In experiments conducied from 1988 io iSSO at four locations in the Parkland zone of western Canada, the drydown of seed and foliage, seed yield, seed quality and baking quality of wheat (Titicum aestivarn L.) following preharvest applications of glyphosaie were compared with moie following windrowing prior to harvest or direct cutting of the standing crop. Glyphosate wai applied in late July to early September at rates of 0.45,0.9 and 1.7 kg acid equivalent ha-'to wheat with seed moisture contents ranging from 80 to ll%. When compared with a standing crop, all glyphosate treaunents applied at seed moisturg c9n-tents above 25% slightly enhanced the drydown of wheat seed and foliage. Treatments applied at seed moisture contents below 25% had no effect on either seed or foliage drydown. Seed yields were generally greater from plots to which glyphosate was applied than from windrowed control plots, although in one of five experiments the reverse trend occurred. Increasing the rate from 0.45 to 1.7 kg ha-r had no effect on yield. Windrowing or applying glyphosate to wheat with a seed moisture content of 6l% or more reduced yields more than windrowing or applying glyphosate at seed moisture contents below this level. In experiments where the wheat in both control and sprayed plots wasdirect cut at maturity, average yields decreased as the rate of glyphosate increased from 0 to 1.7 kg ha-l. However, applications at seed moisture of 40% or less, caused little or no yield loss. ihere was little or no difference in 1000-seed weight, sample density, seed germination and protein content from plots sprayed with glyphosate at seed moisture contents below 40% than from control plots windrowed at the same moisture content oi direct cut at maturity. Baking quality was not affected by any of the glyphosate treafinents in experiments where the wheat was harvested by direct cutting.Key words: Glyphosate, wheat, desiccation, wheat quality, Triticum aestivum Darwent, A. L., Kirkland (Sheppard et al. 1982). In Canada, investigations by Clarke (1981) (Fig. 1) Lacombe (88) Lacombe (89) Beaverlodge (88) Beaverlodge (89) Beaverlodge (90) Melfort ( All statistical analyses were performed using release 2.1 of GENSTAT (Iawes Agricultural Trust 1990). RESULTS Seed and Foliage DrydownSeed moisture content was influenced by the factors location, rate of glyphosate, time of sampling and seed moisture class and by the interactions location, rate ofglyphosate and seed moisture class with time of sampling ( Table 2). None of the three-way interactions was significant.The drydown of wheat seed was enhanced by the application of glyphosate. Mean seed moisture content, averaged across locations and seed moisture classes, was similar in all plots at 5 d after application, but was 3.6, 5.0 and 17 .2Vo lower in glyphosate-sprayed plots than in control plots at 1988, 1989 and 1990. seeds and converting to g per 1000 seeds. After weighing, these seeds were subjected to standard germination tests Baking quality. The effect of the glyphosate trea...

In a 2-yr study at four locations in western Canada, residues of glyphosate and its major metabolite aminomethyl-phosphonic acid (AMPA) were measured in the seed and foliage of wheat (Triticum aestivum L.) following preharvest applications at rates of 0.45, 0.9 or 1.7 kg acid equivalent ha−1. Herbicide treatments were applied in early August to mid-September at seed moisture contents ranging from 52 to 12%. Glyphosate and AMPA residues in the seed increased as the rate of application increased, and decreased as the seed moisture content at the time of application decreased. However, when the maximum application rate of 1.7 kg ha−1 was sprayed at seed moisture contents of 40% or less, glyphosate residues in the seed were < 5 mg kg−1, the Maximum Residue Level recently established by Health Canada. Glyphosate and AMPA residues in the straw also increased with increasing application rate, but there was no consistent pattern in residues of either chemical with seed moisture content at the time of application. Physiological maturity of the crop, rainfall washoff, and application rate appeared to play important roles in determining the magnitude of glyphosate and AMPA residues in the seed and straw of wheat. Key words: Glyphosate, AMPA, residues, wheat, seed, preharvest application

No abstract

. 2002. Residues of glyphosate and its metabolite AMPA in field pea, barley and flax seed following preharvest applications. Can. J. Plant Sci. 82: 485-489. Maximum residue levels have been established by Health Canada for seed of several crops treated with preharvest applications of glyphosate, a common practice on the Canadian prairies. Residues of glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) were determined at crop maturity in flax seed at one site in western Canada and in the seed and straw of field pea and barley at another site following preharvest applications of the herbicide. Glyphosate was applied at rates of 0.45, 0.9 and 1.7 kg ha -1 to each crop in early August to mid-September at four stages of crop development. In all crops, mean residues of glyphosate and AMPA increased with increasing application rate of glyphosate and decreased when the herbicide was applied at later stages of crop development.

. 2000. Residues of glyphosate and its metabolite AMPA in canola seed following preharvest applications. Can. J. Plant Sci. 80: [425][426][427][428][429][430][431]. Residue data for glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) in canola seed following preharvest application of glyphosate were lacking when this 2-yr study was initiated. Residues of glyphosate and AMPA were measured in the seed of canola (Brassica rapa L.) at maturity following preharvest application at rates of 0.45, 0.9 or 1.7 kg acid equivalent ha -1 at four sites in western Canada. Herbicide treatments were applied in early August to mid-September at four stages of crop development, which encompassed seed/pod moisture contents ranging from 74 to 12%. Rate of glyphosate application and the physiological maturity of the crop at application played important roles in determining the magnitude of glyphosate and AMPA residues in the seed of preharvest-treated canola. In general, for a given site, mean residues of glyphosate and AMPA in the seed increased with increasing application rate, and decreased with application at later stages of crop development. In 1989, mean residues of glyphosate in the seed for all application rates at the latest stage of development at each site were <1 mg kg -1 . In 1988, when seed/pod moisture content generally declined very slowly from stage 1 to stage 3 and then decreased rapidly, corresponding mean residues were higher and varied from <1 to 19.7 mg kg -1 . Seed/pod moisture was not a reliable indicator of stage of canola development and, consequently, the magnitude of glyphosate and AMPA residues in the seed.Key words: Glyphosate residues, AMPA residues, canola, preharvest treatment Cessna, A. J., Darwent, A. L., Townley-Smith, L., Harker, K. N. et Kirkland, K. J. 2000. Importance des résidus du glyphosate et de son métabolite AMPA dans les graines de navette canola résultant des traitements de prérécolte. Can. J. Plant Sci. 80: 425-431. Nous avons mesuré pendant 2 ans la présence des résidus du glyphosate et de son principal métabolite, l'acide aminométhylphosphonique (AMPA), dans les graines de navette canola (Brassica rapa L.) à la suite de traitements herbicides de prérécolte. Trois doses de traitement au glyphosate, 0,45, 0,9 et 1,7 kg équivalent acide par hectare, étaient comparées à 4 emplacements de l'ouest canadien. Les traitements, échelonnés du début d'août à la mi-septembre, étaient exécutés à 4 stades phénologiques de la culture durant lesquels la teneur en eau des gousses ou des graines qu'elles renferment descendait de 74 à 12 %. L'importance des résidus de glyphosate et de AMPA dépendait fortement de la dose de l'herbicide et du degré de maturité physiologique de la culture lors du traitement. Dans l'ensemble, à un emplacement donné, les quantités moyennes de résidus augmentaient avec la dose, mais elles diminuaient plus le stade de maturité lors du traitement était avancé. En 1989, les quantités moyennes de résidus de glyphosate résultant du traitement, toutes doses confond...