 1998 and 2003. During the survey, 466 cropping fields were visited, with a total of 362 L. rigidum populations collected. Screening of these populations with the herbicides commonly used for control of L. rigidum revealed that resistance to the ACCase‐ and ALS‐inhibiting herbicides was common, with 96% of populations having plants resistant to the ACCase herbicide diclofop‐methyl and 98% having plants resistant to the ALS herbicide sulfometuron. Resistance to another ACCase herbicide, clethodim, is increasing, with 65% of populations now containing resistant plants. Resistance to other herbicide modes of action was significantly lower, with 27% of populations containing plants with resistance to the pre‐emergent herbicide trifluralin, and glyphosate, atrazine and paraquat providing good control of most of the populations screened in this survey. Ninety five per cent of L. rigidum populations contained plants with resistance to at least two herbicide modes of action. These results demonstrate that resistance levels have increased dramatically for the ACCase‐ and ALS‐inhibiting herbicides since the last survey in 2003 (>95% vs. 70–90%); therefore, the use of a wide range of integrated weed management options are required to sustain these cropping systems in the future.     

Sensitivity of Echinochloa crus‐galli populations to maize herbicides: a comparison between cropping systems

Echinochloa crus‐galli is an important maize weed with significant variation in herbicide sensitivity. This differential response may reflect differences in selection pressure caused by years of cropping system‐related herbicide usage. The herbicide sensitivity of E. crus‐galli populations from three divergent cropping systems was evaluated in dose–response pot experiments. Populations were collected from sandy fields with (i) a long‐term organic cropping system, (ii) a conventional cropping system with maize in the crop rotation or (iii) a conventional cropping system with long‐term monocropping of maize. Each cropping system was represented by six E. crus‐galli populations. The effectiveness of three foliar‐applied maize herbicides (nicosulfuron, cycloxydim and topramezone) and two soil‐applied maize herbicides (S‐metolachlor and dimethenamid‐P) was tested at three doses and two runs. Foliar‐applied herbicides were applied at the three true leaves stage. Soil‐applied herbicides were applied immediately after sowing. The foliage dry weight per pot was determined 4 weeks after treatment. Plant responses were expressed as biomass reduction. Herbicide sensitivity was consistently lowest for populations from maize monocropping systems. Compared with populations from organic cropping systems, populations from monocropping systems showed 6.9%, 9.8% and 29.3% lower sensitivity to cycloxydim, topramezone and nicosulfuron respectively. Populations from the conventional crop rotation system showed intermediate sensitivity levels, which did not significantly differ from sensitivity levels of populations from the other cropping systems. Sensitivity to dimethenamid‐P and S‐metolachlor was not affected by cropping system. Environmental conditions influenced herbicidal response . This study indicated that integrated weed management may be necessary to preserve herbicide efficacy over the long term.     

Seed production of Raphanus raphanistrum following herbicide application during reproduction and effects on wheat yield

The influence of weather and agronomic factors on the activity of six selective herbicides applied at reproductive stages of development for the reduction in seed production of Raphanus raphanistrum in wheat was evaluated. The herbicides used in this way generally reduced seed production by between 80% and 100%. Triasulfuron and mixtures of triasulfuron + MCPA consistently provided the greatest reduction in seed production. This was greater when herbicides were applied at the bud and early flowering stages of R. raphanistrum and the efficacy of the herbicides increased as maximum temperature on the day of spraying increased over the range 14–24°C. An applied model developed from these results predicts the reduction in seed production of R. raphanistrum, for each herbicide, given the stage of weed development and maximum temperature on the day of its application. Wheat yield was significantly reduced as densities of R. raphanistrum increased, with predicted losses at low densities being approximately half of those reported in the literature. There was no consistent evidence that the late application of herbicides had any negative effect on wheat yield through crop injury, nor was there any indication of yield improvement. It is concluded that certain herbicides applied during the reproductive phase of development have considerable potential to reduce R. raphanistrum seed production in wheat crops. As part of an integrated strategy, such late post‐emergence application of selective herbicides to regulate seed production has a likely role for managing weed seedbanks, but little or no value for counteracting weed competition.     

Non-target-site-based resistance to ALS-inhibiting herbicides in six Bromus rigidus populations from Western Australian cropping fields

BACKGROUND: Bromus rigidus is a common weed species that has increased in cropping fields owing to limited control options. During a random field survey in Western Australia, six B. rigidus populations that had survived in‐crop weed control programmes were collected. The study aimed to determine the resistance profile of these six populations. RESULTS: Based on dose–response studies, all six B. rigidus populations had a low‐level resistance to sulfosulfuron and sulfometuron (both sulfonylurea herbicides) while remaining susceptible to herbicides with other modes of action. ALS in vitro activity assays revealed no differences in enzyme sensitivity between susceptible and resistant populations, while the use of malathion (a cytochrome P450 inhibitor) in combination with sulfosulfuron caused the resistant populations to behave like the susceptible population. CONCLUSION: This study established that these six B. rigidus populations have a low‐level resistance to the ALS‐inhibiting sulfonylurea herbicides, but are able to be controlled by other herbicide modes of action. The low‐level, malathion‐reversible resistance, together with a sensitive ALS, strongly suggest that a non‐target‐site enhanced metabolism is the mechanism of resistance. Copyright © 2012 Society of Chemical Industry     

Chemical control of herbicide-resistant Lolium rigidum Gaud. in north-eastern Spain

BACKGROUND: Lolium rigidum Gaud. is one of the most common weed species in winter cereals in north‐eastern Spain, with populations that have evolved resistance to herbicides becoming more widespread since the mid‐1990s. Nine trials on commercial fields with herbicide‐resistant L. rigidum were conducted during the cropping seasons 2001–2002 to 2003–2004, testing the efficacy of 20 herbicides and mixtures pre‐ and post‐emergence and as sequential applications. Weed populations chosen had different resistance patterns to chlortoluron, chlorsulfuron, diclofop‐methyl and tralkoxydim, representative of the resistance problems faced by farmers. RESULTS: In pre‐emergence, prosulfocarb mixed with trifluralin, chlortoluron or triasulfuron was effective on six populations. In post‐emergence, iodosulfuron alone or mixed with mesosulfuron gave the best results but did not control three resistant populations. At Ferran 1, none of the herbicide combinations reached 90% efficacy. CONCLUSIONS: The diverse efficacy patterns of the different populations demonstrate the need for detailed knowledge of the populations before using herbicides. Moreover, the unexpected insufficient efficacy of the new herbicide iodosulfuron prior to its field use shows the need to combine herbicides with other non‐chemical weed control methods to control resistant L. rigidum in north‐eastern Spain. Copyright © 2010 Society of Chemical Industry     

Multiple herbicide resistance in littleseed canarygrass (Phalaris minor): A threat to wheat production in India

Littleseed canarygrass (Phalaris minor Retz.), a troublesome weed of wheat in India, has evolved multiple herbicide resistance across three modes of action: photosynthesis at the photosystem II site A, acetyl‐coA carboxylase (ACCase), and acetolactate synthase inhibition. The multiple herbicide‐resistant (MHR) populations had a low level of sulfosulfuron resistance but a high level of resistance to clodinafop and fenoxaprop (ACCase inhibitors). Some of the populations had GR₅₀ (50% growth reduction) values for clodinafop that were 11.7‐fold greater than that of the most susceptible population. The clodinafop‐resistant populations also showed a higher level of cross‐resistance to fenoxaprop (fop group) but a low level of cross‐resistance to pinoxaden (den group). Although clodinafop and pinoxaden are from two different chemical families (fop and den groups), their same site of action is responsible for cross‐resistance behavior. The populations that were resistant to four groups of herbicides (phenylureas, sulfonylurea, aryloxyphenoxypropionate, and phenylpyrazolin) were susceptible to the triazine (metribuzin and terbutryn) and dinitroaniline (pendimethalin) herbicides. The P. minor populations that were resistant to the aryloxyphenoxypropionate and phenylurea herbicides were effectively controlled by the sulfonylurea herbicide, sulfosulfuron. In the fields infested with P. minor that was resistant to clodinafop, a sulfosulfuron application (25 g ha^?1) increased the wheat yield by 99.2% over that achieved using the recommended rate of clodinafop (60 g ha^?1). However, the evolution of multiple resistance against the four groups is a threat to wheat production. To prevent the spread of MHR P. minor populations, as well as the extension of multiple resistance to new chemicals, concerted efforts in developing and implementing a sound, integrated weed management program are needed. The integrated approach, consisting of crop and herbicide rotation with cultural and mechanical weed control tactics, should be considered as a long‐term resistance management strategy that will help to sustain wheat productivity and farmers' income.     

Identification of resistance to either paraquat or ALS-inhibiting herbicides in two Western Australian Hordeum leporinum biotypes

BACKGROUND: Hordeum populations are becoming increasingly difficult to control in cropping fields. Two herbicide‐resistant H. leporinum populations were identified during a random crop survey after herbicides were applied. The study aimed to determine the herbicide resistance profile of these H. leporinum biotypes to a range of herbicides used for their control. RESULTS: Based on dose–response studies, one H. leporinum population was very highly resistant to sulfosulfuron and sulfometuron (both sulfonylurea herbicides) and also displayed low‐level resistance to imazamox (an imidazolinone herbicide). Reduced sensitivity of the ALS enzyme was identified with in vitro activity assays. Gene sequence analysis revealed a proline‐to‐threonine substitution at amino acid position 197 of ALS, which is likely to be the molecular basis for resistance in this population. Herbicide screening also revealed a different H. leporinum population with resistance to the bipyridyl herbicide paraquat. CONCLUSION: This study established the first cases of (1) sulfonylurea‐to‐imidazolinone cross‐resistance and (2) field‐evolved paraquat resistance in a Hordeum species in Western Australia. Copyright © 2012 Society of Chemical Industry     

Paraquat-resistant biotypes of Hordeum glaucum from zero-tillage wheat

There has been a significant increase in the area seeded to minimum- and zero-tilled crops worldwide over the past two decades. These cropping systems rely primarily on the non-selective herbicides glyphosate or paraquat/diquat to control weeds before seeding the crop. Both glyphosate and paraquat/diquat are regarded as low-risk herbicides in the ability of target weeds to develop resistance to them. Following 10–15 years of once annual applications of paraquat and diquat for weed control in zero-tilled cereals, failure of these herbicides to control Hordeum glaucum Steud. in two separate fields occurred. Dose–response experiments demonstrated high-level resistance to paraquat and diquat in both populations; however, the resistant biotypes are susceptible to other herbicides. This is the first report, worldwide, of paraquat resistance following the use of this herbicide in zero-tillage cropping systems and is therefore a harbinger of future problems in minimum-tillage systems when there is exclusive reliance on a contact herbicide for weed control.     

You cannot fight fire with fire: a demographic model suggests alternative approaches to manage multiple herbicide‐resistant Avena fatua

Multiple herbicide‐resistant (MHR ) weed populations pose significant agronomic and economic threats and demand the development and implementation of ecologically based tactics for sustainable management. We investigated the influence of nitrogen fertiliser rate (56, 112, 168, or 224 kg N ha^?1) and spring wheat seeding density (67.3 kg ha^?1 or 101 kg ha^?1) on the demography of one herbicide susceptible and two MHR Avena fatua populations under two cropping systems (continuous cropping and crop‐fallow rotation). To represent a wide range of environmental conditions, data were obtained in field conditions over 3 years (2013–2015). A stochastic density‐dependent population dynamics model was constructed using the demographic data to project A. fatua populations. Elasticity analysis was used to identify demographic processes with negative impacts on population growth. In both cropping systems, MHR seedbank densities were negatively impacted by increasing nitrogen fertilisation rate and wheat density. Overall, MHR seedbank densities were larger in the wheat‐ fallow compared with the continuous wheat cropping system and seedbank densities stabilised near zero in the high nitrogen and high spring wheat seeding rate treatment. In both cropping systems, density‐dependent seed production was the most influential parameter impacting population growth rate. This study demonstrated that while the short‐term impact of weed management tactics can be investigated by field experiments, evaluation of long‐term consequences requires the use of population dynamics models. Demographic models, such as the one constructed here, will aid in selecting ecologically based weed management tactics, such as appropriate resource availability and modification to crop competitive ability to reduce the impact of MHR .     

Prevalence of herbicide‐resistant weed species in Malaysian rice fields: A review

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.     

An approach to investigate the costs of herbicide‐resistant Alopecurus myosuroides

Herbicide resistance in Alopecurus myosuroides causes severe problems in Western European cropping systems. Costs of herbicide resistance were investigated in this study by analysing variable production costs and sales revenues. Three farms were selected for this study, with winter wheat as the dominating crop in all farms. Resistance in A. myosuroides populations was verified at all locations. Four farming approaches were simulated over a period of 20 years: (i) continuing the actual cropping system without increase of resistance, (ii) continuing the actual cropping system with increase of resistance, (iii) changing cropping practice to overcome resistance and (iv) changing cropping practice to prevent resistance. Contribution margins representing the proportion of sales revenue that is not consumed by variable costs were calculated for all approaches. Comparative static simulations showed that average contribution margins in a cropping system with more than 60% winter cereals and reduced tillage practice dropped from 807 € ha^?1 a^?1 without herbicide resistance to 307 € ha^?1 a^?1 with herbicide resistance. Alopecurus myosuroides population densities increased to more than 1000 plants m^?2. Diverse crop rotations, including spring crops, clover–grass leys and intensive tillage, suppressed A. myosuroides populations, and average contribution margin was 630 € ha^?1 a^?1. Preventive methods with rotations of winter cereals and spring crops with less clover–grass leys resulted in an average contribution margin of 691 € ha^?1 a^?1. In conclusion, rotations of winter cereals and spring crops combined with inversion tillage and herbicides provide stable yields and can prevent weed population increase.     

Real-time weed detection, decision making and patch spraying in maize, sugarbeet, winter wheat and winter barley

Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Most of all, it allows a potential reduction in herbicide use, when post‐emergence herbicides are only applied to field sections with weed infestation levels higher than the economic weed threshold; a review of such work is provided. This paper presents a system for site‐specific weed control in sugarbeet (Beta vulgaris L.), maize (Zea mays L.), winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.), including online weed detection using digital image analysis, computer‐based decision making and global positioning systems (GPS)‐controlled patch spraying. In a 4‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 60% for herbicides against broad‐leaved weeds and 90% for grass weed herbicides. In sugarbeet and maize, average savings for grass weed herbicides were 78% in maize and 36% in sugarbeet. For herbicides against broad‐leaved weeds, 11% were saved in maize and 41% in sugarbeet.     

Are herbicides a once in a century method of weed control?

The efficacy of any pesticide is an exhaustible resource that can be depleted over time. For decades, the dominant paradigm – that weed mobility is low relative to insect pests and pathogens, that there is an ample stream of new weed control technologies in the commercial pipeline, and that technology suppliers have sufficient economic incentives and market power to delay resistance – supported a laissez faire approach to herbicide resistance management. Earlier market data bolstered the belief that private incentives and voluntary actions were sufficient to manage resistance. Yet, there has been a steady growth in resistant weeds, while no new commercial herbicide modes of action (MOAs) have been discovered in 30 years. Industry has introduced new herbicide tolerant crops to increase the applicability of older MOAs. Yet, many weed species are already resistant to these compounds. Recent trends suggest a paradigm shift whereby herbicide resistance may impose greater costs to farmers, the environment, and taxpayers than earlier believed. In developed countries, herbicides have been the dominant method of weed control for half a century. Over the next half‐century, will widespread resistance to multiple MOAs render herbicides obsolete for many major cropping systems? We suggest it would be prudent to consider the implications of such a low‐probability, but high‐cost development. © 2017 Society of Chemical Industry     

Improved chemical control of Conyza bonariensis in wheat limits problems in the following fallow

Conyza bonariensis is a major weed infesting zero‐tilled cropping systems in subtropical Australia, particularly in wheat and winter fallows. Uncontrolled C. bonariensis survives to become a problem weed in the following crops or fallows. As no herbicide has been registered for C. bonariensis in wheat, the effectiveness of 11 herbicides, currently registered for other broad‐leaved weeds in wheat, was evaluated in two pot and two field experiments. As previous research showed that the age of C. bonariensis, and to a lesser extent, the soil moisture at spraying affected herbicide efficacy, these factors also were investigated. The efficacy of the majority of herbicide treatments was reduced when large rosettes (5–15 cm diameter) were treated, compared with small rosettes (<5 cm diameter). However, for the majority of herbicide treatments, the soil moisture did not affect the herbicide efficacy in the pot experiments. In the field, a delay in herbicide treatment of 2 weeks reduced the herbicide efficacy consistently across herbicide treatments, which was related to weed age but not to soil moisture differences. Across all the experiments, four herbicides controlled C. bonariensis in wheat consistently (83–100%): 2,4‐D; aminopyralid + fluroxypyr; picloram + MCPA + metsulfuron; and picloram + high rates of 2,4‐D. Thus, this problem weed can be effectively and consistently controlled in wheat, particularly when small rosettes are treated, and therefore C. bonariensis will have a less adverse impact on the following fallow or crop.     

Tillage and herbicide treatments with inter‐row cultivation influence weed densities and yield of three industrial crops

Field experiments were conducted in northern Greece in 2003 and 2004 to evaluate effects of tillage regimes (moldboard plowing, chisel plowing, and rotary tilling), cropping sequences (continuous cotton, cotton‐sugar beet rotation, and continuous tobacco) and herbicide treatments with inter‐row hand hoeing on weed population densities. Total weed densities were not affected by tillage treatment except that of barnyardgrass (Echinochloa crus‐galli), which increased only in moldboard plowing treated plots during 2003. Redroot pigweed (Amaranthus retroflexus) and black nightshade (Solanum nigrum) densities were reduced in continuous cotton, while purple nutsedge (Cyperus rotundus), E. crus‐galli, S. nigrum, and johnsongrass (Sorghum halepense) densities were reduced in tobacco. A. retroflexus and S. nigrum were effectively controlled by all herbicide treatments with inter‐row hand hoeing, whereas E. crus‐galli was effectively reduced by herbicides applied to cotton and tobacco. S. halepense density reduction was a result of herbicide applied to tobacco with inter‐row hand hoeing. Yield of all crops was higher under moldboard plowing and herbicide treatments. Pre‐sowing and pre‐emergence herbicide treatments in cotton and pre‐transplant in tobacco integrated with inter‐row cultivation resulted in efficient control of annual weed species and good crop yields. These observations are of practical relevance to crop selection by farmers in order to maintain weed populations at economically acceptable densities through the integration of various planting dates, sustainable herbicide use and inter‐row cultivation; tools of great importance in integrated weed management systems.     

Impact of crop management on weed species diversity and community composition of winter wheat fields in Iran

The aim of this study was to assess the effects of crop management practices on the diversity, structure, and composition of weed communities. A total of 30 fields (15 fields each) in low‐input and conventional farming systems were surveyed in north‐eastern Iran. In the conventional cropping system, both mineral fertilizers and herbicides were applied, while in the low‐input cropping system, the fertilizer was mainly manure and herbicides were avoided. The results showed that the pool of species, species richness, number of unique species, and Shannon's diversity index were greater in the low‐input system than in the conventional system. Both cropping systems had more broad‐leaved species than grasses and more annual species than perennial species. All the multivariate methods of analysis that were applied revealed that the weed community composition was significantly different between the two management types. The low‐input cropping favored herbicide‐susceptible broad‐leaved weeds, legumes, and weeds with biodiversity value, whereas a high proportion of herbicide‐tolerant grasses was found in the conventional fields. The results suggest that low‐input cropping can sustain high weed diversity and abundance.     

Invasiveness of agronomic weed species in wheat in Western Australia

Weed seeds are introduced to agronomic systems naturally or through human-mediated seed dispersal, and introduced seeds have a high chance of being resistant to selective, in-crop herbicides. However, colonisation (invasion) rates for a weed species are usually much lower than rates of seed dispersal. The current research investigated colonisation of a winter annual wheat cropping system in Western Australia by a range of winter or summer annual weed species. The weed seeds were sown (at 100 seeds/m²) directly before seeding the crop in 2016 and allowed to grow in the following 3 years of wheat. Selective herbicides were not applied, to simulate growth of weed populations if the initial seed had been resistant to herbicide. Bromus diandrus, Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus, Polygonum aviculare, Lolium rigidum, Citrullus amarus and Tribulus terrestris colonised the crop, while Dactyloctenium radulans, Chloris truncata and Salsola australis failed to establish over 3 years. The most successful weed was B. diandrus, with a plant density of 1,170/m² by the third year and seed production of 67,740/m². The high density of B. diandrus reduced wheat density by 76% in the third year and reduced average yield by 36%. Lolium rigidum reduced average yield by 11%, and the other weed species did not affect crop yield. Further research is required on the invasiveness of these species in other regions, but it is clear that the spread of B. diandrus to new areas or the introduction of resistant B. diandrus seeds via contaminated grain should be avoided.     

Integrated management of Bromus diandrus in dryland cereal fields under no‐till

As herbicides have limited effect in controlling Bromus diandrus in no‐till dryland cereal fields, the integration of chemical and cultural methods needs to be investigated. A field study was carried out in Lleida (Spain) during 2008–09, 2009–10 and 2010–11 seasons, in a no‐till winter cereal field integrating delayed crop sowing with herbicides in a barley–wheat–wheat rotation. Three crop sowing dates were considered: D1, mid‐October; D2, mid‐November; and D3, early December, and the herbicides mesosulfuron‐methyl plus iodosulfuron‐methyl‐sodium were applied in wheat. Weed density, cumulative emergence and fecundity were estimated for each sowing date. In all three seasons, a significant reduction in the cumulative emergence of B. diandrus as compared to D1 was observed in D2 (82.0, 97.5 and 98.1%) and D3 (80.8, 98.7 and 97.2%). In addition, a significant decrease in weed density and seed rain was observed across all sowing dates and seasons. The herbicide used in wheat was more effective under delayed sowing, due to lower weed density and presence of less developed weed seedlings. After three seasons, the populations of B. diandrus were completely depleted in D2 and D3. This study demonstrates the possibility of eliminating brome infestations in dryland cereal fields in no‐till systems through the integration of cultural and chemical strategies.