Summary: Differential growth and response to atrazine were examined in greenhouse experiment with three populations of Chenopodium album from southwestern Ontario: two known susceptible (SI. SII) and one resistant (R). Germination of the resistant biotype was less than SII but the same as SI. R seedlings were not as mature at 16 days and weighed less at 23 days than seedlings of SI and SII. Within SI. early‐(ESI) and late‐flowering (LSI) variants were recognized. Older plants of R (37 and 44 days) had a greater growth rate than two of the susceptible populations (LSI and SII). In terms of vegetalive, floral, and total biomass. mature individuals of ESI were less productive than the other populations, but devoted a greater percentage of dry weight to floral production. Young plants (37 days old) were sprayed with atrazine at 00125, 0.25, 0.5, 1.25, 2.5 and 5 kg/ha. Population ESI was most sensitive to at razine; height and weight of stems and production of new leaves showed decreases at 0.25 and 0.125 kg/ha. respectively, compared to the untreated. Populations LSI and SII showed greater tolerance and decreases in these characters occurred at a higher rate of atrazine. Leaf weight per plant decreased at 0.25 kg/ha as a result of decreases in weight per unit area of leaf for all susceptible population. Growth of R as measured by the above criteria was not affected by atrazine treatments but leaf weight per unit area was slightly reduced at 2.5 and 5.0 kg/ha Single leaves of 48 day old plants were infused with at razine concentrations of 0.5, 2.0, 3.0 and 20.0 ppm. Leaf chlorosis increased with concentration and injury was greater in populations LSI and SII than in ESI. A small amount of chlorosis occurred in R.

WARWICK, S. I., and P. B. MARRIAGE. 1982. Geographical variation in populations of Chenopodium album resistant and susceptible to atrazine. I. Between-and within-population variation in growth and response to atrazine. Can. J. Bot. 60: 483-493. Between-and within-population variation in growth characteristics, isoenzyme patterns, and response to atrazine were studied in individuals from four atrazine-resistant (R) and four susceptible (S) populations of Chenopodium album L. collected from sites of contrasting climate in southern Ontario. In both the R and S types, population differences in growth characteristics were correlated with geographical location and climatic differences. The more northerly R and S populations had a greater rate of development, earlier maturation, lower biomass at maturity, and greater reproductive effort compared, respectively, with the more southerly R and S populations.Estimates of within-population variation were obtained statistically for a number of growth characters and from the electrophoretic patterns of five enzyme systems (PGM, PGI, GOT, MPI, and LAP). These indicated marked homogeneity in the four R populations as compared with the more variable S populations. Populations from the two disjunct areas of resistance were different for two of the enzymes studied and would appear to represent two different genotypes. This would suggest that mutation for resistance in populations of C. album has occurred independently in the two areas. Coupled with the evidence for differential growth characteristics of these two genotypes in response to climate, we would suggest that resistance has developed in individuals already established in each of the two separate areas, rather than spreading from a single recent introduction of the R type in Ontario.As expected, distinct differences between the R and S types were obtained in response to postemergence treatments with atrazine. The four R populations either showed no effect or exhibited increased growth. S populations all showed marked decreases in growth and production of biomass. Significant between-population differences in growth features were apparent for both types in the control and were maintained in the presence of atrazine. Although small differences in relative susceptibility were obtained for the susceptible populations, statistically significant population by treatment interactions were not evident. WARWICK, S. I., et P. B. MARRIAGE. 1982. Geographical variation in populations of Chenopodiurn album resistant and susceptible to atrazine. I. Between-and within-population variation in growth and response to atrazine. Can. J. Bot. 60: 483-493. La variation entre populations et a l'interieur des populations de Chenopodiurn album L. dans leurs caractkristiques de croissance, leurs patrons isoenzymatiques et leurs reactions 2i l'atrazine a Cte Ctudiee chez des individus de quatre populations resistantes (R) et de quatre populations susceptibles (S) i l'atrazine provenant de sites climatiquement differents du sud de llOntario. Chez les ty...

R6siim£: ZusammenfassungAnnual applications of the herbicides atrazine, simazine, linuron and diuron at 4 5 kg/ha were made to the same plots for 9 consecutive years from 1963 to 1971 in a peach {Prunus persica (L.) Batsch.) orchard located on sandy loam soil near Harrow, Ontario. Soil samples from these plots were collected in late October for the last 3 years (1969)(1970)(1971) and trees were cut down in December, 1969. Herbicide residues were determined by bioassays based on the fresh and dry weight of oats {Avena sativa L.) and in one year results were confirmed by chemical analysis. Significant accumulation of herbicides was not observed. The maximum residue levels measured in October over the 3 years of sampling were 7'3 kg/ha for diuron, 3-8 kg/ha for linuron, 1 -6 kg/ha for simazine and 0 4 kg/ha for atrazine in the top 15 cm ofthe soil profile. Simazine and atrazine showed a rapid decrease in amount after treatment but diuron and linuron were degraded more slowly. Measurable residues of all herbicides were confined to the upper 15 cm of the soil profile and the majority of herbicide remained in the 0-5-cm soil layer. Oats were planted in the orchard plots from 1972 to 1974 to follow the disappearance ofthe herbicides. All herbicides caused highly significant yield decreases in 1972, atrazine causing the least (38%) and diuron the greatest (86%) reductions. Diuron reduced the yield of oats in 1973 and caused a highly significant decrease in the weight of young oat plants in 1974. Rhidus d'atrazine, de simazine, de linuron et de diuron apris des applications annuelles ripetees dans un verger de pechers.Des applications annuelles avec les herbicides suivants: atrazine (2-chloro-4-6thyIamino-6-isopropylamino-l,3,5-triazine), simazine (2-chloro-4,6-bis6 thylamino-1,3,5-triazine), linuron (Ar'-(3,4-dichloroph6nyl)-Af-m6thoxy 7V-m6thylur6e) et diuron (Af'-3,4-dichloroph^nyl)-A'Af-dim^thyIur6e) i 4,5 kg/ha, ont tit faites sur les memes parcelles pendant neuf annees cons6cutives, de 1963 a 1971, dans un verger de pechers {Prunus persica (L.) Batsch.), implant6 dans un sol de • Present address: Research Branch, Agriculture Canada, Ottawa, Ontario, Kl A 0C6.

No abstract

A sensitive, selective, and simple procedure is described for the analysis of the herbicide glyphosate. The method involves aqueous extraction of glyphosate from the sample, in situ preparation of the N-nitroso derivative with sodium nitrite at pH 3.0, thin-layer chromatographic separation on silica gel, degradation of iV-nitrosoglyphosate to aminomethylphosphonic acid with ultraviolet light, and fluorophore formation from this primary amine with fluorescamine. As little as 10 ng (45 pmol) of glyphosate could be detected, and with a minimum of sample cleanup 5 ppm was easily determined in 2-mg samples of the one plant investigated. Roots taken 1, 3, or 6 days after treatment of Canada thistle leaves with 40 mg of glyphosate per plant showed residue levels of 30-60 ppm. Recoveries in spiked samples ranged from 75% at 5 ppm to 90% at 100 ppm, and the precision of the determinations was about ±9%.