Measured and computed concentration patterns of propyzamide in field soils

The persistence of propyzamide in soil was studied by analysing soil samples taken at intervals two or three times after application in the spring to experimental fields. Single samples were taken from other fields. 8 to 12 months after autumn application. The concentrations were measured by electron-capture gas chromatography. Persistence is expressed in first-order dissipation rate constants and half-life values. Data were measured and collected on the adsorption of propyzamide on soils, the soil characteristics and the weather conditions. Computations of the mobility of propyzamide in soil were carried out for simplified systems. Results of measurements and computations are compared.     

Photosynthetic inhibition in Phaseolus vulgaris II. The influence of light on herbicidal action

The influence of pre-treatment and post-treatment illumination upon the herbicidal effect produced in Phaseolus vulgaris L. cv. Berna by simeton, diuron, diquat and ioxynil was examined. The increased effect noted at lower pre-treatment and higher post-treatment levels of illumination was correlated with increased inhibition of net photosynthesis. This increased effect was ascribed to enhanced photo-oxidation.     

THE EFFECT OF SHOOLY LARVAE (DIPTERA) ON GRASS YIELD

Elimination of shooly larvae increased grass yields daring the September feeding period. Increases were usually less than 10% bat in one case, where growth was abnormally slow, die increase was over 30% and in another, where the larval population was atypically dense, it was almost 60%. The effects of damage were not cumulative daring the feeding period; and at the end of this period insecticidreated plots sometimes gave lower yields than untreated plots. Fertilizer increases had a much greater effect on yield than did control of larvae and, where N was applied at 75 kg/ha (67 lb/ac) in spring, the additional effect of larval control was usually negligible. It is suggested that shoot-fly damage may be more serious in other localities. When turf containing shoot-fly larvae was ploughed, Oscinella spp. re-established themselves more successfully than others in seedling ryegrass bat did not damage the new sward appreciably.     

A Comparison of Wood Properties of Coastal and Interior Provenances of Lodgepole Pine Pinus contorta Dougl. ex Loud

At the Millbuie Lodgepole pine intensive provenance plots incrementborings were extracted at similar fractional heights in treesof a central Interior and a southern Coastal provenance andthe properties of the same five growth-rings were compared.Scanning microphotometry was used to measure ring width, percent earlywood, and earlywood density. Tracheid length and width,nominal density, and latewood density were also determined.For each of these wood properties significant differences werefound between the average values for the two provenances. Inthe Coastal provenance nominal density was about 20 per centhigher than in the Interior provenance, the incidence of compressionwood was much higher, but tracheid length was about 20 per centshorter. The probable effects of these results on the propertiesof sawn timber and pulp are discussed. Average tree heightsand diameters were similar, and the earlier growth of the treeswas analysed. The relation between nominal density and ringwidth (vigour) was investigated, and a low correlation (r² of0·054 and 0·17) was found between the two quantities.Furthermore the regression lines show density decreasing slowlywith increased ring width. Both these results are in contrastwith published results for Sitka spruce.