Species studied at Lincoln, Nebraska for 4 years were downy brome (Bromus tectorum L.), hairy chess (B. commutatus Schrad.), Japanese chess (B. japonicus Thunb.), and cheat (B. secalinus L.). These grasses were usually winter annuals, but also became spring annuals or biennials when sown in late March or early April.
In the greenhouse, an inductive period either of vernalization or short day lengths appeared necessary for panicle production by downy brome and hairy chess. For both species, long day lengths following the inductive period were necessary for flowering.
When a mixture of smooth bromegrass (Bromus inermis Leyss.) and 5.4 per cent of weed bromegrasses was sown in the fall, weed bromes made up 48 per cent of the total basal density and 87 per cent of the total seed yield the following summer. Panicles of weed bromes were absent or nearly so when this mixture was sown soon after April 1.
The best time for mowing hairy chess and downy brome for their control in pasture was approximately one week after the heads had emerged.
Practical control of weed bromegrasses has generally been obtained by prevention of seed production for two years. A practical program has included killing all emerged weed bromegrasses by tillage between April 1 and heading. A spring cereal or row crop, such as corn or sorghum, was then planted. The next season, timely tillage followed by the above crops, or summer fallow, has permitted return of fields to the usual alternate winter wheat and fallow sequence.
Effective control of weed bromegrasses also was accomplished by isopropyl N-phenylcarbamate (IPC), isopropyl N-(3-chlorophenyl) carbamate (CIPC), 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), sodium salt of trichloracetic acid (TCA), 3,6–endoxohexahydrophthalic acid (endothal), 4,6-dinitro-o-sec-amylphenol (DNAP), and mixtures of these herbicides.