Seed production and retention at maturity of blackgrass (Alopecurus myosuroides) and silky windgrass (Apera spica-venti) at wheat harvest

Abstract

Blackgrass (Alopecurus myosuroides Huds.) and silky windgrass [Apera spica-venti (L.) P. Beauv.] are becoming a significant problem in Europe. Due to the development of herbicide-resistant biotypes and unwanted side effects of herbicides, there is a need for new integrated weed management strategies to control weeds. Therefore, reducing weed infestations by targeting seed production during crop harvest should be considered. In 2017 and 2018, we estimated the fraction of the total seed production of A. myosuroides and A. spica-venti in a field that potentially could be collected by a grain harvester during winter wheat (Triticum aestivum L.) harvest. Twenty plants of each species were surrounded by a porous net before flowering to trap shed seeds during reproductive development. Seeds were collected and counted weekly up until and immediately before wheat harvest, and the ratio of harvestable seeds to shed seeds during the growing season was determined. Alopecurus myosuroides produced on average 953 seeds plant−1 in 2017 and 3,337 seeds plant−1 in 2018. In 2017 and 2018, 29% and 37% of the total A. myosuroides seeds produced, respectively, were retained on plants at maturity. Apera spica-venti produced on average 1,192 seeds plant−1 in 2017 and 5,678 seeds plant−1 in 2018, and retained 53% and 16% of the seeds at harvest, respectively. If a grain harvester potentially collected approximately 30% of the total seed production of the two grass weeds and removed or killed them, it would reduce seed input to the soil seedbank. However, such methods cannot stand alone to reduce weed pressure.

Growth and Phenology of Vulpia Myuros in Comparison with Apera Spica-Venti, Alopecurus Myosuroides and Lolium Multiflorum in Monoculture and in Winter Wheat

“…The pattern of seed shedding between V. myuros and L. multiflorum was inconsistent across the years probably because of different growing conditions between the 2 years ( Figure 1). Similar to our results, Bitarafan and Andreasen [41] reported earlier seed shedding in A. myosuroides than A. spica-venti over two growing seasons, and variation in the timing of seed shedding due to different climatic conditions was observed between the years. The percentages of seeds retained on the plants of A. spica-venti and A. myosuroides were 35% and 34%, respectively, at winter wheat harvest in Denmark [41].…”

Biology and Management of Vulpia myuros—An Emerging Weed Problem in No-Till Cropping Systems in Europe

“…The successful implementation of weed seed harvest in Australia can be attributed to the fact that a large fraction of L. rigidum seeds is retained at crop maturity [84]. Visual observations indicate that V. myuros sheds the majority of its seeds several weeks before winter wheat maturity, as was recently observed for A. spica-venti and A. myosuroides [85]. Thus, the weed seed harvest method may not be as effective as for L. rigidum, but it may contribute to the long-term control of V. myuros and serve as a last resort in fields where other control measures have failed.…”

Killing Weed Seeds with Exhaust Gas from a Combine Harvester

“…Thereby, the seeds are not incorporated into the soil seed bank, creating new weed problems in the coming season. However, many weed species shatter a smaller or larger proportion of their seeds before harvest [38,39]; therefore, the effect strongly depends on the weed composition in the field. Walsh and Powels [40] found that some of the most important weed species in Australia-L. rigidum, Raphanus raphanistrum L., Bromus spp., and Avena fatua L.-retained 85%, 99%, 77%, and 84% of their seeds above a 15 cm harvest cutting height at wheat (Triticum aestivum L.) maturity.…”