Weed Profile: Chess, Bromus secalinus L.
Table of Contents
Bromus secalinus is not an extremely common weed in Ontario and is mainly found in cereal crops. However seeds of Bromus secalinus are restricted in several American States and prohibited in India, Taiwan and possibly other countries. Therefore any amount of Bromus secalinus found in grain samples could have trade implications.
Competitiveness: Field Studies in Oklahoma have shown 28-48% yield loss when winter wheat was competing with a 25 plants/m2 average density of Bromus secalinus1.
Bromus secalinus is recognized as a noxious weed seed under the U.S. Federal Seed Act. This designation does allow up to 300 Bromus secalinus seeds per pound of certified seed in the following American States2: Alabama, Arkansas, Delaware, Florida, Georgia, Kansas, Louisiana, Mississippi, New Jersey, Oklahoma, South Carolina, Tennessee, and Texas.
The following countries prohibit the importation of Bromus secalinus:
Annual or winter annual, reproducing only by seed.
Stems: 30 - 90 cm (1 - 3 ft) tall, single or 3 to 4 stems from 1 root crown (Figure 1, "A"). Stems are smooth but finely hairy on the nodes. Node hairiness is only visible with magnification (Figure 2, "a").
Roots: Fibrous (Figure 1, "A").
Leaves: 3 - 9 mm (1/8 - 3/8 in.) wide, either smooth or softly hairy (Figure 2, "b") on either or both surfaces. The leaf sheaths smooth or lower ones hairy; leaf sheaths of lower leaves closed (margins united) nearly to the top (Figure 2, "c"); upper leaf sheaths split with margins (Figure 2, "d") overlapping or separate.
Inflorescence: a panicle with rather stiff, nearly erect branches (Figure 3);
Spikelets: Have a firm, plump appearance 1 - 2 cm long, 6 - 10 mm wide (Figure 1, "B: and Figure 2, "f"), hairless with short awns (Figure 1, "B" and Figure 2, "g") that are usually 1-5 mm long but are sometimes absent, each spikelet having 5 to 15 seeds (Figure 1, "B" and Figure 2, "h"). Mature grain is deeply grooved and the grain cross section appears "U-shaped" (Figure 4).
Flowering Period: June to August.
Distinguishing Characteristics: It is distinguished by its annual or winter annual habit, its firm, plump spikelets, its smooth stems with finely hairy nodes, and the combination of lower leaf sheaths closed and upper ones split with overlapping margins.
There are currently no quantitative data on the amount and distribution of Bromus secalinus in Ontario. Bayer CropScience, a herbicide manufacturer conducted a phone survey of 93 agricultural retail supply businesses in 2005 to identify problematic weed species throughout Ontario. Participants were also asked to rank each identified species in terms of their importance for management with "10" being most important and "1" being least important. One of the ninety-three survey participants identified "wild bromegrass" as a problematic species and ranked it a "3" in terms of importance for management. It is unclear as to whether or not "wild bromegrass is Bromus secalinus, Bromus racemosus, Bromus inermis or any of the other "brome grass" weeds.
Dore and McNeil (1980), stated that prior to the 21st century, "Bromus secalinus was considered a serious weed in the wheat growing areas of the southwestern counties but is no longer regarded as a serious weed"5. This sentence apparently reflected the status of the weed as of the late 1970's.
There are 128 specimens of Bromus secalinus catalogued at the University of Guelph, Agriculture and Agri-Food Canada Herbariums. Figure 5 illustrates the location of specimen samples throughout Ontario. This map is not an indication of severity of the species, only were it has been detected historically. This species is not exclusive to agricultural fields, as it has been found along roadsides, railways and ports. The majority of specimens however have come from cereal fields with herbarium notes indicating that in general this is a weed species that is "rare" and "scattered".
Although a few herbicide options exist in Western Canada and the United States, none are currently registered in Ontario. The following herbicides have proven to be effective on Bromus secalinus in Oklahoma1:
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