of 120 d under ice cover without damage (Beard 1965). Total submersion in ice causes greater damage than Damage as a result of ice cover on putting greens affects golf partial submersion or ice cover only (Andrews and Pomcourses in cold climates. The objectives of this study were to assess cold-hardiness levels and injury of annual bluegrass [Poa annua f. eroy, 1975;Beard, 1964a). reptans (Hausskn.) T. Koyama] and creeping bentgrass (Agrostis Freyman and Brink (1967) in their study on ice cover stolonifera L. cv. Penncross) under ice cover maintained for various in alfalfa concluded that CO 2 accumulation was the periods of time under laboratory and field conditions. In the lab, prime factor in the death of herbaceous plants under cold-hardened plants of both species were subjected to either snowice sheets. In turfgrasses, Beard (1964a) suggested that covered, ice-covered, or ice-encased treatments and tested for coldcombinations of freezing and thawing in association with hardiness levels at various periods of time. Ice-encased annual bluegrass high plant tissue moisture levels might be of greater plants stored for 90 d were dead, while ice-covered and snow-covered significance than direct oxygen suffocation or toxic accuplants had cold-hardiness levels of Ϫ4؇C and Ϫ18؇C, respectively. In mulations. Rochette et al. (2000) attributed the cause contrast, at 150 days after treatment (DAT), creeping bentgrass that of ice injury on putting greens to the development of was ice encased had a cold-hardiness level of Ϫ18؇C, while snowcovered plants had a cold-hardiness level of Ϫ27؇C. In the field, bluegrass (biotype MN 42 provided by the University of Min-2004. *Corresponding author (jross@oldscollege.ca).nesota) and Penncross creeping bentgrass plants were allowed

A snow management system, which utilizes no‐till seeding into standing stubble immediately after harvest of the previous crop, has permitted the expansion of winter wheat (Triticum aestivum L.) production in western Canada. The effect of seed rate and row spacing on grain yield and yield components of no‐till winter wheat were evaluated in 21 trials conducted in Saskatchewan from 1986 to 1988. Two winter wheat cultivars were evaluated in eight of the trials. The relationship between grain yield (Y) and seed rate was best described by a modified inverse polynomial: Y = uSR(1‐SR/566)/(SR + u/104) where u represents the upper limit of yield when seed rate is not limiting. This curve accounted for 98% of the observed variation in grain yield. Optimum seed rate varied from 58 kg ha−1 at a very dry trial to 148 kg ha−1 in a trial with more favorable growing conditions. Grain yield increased as row spacing decreased and the effect of row spacing on pain yield was increased under more favorable growing conditions. Increased seed rate and decreased row spacing interacted positively to increase grain yield so optimum seed rate increased as row spacing decreased. Increased spikes per square meter was responsible for the increase in grain yield associated with high seed rate and narrow row spacing. In contrast, kernel weights were slightly higher with low seed rate and kernels per spike were higher with low seed rate and wide row spacing. Optimum seed rate was higher for the cultivar ‘Norstar’ than for ‘Norwin’ due to higher yield potential of Norstar under the conditions experienced in this study.

Changes in cold hardiness levels of annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis palustris Huds.) were monitored under field conditions during the dehardening period of late winter and early spring. During the course of two spring periods the cold hardiness levels of the two species were monitored in conjunction with the following hydration treatments: snow cover maintained to prolong dormancy, snow removal in March, and hydration of crown tissues in combination with snow removal. Cold hardiness levels, percent crown moisture, and soil temperatures were monitored throughout this period. Cold hardiness levels were significantly influenced by year, species, hydration treatment, and a number of interactions of these factors. Generally, plants dehardened 2 wk earlier in 1997 than in 1996. On 1 April, creeping bentgrass had cold hardiness levels averaging −20°C compared to −13°C for annual bluegrass. By 15 April, creeping bentgrass plants had lost their cold hardiness advantage. Increased soil temperature was the greatest contributor to the loss of hardiness in the spring. An increase in crown moisture of 4% for annual bluegrass and 6% for creeping bentgrass occurred during the period from 25 March to 22 April. Maintaining a snow cover on plots delayed the loss of cold hardiness by 6 to 9 d in 1996 but had no effect in 1997. Maintaining a snow cover also delayed the increase in crown hydration by a week. Plants were able to partially regain cold hardiness when soil temperatures dropped.

Management practices are required in rainfed agriculture of western Canada to reduce early season water evaporation from soil relative to loss by transpiraition. The objective of this study was to measure the effect of two seed rates and two row spacings on the pattern of water use and writer use efficiency (WUE) of no‐till winter wheat (Triticum aestivum L.). Nine field trials were conducted on Udic Haploboroll and Molllic Cryoboralf soils in Saskatchewan from 1987 to 1989. Higher dry matter production and more rapid early season plant ground cover associated with the 9 cm row spacing and 140 kg ha−1 seeding rate, compared to other row spacing‐seeding rate combinations reduced water loss from evaporation and increased the partitioning of evapotranspiration to transpiration during the pre‐anthesis growth period. Pre‐anthesis water use was 11% higher, post‐anthesis wateir use 6% lower, and growing season water use 4% higher for the 140 compared to the 35 kg ha−1 seeding rate, The 140 kg ha−1 seeding rate produced 40% more preanthesis dry matter than the 35 kg ha−1 rate, thus establishing a higher yield potential for the crop. A row spacing of 9 compared to the 36 cm resulted in water use that was 6% higher during the pre‐anthesis, growth period and 3% higher during the entire growing season. The combination of 140 kg ha−1 seeding rate and 9 cm row spacing ultimately produced a 21% higher grain yield and a 9 kg cm‐−1 higher WUE than the combination of 35 kg ha−1 seeding rate and 36 cm row spacing. Grain protein concentration increased from 13.1% with the 35 kg ha−1 seeding rate to 13.9% with the 140 kg ha−1 seeding rate. Grain protein yield increased from 198 to 227 kg ha−1 for the 35 compared to the 140 kg ha−1 seeding rate. The increase in grain protein concentration and yield associated with 140 kg ha−1 seeding rate was related to the pattern of water use by the crop. Even under conditions of high dronght stress, a larger number of more uniformly distributed plants associated with seeding rates higher than 35 kg ha−1 and row spacings narrower than 36 cm resulted in a higher WUE and a water use pattern that produced larger yields and higher grain protein concentration.

Feedlot manure, containing seeds of twelve weed species, was composted in a windrow to determine whether composting would kill the weed seeds. The twelve species of weeds included: Thfnpsi arvensc, Polygonum comolzwliis, Aiienn fntua, Chenopodium album, Setarin viridis, Galeopsrs tetrahit, Poly,yoiruiri pcrsicorio, Ainnrnnflius retrojlexus, Kochin scopnrin, Gnlium npnrine, Malm rotundrfolm, and Mntrrcnrrn pevfornta. The windrow was managed to maintain core temperatures between 55°C and 65°C for as long as possible.After two weeks of composting, seeds of Gnlriirii npnrriie, Sctnrm zvrrdis, Kocliin scoparin, Mntricarin pevforatn, Thlapsi amense and Poly~yoniiin cotivolvulirs had 0 percent viability in a tetrazolium test. Seedsof Amnrnnflius retrt$cwis had a viability of 3 5 percent, the highest of the twelve species studied. After four weeks of composting, the viability for all twelve species was 0 percent. Therefore, seed viability was extremely low after even two weeks of windrow composting and four weeks of composting was enough to kill all seeds of the twelve species studied. IntrodtictionThe disposal of cattle manure is a problem for many feedlot operators. Feedlot manure is typically land spread, but this may lead to increased weed problems. For example, Blackshaw and Rode (1991) found that many weed species (including Sctaria viridis, Kochia scoparia, Antaranthus refroflexus, Ckenopodiirnr albtini, Pol!jgonu ttt convolvulus, and Mdva rotzrndifolin) were able to survive rumen digestion. The proportion of the population that was able to survive varied with species.There is a common perception that composting kills weed seeds. However, there has been little documentation of this. A study done in Florida by Shiralipour and McConnell, 1991, reported that certain weed species were killed when placed in a pile of composting yard waste. This only held true when the seeds were exposed to high temperatures within the pile.Egley, 1990, reported that killing temperatures vary inversely with the moisture content of the seed. Consequently, moist seeds within a compost pile should be killed at a lower temperature than dry seeds of the same species. Materials and MethodsTwelve commonly occurring weeds in western Canada, were chosen for this experiment. These species include weeds from a number of different families (Table 1) nd have a range of seed coat hardness. Preliminary StudyA preliminary study was carried out at the Olds College Composting Centre. be maintained within the optimum range to kill the seeds of the twelve selected species of weeds. Windrows of a typical feedlot manure mixed with beddingThe goal was to determine how long the compost windrow temperatures must