The efficacy, residue, and future for triazine herbicides in Canola

Non-Peer Reviewe

Maximum economic yield as related to weed populations and herbicide use

Non-Peer ReviewedEconomic threshold levels and relative time of emergence for numerous common grassy and broad-leaved weed species in small grains will be discussed. The importance of understanding; weed species present, control options available and proper application timing are presented as essential elements in achieving maximum economic yield. Recent research results on the role of adjuvants, ammonium sulfate, water volumes and droplet sizes in improving control and reducing costs will be reviewed

Cruiciferae weed control in canola through the use of triazine resistant varieties

Non-Peer Reviewe

A comparison of herbicides to control wild oats in wheat

Non-Peer Reviewe

Effect of management practices on stubble yields of wheat

Non-Peer Reviewe

Implication of reduced herbicide rates on resistance enrichment in wild oat (Avena fatua)

Non-Peer ReviewedModel simulations predict that lowering herbicide efficacy by reducing the application rate would slow the rate of enrichment of herbicide-resistant individuals in a weed population, but the resulting increase in density of susceptible plants would reduce crop yield and increase the weed seedbank. A study was conducted at three sites in Saskatchewan from 1997 to 2000 to examine the implication of reduced rates of Group 1 herbicides in a 4-year crop rotation, in conjunction with variable crop seeding rates, on the enrichment of resistant wild oat in a mixed (resistant and susceptible) population. Main plot treatments were crop (barley, canola, field pea, spring wheat), subplot treatments were crop seeding rate (recommended and high), and sub-subplot treatments were Group 1 herbicide rate (0, 0.33, 0.67, and 1.0 times the recommended rate). Herbicide rate frequently interacted with seeding rate in affecting wild oat seedling density, seed return, the viable fraction of the weed seedbank, and crop seed yield. As simulation models predict, reduced herbicide efficacy decreased the proportion of resistant individuals in the population. The high crop seeding rate compensated for a one-third reduction in herbicide rate by limiting total wild oat seed return and by reducing the number of resistant seedlings recruited from the seedbank. In a diverse cropping system, the level of resistance in the seedbank can be reduced without increasing the total (resistant plus susceptible) seedbank population by manipulating agronomic practices to increase crop competitiveness against wild oat when Group 1 herbicide rates are reduced to a maximum of two-thirds of that recommended

Conserving crop residue for erosion protection on summerfallow

Non-Peer ReviewedConserving crop residues on the soil surface has proven to be one of the most effective means of controlling wind erosion on summerfallow. Tillage practices are constantly changing and some recent trends have given rise to concern over their effect on wind erosion; namely the widespread use of mounted harrows on cultivators and use of higher tillage speeds. Results of these studies suggest that both practices decrease residue conservation on summerfallow. Use of mounted harrows deceased residue conservation by approximately 50 % compared with cultivators alone. Similarly, increasing tillage speeds from 5 to 10 to 15 km/h decreased residue conservation to approximately 50 and 30 %, respectively, of that conserved at 5 km/h. Depth of tillage had little effect on residue conservation after 2 operations but deeper tillage significantly reduced residues in subsequent operations. Where herbicides were substituted for tillage operations, both total and anchored residues increased as the number of tillage operations replaced was decreased. These results indicate that elimination of mounted harrows would have a very substantial impact on wind erosion. Where weed control needs to be enhanced, occasional use of trailed rod weeder attachments would be preferred. Reducing tillage speeds and minimizing depths of operation would also be beneficial. Where initial residue levels are, low, substituting herbicides for some or all tillage operations will likely be required to provide adequate protection

The effect of management practices in a continuous wheat rotation on weed populations

Non-Peer ReviewedA five-year field study was conducted at five locations in west central and north west Saskatchewan to determine the effect of cropping practices on weed populations in a continuous wheat rotation. Fall tillage, normal stubble height, tall stubble, and varying fertility levels (N and P) did not directly influence populations of grassy and broad-leaved weeds. In general, there was no significant differences between the herbicide combinations on grassy and broad-leaved weed populations at any of the five sites. Diclofop methyl (Hoegrass) applied as a tank mix with bromoxynil (Torch) or as a separate application with chlorsulfuron (Glean) or Bromoxynil/MCPA (Buctril M) and Triallate (Avadex BW) applied in the fall, followed by 2,4-D amine in the spring all reduced weed populations significantly. Yield increases from the application of Hoegrass plus Glean, Hoegrass/Torch, Hoegrass plus Buctril M and Avadex + 2,4-D were 21, 22, 19, and 15 % respectively

Seeding depth and triallate for semi-hard and hard red spring wheats

Non-Peer ReviewedThe depth of seeding study was conducted with Hy-320, Hy-355 , Line-912 and Neepawa wheats sown at depths of 2.5, 5.0, 7. 5, and 10.0 cm. Depth of seeding significantly affected all variables measured except bushel weight. There were no variety × depth interactions indicating that all varieties reacted the same to seeding depth. In general deeper seeding delayed emergence and maturity and reduced the number of plants. Maximum plant stand in the presence of triallate occurred at the 5.0 cm. depth with triallate-applied pre-emergent incorporated. When applied pre-plant incorporated, the presence of triallate reduced plant stands as seeding depth increased. There was no differential varietal responses to triallate

Yield of continuous spring wheat with several combinations of stubble, weed control, and fertility management

Non-Peer ReviewedStudies to evaluate stubble management, weed control, and fertility treatments applied in combination in a continuous spring wheat (Triticum aestivum L.) rotation were conducted over a seven year period (1983-89) at Scott, Lashburn and Loon Lake and over a four year period (1983-86) at Kindersley and Mervin. Leaving stubble standing overwinter at either a normal swathing height or with strips of taller stubble as snow-traps gave yields equal to or significantly greater than fall tillage. Use of herbicides for control of broad-leaved and grassy weeds generally increased yield as did application of nitrogen and phosphate fertilizers. Yields were increased from 910 to 1970 at Scott; 1300 to 2450 at Lashburn; 940 to 1600 at Loon Lake; 1150 to 2420 at Kindersley; and from 1920 to 2920 at Mervin where herbicides and fertilizers were applied in combination with tall stubble compared with no herbicide or fertilizer application. The occurrence and nature of interactions between factors suggest a need to conduct more studies to evaluate interactions of cropping system components. In developing sustainable crop production systems it is likely that improved efficiencies will arise from development and manipulation of entire cropping systems rather than individual components