The voluntary digestible organic matter intake (DOMI) of mature barley crops (Hordeum spp.) for sheep depends largely on straw quality. Direct measurement of DOMI is laborious; consequently, the research reported here evaluated indicator traits for improving barley straw DOMI by crop breeding. It hypothesized that some indicator traits for straw quality are heritable, facilitate genetic gain in DOMI, and reveal straw properties that constrain genetic gain. In 4 years, 32 genotypes of barley were grown at ICARDA, northern Syria, with no fertilizer in one year and supplementary irrigation in another. Indicator traits for predicting DOMI included in situ straw dry matter losses (DML) at nine incubation times (0–120 h), four parameters of the DML curve, seven laboratory tests, grain yield and straw yield. Heritability (h2) was highest for traits associated with indigestible cell wall constituents, including potential DML (h2 = 0.61), DML at 48–120 h of incubation (h2 = 0.48–0.58), and acid detergent fibre (ADF) (h2 = 0.41). Heritability was lower for DOMI itself (h2 = 0.24), neutral detergent fibre (NDF) (h2 = 0.20), and total Kjeldahl nitrogen (h2 = 0.17), and was lowest for DML at 6–18 h (h2 = 0.08–0.09) and the in situ parameters Lag and relative loss rate of slowly degradable DM (h2 ≤ 0.03). Correlations between indicator traits and DOMI tended to increase with heritability. Grain and straw yields were not correlated with DOMI; of these, only grain yield was heritable. In conclusion, genetic gain in barley straw nutritive value can be achieved by crop breeding under diverse growing conditions, using indicator traits associated with indigestible cell wall constituents.

The effects of different barley grain preservation techniques on intake, growth and carcase traits of dairy bulls were determined in a feeding trial using 52 Holstein and 48 Nordic Red bulls which were allotted to four feeding treatments (five pens and 25 bulls per treatment). Spring barley was harvested with a conventional combine harvester and four different preservation techniques formed the four experimental treatments. Dry grain (DG) was dried to the targeted dry matter (DM) concentration of 870–880 g/kg and rolled within 7 days prior to feeding. High moisture grain treated with a formic acid-based additive (FA) was harvested and crimped on the targeted DM content of 700 g/kg. Low moisture grain treated with a urea-based additive (UR) and low moisture grain treated with a propionic acid-based additive (PA) were harvested and crimped on the targeted DM content of 800 g/kg. The bulls were fed with total mixed ration ad libitum. On DM basis, the diets included grass silage (500 g/kg), barley grain (485 g/kg) and a mineral–vitamin mixture (15 g/kg). Daily DM intake (DMI) and live weight gain were 6% higher when crimped grains were used instead of DG (P < 0.05). There were no observed significant differences in DMI, gain or carcase traits between high moisture and low moisture crimped grain treatments or between UR and PA. The current results show that producers have the option to vary grain preservation system without major changes to growth performance or carcase traits.

Greenhouse and field experiments were conducted at the Lacombe Research Station to evaluate mixtures of sethoxydim and fluazifop on green foxtail, wild oat, wheat, and barley in canola. In both environments the two herbicides interacted on the grass species in a synergistic manner. Many of the observed responses to mixtures of sethoxydim and fluazifop were 100% greater than those expected assuming an additive interaction between the herbicides. Mixtures with at least 80 g ha-1 of sethoxydim and 80 g ha-1 of fluazifop controlled more than 90% of green foxtail, wild oat, wheat, and barley under field conditions. These experiments indicate that the sethoxydim/fluazifop mixture is both complementary and synergistic. The mixture may allow reduced herbicide application rates and therefore reduced herbicide costs and less potential for negative environmental impact.

The effects of photoperiod and temperature on the translocation of triclopyr {[1(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid}, picloram (4-amino-3,5,6-trichloropicolinic acid) and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] were studied on tanoak [Lithocarpus densiflorus (Hook. & Arn.) Rehd.], snowbush ceanothus (Ceanothus velutinus Dougl.), bigleaf maple (Acer macrophyllum Pursh), bean (Phaseolus vulgaris L. var. ‘Red Kidney’) and barley (Hordeum vulgare L. var. CM-67). Isolation of 14C and analysis for the radioactive herbicides revealed little metabolism of the herbicides. Regardless of herbicide or plant species herbicide movement was greatest under warm temperature and long day conditions. Among the herbicides tested, 14C associated with triclopyr was the most mobile in each species. Each herbicide moved readily in the symplast but root applications of each herbicide revealed limited apoplastic mobility.

Studies were conducted to determine the usefulness of HOE-39866 (HOE-00661) in chemical fallow systems on the Canadian prairies. HOE-39866 at 0.5 to 1.0 kg ai/ha controlled Russian thistle, kochia, green foxtail, wild oats, and wheat comparable to paraquat, glyphosate, and glyphosate plus the isopropylamine salt of 2,4-D. However, control of barley with HOE-39866 was unacceptable. HOE-39866 was compatible in tank mixtures with ammonium sulfate, paraquat, chlorsulfuron, and metsulfuron. Ammonium sulfate improved weed control when HOE-39866 was applied at 0.25 kg/ha but not at 0.75 kg/ha. Adding paraquat at 0.07 to 0.21 kg ai/ha to HOE-39866 improved control of grass species over HOE-39866 alone. Adding chlorsulfuron and metsulfuron to HOE-39866 provided greater initial control of certain species as well as residual control of many weeds. HOE-39866 alone or in conjunction with other herbicides is an alternative to the herbicides used in chemical fallow systems.

Field studies were conducted to study the interaction of sethoxydim or fluazifop-P with clopyralid and/or ethametsulfuron applied as tank mixtures to canola. Control of the indicator species barley, broadbean, and wild mustard with the tank mixtures was comparable to, or sometimes better than, that attained with each herbicide alone. Canola tolerated all herbicides applied individually and all tank mixtures of these herbicides except fluazifop-P and ethametsulfuron. Tank mixtures of fluazifop-P and ethametsulfuron, with or without clopyralid included in the mixture, suppressed early growth of canola in two of four tests and reduced seed yield in one. Sethoxydim, clopyralid, and ethametsulfuron combined in tank mixtures provide an effective POST alternative for selective control of grass and broadleaf weeds in canola.

A standard weed management system (system I) had a higher return above variable costs than did an intensive weed management system (system II) for two eastern Colorado cropping rotations. For continuous corn (Zea mays L.), the return above variable costs averaged $18.85/ha more under system I than under system II. For a barley (Hordeum vulgare L.)-corn-sugarbeet (Beta vulgaris L.) rotation, the return above variable costs averaged $20.48/ha more under System I than under System II. Based on alternative input (herbicide) and product prices, higher herbicide costs favored the standard weed management system, whereas higher crop prices favored the weed management system with the higher yields adjusted for quality. The probability that returns above variable costs differed between the two weed management systems depended upon the level of product prices and herbicide costs.

Above-ground seedling development was characterized for five annual grass weeds: downy brome, bulbous bluegrass, jointed goatgrass, Italian ryegrass, wild oat; and three cereals: winter wheat, winter barley, and winter triticale in field experiments over two years. The rate of leaf production on the main stem of each species was linearly related to cumulative growing degree days (GDD) since planting. Leaf production rates were faster for bulbous bluegrass, downy brome, Italian ryegrass, wild oat, and barley than for wheat, triticale, and jointed goatgrass. The main stem development stage when individual tillers appeared was similar in all species except under poor seedbed conditions in 1991, in which case lower-node tillers were delayed in the cereals and jointed goatgrass, but not in most of the weed species. Bulbous bluegrass, downy brome, and barley had the same percentage of plants produce the first four primary tillers on the main stem in both years; the other species showed more year-to-year variation. Seedling heights at full emergence were generally greater for large-seeded species. Small-seeded species compared to large-seeded species tended to have greater relative increases in plant height over time. Knowledge of comparative development rates between these weeds and cereals could provide information for development of growth models for each of the species and could also improve understanding of the competitive relationships between grass weeds and cereal grains.

Three wash techniques, each with 1, 10, or 95% (v/v) ethanol:water were used to measure foliar absorption of 14C-glyphosate [N-(phosphonomethyl)glycine], 14C-3,6-dichloropicolinic acid, and 14C-chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} in Tartary buckwheat [Fagopyrum tataricum (L.) Gaertn. ♯3 FAGTA], Canada thistle [Cirsium arvense (L.) Scop. ♯ CIRAR], and barley (Hordeum vulgare L. ‘Galt’). For the herbicides and species tested, the most suitable common procedure for determining absorption consisted of a double or triple rinse with or immersion in 10% ethanol. Wiping the treated leaves with cotton balls moistened with the solvent was much less effective. Efficiency of herbicide removal by a given solvent was not related consistently to solubility of the herbicide in the solvent.

The effect of common lambsquarters (Chenopodium album L. #3 CHEAL) density on spring barley (Hordeum vulgare L. ‘Lidal’) was studied in a 2-yr field experiment near Fairbanks, AK. The data were fit to a rectangular hyperbola model. Common lambsquarters densities explained 74 to 75% of the variability in barley yield. The maximum yield loss attributable to common lambsquarters was 23% in 1982 and 36% in 1983.

Postemergence difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) for wild oat (Avena fatua L.) control in spring wheat (Triticum aestivum L.), durum wheat (Triticum durum Desf.), and barley (Hordeum vulgare L.) was evaluated in the field, greenhouse, and controlled environmental chamber. Wild oat control with difenzoquat was greater at the five- that at the three and one-half or two-leaf stages of growth. Barley tolerance to difenzoquat was excellent; however, spring wheat tolerance was influenced by cultivar. Durum wheat generally was more tolerant of difenzoquat than spring wheat. Tank mix combinations of broadleaf herbicides with difenzoquat had no effect on crop injury or wild oat control. Wild oat control with difenzoquat was greatest with adequate soil moisture, adequate fertility, warm air temperatures and high relative humidity. A simulated rainfall of 0.25 mm within ½ h or 1 mm within 4 h of application reduced wild oat control with difenzoquat.

Field experiments were conducted to determine the efficacy of fluazifop-P-butyl for the control of green foxtail, wild oat, barley, and wheat in flax as influenced by spray nozzle orientation, time of day, and growth stage. Under drought conditions in 1988, control of wild oat, wheat, and barley with fluazifop-P-butyl was enhanced 75%, 53% and 78%, respectively, when nozzles were oriented to spray forward 45°. Under adequate soil moisture conditions enhancement of control was minimal. Green foxtail control improved when fluazifop-P-butyl was applied from 1700 to 2100 h, but time of day had no effect on control of wild oat, barley, or wheat. Fluazifop-P-butyl effectiveness was reduced when applied 4 d after flax emergence due to late emerging grass seedlings. Green foxtail was the most tolerant to fluazifop-P-butyl, whereas wild oat, wheat, and barley were the most susceptible.

Field experiments were conducted at the Lacombe Research Station from 1989 to 1991 to determine the influence of various adjuvants on sethoxydim activity. In all experiments sethoxydim was applied at 100 g ai ha-1 to green foxtail, wheat, wild oat, and barley seeded in a canola crop. Of the four grass species, green foxtail was the most susceptible and barley was the least susceptible to sethoxydim. CC 16255 was the most effective adjuvant followed by either of two sources of ammonium sulphate (liquid or granular) and then Merge. Liquid and granular forms of ammonium sulphate were equally effective in enhancing sethoxydim activity. Several other adjuvants, including Enhance, Savol, and XE 1167, were moderately effective in the enhancement of sethoxydim activity. Adding Canplus 411 to Merge was not usually beneficial, but additions of Canplus 411 to Enhance often increased sethoxydim activity compared with sethoxydim and Enhance alone. Agral 90 and LI-700 were of little or no value as adjuvants with sethoxydim.

The control of wild oat, volunteer wheat, and volunteer barley in a flax crop with sethoxydim was enhanced 20 to 27% by orienting the spray nozzles forward 45°. Control of annual grasses was not influenced by the time of day sethoxydim was applied. However, injury to flax from a tank mixture of sethoxydim and bromoxynil/MCPA (1:1) was greatest when applied between 0500 and 1100 h, and least when applied between 1500 and 2300 h. Flax injury and reduced seed yields also resulted when sethoxydim was applied when air temperatures exceeded 30 C regardless of stage of crop growth.

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on barley (Hordeum vulgare L. ‘Steptoe’), corn (Zea mays L. ‘Pioneer 3709′), and sugarbeet (Beta vulgaris L. ‘Mono Hy D2′) production was assessed where these crops were grown in rotation for 6 consecutive years. Weeds were controlled in each crop with a moderate (system I) or intensive (system II) level of herbicides, plus conventional tillage. Weed seeds from seven annual genera were identified, with redroot pigweed (Amaranthus retroflexus L. ♯3 AMARE) and Chenopodium comprising 56 and 30%, respectively, of the initial 1377 million weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of weed seeds in soil was 96% in system I and 97% in system II. Over the 6-yr period, about 1.3 times more weeds escaped control in system I than in system II; and within a crop, the fewest number of weeds escaped annually in sugarbeets, and the most in barley. Yields of barley grain, corn silage, and recoverable sucrose were similar each year in the two weed management systems.

Field studies were conducted over a 7-yr period at Lacombe, Alberta, to study the relationship between the duration of Tartary buckwheat interference [Fagopyrum tatarium (L.) Gaertn. # FAGTA] and yield of barley (Hordeum vulgare L.), oats (Avena sativa L.), wheat (Triticum aestivum L.), flax (Linum usitatissimum L.), and rapeseed (Brassica campestris L.). The data were pooled over years and analyzed by multiple regression. The equations were as follows: ŷ = 15.46 + 0.39X1 + 0.00x2 −0.11x3 (barley), ŷ = −15.44 + 0.49x1 + 0.02x2 + 0.08x3 (oats), ŷ = −2.04 + 0.39X1 + 0.05x2-0.03x3 (wheat), ŷ = −4.38 + 1.14x1 −0.04x2 + 0.01x3 (flax), and ŷ = −13.85 + 0.40x1 – 0.01x2 + 0.04x3 (rapeseed); where ŷ was the estimated percent yield loss of the crop, x1 was the duration (days) of the Tartary buckwheat in the crop, x2 was the number of Tartary buckwheat plants/m2, and x3 was the number of crop plants/m2. The time that Tartary buckwheat remains in the crop contributed most to the yield loss observed in all crops. Yield loss between 0.4 and 1.1% per day was attributed to this variable alone. For a given x1, x2, and x3 value the order of percent yield loss was flax>oats>wheat> barley>rapeseed.

In continuous wheat or barley or in a canola/barley rotation, wild oat control every year over 4 yr maintained wild oat seedling populations at 3 plants/m2 or less. Failure to control wild oats annually increased wild oat populations (>200 plants/m2 by the fourth year) in continuous wheat dramatically, while in the other two cropping systems, populations increased to only 40 plants/m2 or less by the fourth year. In the continuous wheat and in the canola/barley rotation, wild oat control every year generally provided the best economic returns when prices and costs were averaged over 4 yr; in continuous barley, the average return was better when wild oats was controlled only in the second or third years rather than every year.

Experiments were conducted in controlled environmental chambers to determine the influence of temperature on the phytotoxicity of seven soil-applied herbicides. Diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoic acid} soil incorporated or surface applied, was more toxic to wild oat (Avena fatua L.) shoots at 10 and 17 C than at 24 C. Efficacy of diclofop was enhanced with soil incorporation. Diclofop toxicity to wild oat roots was not influenced by a change in temperature. EPTC (S-ethyl dipropylthiocarbamate) stimulated sugarbeet (Beta vulgaris L. ‘American Crystal Hybrid B’) shoot dry weight production at 10 C and caused dry weight reduction at 24 C. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] toxicity to barley (Hordeum vulgare L. ‘Larker’) and alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] toxicity to oats (Avena sativa L. ‘Chief’) increased with increased temperature from 10 to 17 C. Temperatures within the range of 10 to 24 C did not affect trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) toxicity to barley or BAY-5653 [N-(2-benzothiazolyl)-N-methylurea] or chloamben (3-amino-2,5-dichlorobenzoic acid) toxicity to oats.

The effect of glyphosate [N-(phosphonomethyl) glycine] on barley (Hordeum vulgare L.) and corn (Zea mays L.) shoot δ-aminolevulinic acid (ALA) production was examined by monitoring ALA content in the tissue and measuring incorporation of 14C precursors into ALA and chlorophyll a. Barley shoot ALA content was significantly decreased by 1 mM glyphosate after 9, 11, and 15 h of illumination. ALA production by treated barley shoots was 30 nmoles•g fresh weight-1•h-1 at each interval tested, compared with 75 to 120 nmoles•g fresh weight-1•h-1 for the control. In corn shoots, ALA content was reduced 32, 45, and 58% by 0.1, 1.0, and 10.0 mM glyphosate, respectively, after 12 h illumination. Incorporation studies with 14C-glutamate, 14C-α-ketoglutarate, and 14C-glycine into ALA showed a 77, 92, and 91% inhibition, respectively, in barley shoots treated with 1 mM glyphosate. Incorporation of 14C-ALA into chlorophyll a was not affected by 1 mM glyphosate. Thus, the site of action of glyphosate may involve two enzyme pathways:one controlling the conversion of α-ketoglutarate to ALA, and the other controlling the condensation of glycine with succinyl CoA to form ALA and carbon dioxide. Inhibition of ALA synthesis blocks synthesis of chlorophyll, as well as all other porphyrin ring compounds found in higher plants. Thus, inhibition of ALA synthesis may be an integral component of the herbicidal mode of action of glyphosate.

Greenhouse and field experiments were conducted from 1987 to 1990 at the Lacombe Research Station to determine the influence of ammonium sulfate (AS) on various grass control herbicides. In field studies, AS had slight or no effects on the phytotoxicity of aryloxyphenoxypropanoate (APP) herbicides (fenoxaprop, fluazifop, haloxyfop, and quizalofop). The largest AS-mediated increase in APP herbicide phytotoxicity was 19% (based on fresh weight reduction) for wild oat with haloxyfop at 50 g/ha. AS consistently mediated increases in cyclohexanedione (CHD) herbicide phytotoxicity. With added AS, barley fresh weight was reduced 75% (1988) with BAS 517 at 50 g/ha, and 100% (1990) with clethodim at 25 g/ha. Greenhouse studies confirmed field studies, but differences were less substantial and consistent. It is suggested that APP herbicides are either less susceptible to UV degradation than CHD herbicides, and/or that APP herbicides may penetrate plant cuticles quickly enough to nullify any protection from UV degradation that AS might provide via rapid absorption.