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Development of integrated weed management strategies is dependent on a thorough knowledge of the demography of individual species. The current research established eight winter or summer weed species in a winter annual wheat cropping system at Wongan Hills, Western Australia, and investigated emergence of the first cohort of each species, survivorship, plant size, seed production and seed shedding over three years (2016–2019). The winter weeds Bromus diandrus and Lolium rigidum emerged at the same time as the wheat crop, and the initial cohort of marked plants had 100% survival to seed production in each year. By comparison, other winter weed species like Hordeum leporinum, Rumex hypogaeus, Sonchus oleraceus and Polygonum aviculare frequently emerged later than the crop and had a lower percentage of plants surviving to seed production. However, individual S. oleraceus and P. aviculare plants had the greatest seed production compared to other species. All winter weeds had variable patterns of seed shedding between years, with the exception of L. rigidum. Summer weed species emerged at the same time, but plants in the initial cohort of each species did not always survive to produce seed. The early emergence and high survivorship of B. diandrus indicates high competitive ability, but shedding commenced at a similar time to L. rigidum and harvest weed seed control may be a viable control method for this species. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Phalaris minor Retz. is the major grass weed of wheat, which has developed resistance to multiple herbicides working through three modes of action. The identification of suitable herbicides with different modes of action will assist in the control of this weed in resistance affected areas. Keeping this in view, the efficacy of flufenacet, an oxyacetanilide herbicide, was investigated in 2013 and 2014 at Ludhiana, India. Three doses of flufenacet (200, 250 and 300 g ha−1) were tested at three application timings on Zadoks wheat stages (Z00, Z13 and Z21) and compared with clodinafop application and weedy check for the control of resistant P. minor biotype. Flufenacet 250 and 300 g ha−1, applied at Z00 and Z13 wheat stages, had more than 85% mortality and more than 90% growth reduction of P. minor compared to the unsprayed check (76–109 plants m−2; 60–69 g m−2) at 45 days after sowing in both years, whereas clodinafop just provided 26–37% reduction in density and 39–40% reduction in biomass of this weed. Flufenacet 250 g ha−1 at Z00 and Z13 produced better wheat grain yield (4.2–4.5 t ha−1) in both years, while weed competition in the unsprayed check reduced wheat grain yield by 54–67% (1.75–1.97 t ha-1). This study suggests that flufenacet could be used to control multiple herbicide resistant P. minor in northern Indian wheat production systems. • Flufenacet 250 – 300 g ha−1 applied at Z00 and Z13, provided >85% mortality and >90% growth reduction of P. minor. • Clodinafop @ 60 g ha−1 provided only 26–37% reduction in density and 39–40% reduction in biomass of P. minor. • Flufenacet efficacy was higher in 2014 over 2013, owing to higher rainfall events in second year. • Flufenacet 250 g ha−1 applied at Z00 and Z13 produced better wheat grain yield (4.2–4.5 t ha−1) in both years. • Flufenacet provided better control of resistant P. minor population as compared to clodinafop. [ABSTRACT FROM AUTHOR]

Four field experiments were conducted over a three-year period in Victoria and South Australia to investigate the effectiveness of pre-emergence (PRE) applications of pyroxasulfone, flufenacet and their mixtures with triallate for the control of Bromus diandrus in spring wheat. Herbicide mixtures of pyroxasulfone plus triallate and flufenacet plus triallate applied PRE to wheat provided consistently high levels of B. diandrus control (≥85%). In contrast, applications of pyroxasulfone and flufenacet applied alone along with trifluralin plus metribuzin (a common farmer practice in southern Australia) provided more variable control of B. diandrus (33–90%). Pyroxasulfone plus triallate treatments had a much lower (≤47 panicles m −2 ) panicle density of B. diandrus than trifluralin plus metribuzin (42–318 panicles m −2 ) and the non-treated control (118–655 panicles m −2 ). PRE herbicides which were safe to spring wheat and provided the greatest level of control of B. diandrus resulted in significantly ( P < 0.05) higher grain yields at Culgoa (120%) and Gama (13%) than non-treated wheat (720 and 1740 kg ha −1 ). Although flufenacet was effective against B. diandrus , crop phytotoxicity at the higher dose (900 g ai ha −1 ) reduced spring wheat grain yield. Based on these results, PRE pyroxasulfone plus triallate could play an important role in the management of B. diandrus in spring wheat. However, high cost of these herbicides (AUS$35-$70 ha −1 ) may limit their adoption in low rainfall and low yielding wheat environments in southern Australia where B. diandrus is most prevalent. [ABSTRACT FROM AUTHOR]

Abstract: Five field experiments were undertaken over a three-year period in South Australia to investigate the efficacy of imidazolinone herbicides for the control of rigid brome in imidazolinone-tolerant wheat (Clearfield™, CLF). Imidazolinone herbicides, imazapyr, imazapyr plus imazapic and imazapyr plus imazamox applied post-emergence to imi-wheat (cvs. CLF-Janz and CLF-Stiletto) at the four-leaf stage, provided consistent and high levels of rigid brome control (≥87%). In contrast, applications of the alternative herbicide mesosulfuron-methyl (post-emergence) provided limited and variable control of rigid brome (11–67%). Furthermore, imidazolinone treatments caused a large reduction (P <0.05) in rigid brome seed production (≤6 seedsm−2) as compared to mesosulfuron-methyl (461–3983 seedsm−2) and the non-treated control (2257–11 865 seedsm−2). Imazapyr plus imazapic provided consistent control of rigid brome and resulted in higher grain yields (28–45%) than wheat treated with mesosulfuron-methyl. Based on these results post-emergence applications of imazapyr, imazapyr plus imazapic and imazapyr plus imazamox to imi-wheat could play an important role in the management of rigid brome in southern Australia. However, the effect of these herbicides on existing and new cultivars of imi-wheat (multiple-gene resistance) and issues concerning persistence in low rainfall environments and crop damage on sandy soils require attention. [Copyright &y& Elsevier]

Highlights: [•] Heat stress accelerated leaf senescence and genotypes with faster senescence suffered higher yield loss in wheat. [•] Wheat grain yield was strongly correlated with post-heading duration and heat stress reduced post-heading duration. [•] Heat stress reduced grain number and individual grain mass but grain number was more sensitive to heat stress. [•] There was a strong consistency in the impact of heat stress on grain yield of wheat under all growing conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heat stress reduced peduncle WSC content and its mobilization in wheat. [•] IGM in wheat genotypes with lower peduncle WSC was more sensitive to heat stress. [•] Mobilization of peduncle WSC was strongly correlated with the maximum peduncle WSC. [•] There was a positive correlation between mobilized WSC and relative IGM. [Copyright &y& Elsevier]