The use of electrolytic conductivity as a measure of cell membrane disruption was tested on buckwheat (Fagopyrum esculentumMoench. cv. ‘Tokyo’) plants which had been sprayed with paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. All treatments which resulted in tissue damage caused significant increases to the solutions where the discs were floated for measurement. The highest conductivity measurement (most membrane disruption) was obtained from paraquat. The highest concentration for each herbicide gave higher conductivity measurements than lower concentrations. A difference in the pattern of conductivity change induced by the two chemicals implies a different mode of action for each.

Herbicidal activity of foliar-applied oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] was light dependent in buckwheat (Fagopyrum esculentumMoench. ‘Tokyo’). Plants were not injured when placed in the dark for as long as 4 days after herbicide treatment. When these plants were brought to the light, injury occurred, albeit more slowly than when plants were placed in the light immediately after treatment. The rate of injury increased as light intensity increased. The most effective wave length was 565 to 615ηm, suggesting the involvement of a pigment with its absorption spectrum in this region. Chlorophyll content was not reduced by oxyfluorfen. Preliminary evidence suggests that photosynthesis was affected only after membrane integrity was disrupted.

Herbicides were tested for control of volunteer Jerusalem artichoke in 1977. Glyphosate at 1.0 and 2.0 kg a.i./ha and dicamba plus 2,4-D plus mecoprop at 0.6 and 1.2 kg a.i./ha gave commercially acceptable control throughout the growing season. 2,4-D, MCPA, and paraquat at 0.6 and 1.2 kg a.i./ha gave unacceptable control.

Root uptake and translocation of nitrofluorfen [2-chloro-1-(4-nitrophenoxy)-4-(trifluoromethyl)benzene] and oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] were measured in fababean(Vicia fabaL.) and green foxtail [Setaria viridis(L.) Beauv.] plants, and metabolism was studied using fababean leaf discs and green foxtail leaf segments. Both herbicides were taken up readily from nutrient solution but translocation was limited. In fababeans, 4.6% of the nitrofluorfen label was translocated to the shoot as compared to 2.2% of the oxyfluorfen label. Less than 10% of the nitrofluorfen or oxyfluorfen taken up in vitro was metabolized after 24 h. This rate of metabolism would not likely influence the herbicidal action of either herbicide.

crops is encouraging new growers who may be untrained in nurserycrops propagation to begin nursery production. Contributions by H. J. M. Temmerman and H. Hiebert, and by former staff of the Morden Research Station are gratefully acknowledged. The authors also wish to thank the staff at the Provincial Tree Nursery, Oliver, Alta., and the Prairie Farm Rehabilitation Administration, Indian Head, Sask., for reviewing this publication and suggesting improvements. Seed propagation Each seed produces an entirely new plant. Seedlings produced from seeds of the same seed lot differ from one another, just as people do. Most plant materials that have been improved ornamentally, particularly through interspecific hybridization, cannot be propagated from seed because seedling variation is too great. Improved nursery cultivars that were selected for disease resistance, double flowering habit, unusual leaf color or shape, quality of fruit, particular tree form, and other improved characteristics fall into this group. About 45% of the nursery plants sold on the prairies are propagated as seedling material. Also, many seedlings are propagated and used as rootstocks for budding and grafting. When they are used in this way, all should be uniformly vigorous and healthy but they do not need perfect uniformity of ornamental characters. Collection Seedling growers may collect their own seeds or may buy them commercially. A seed that is adapted to your growing area is essential, because some species grow over a vast continental area in which climatic conditions can vary dramatically. Green ash, for instance, is native from Florida to northern Saskatchewan; the southern sources for seeds produce seedlings that, on the prairies, winter-kill to the snow line, whereas seeds from northern, prairie sources are adapted to the climatic conditions of the Prairie Provinces. Seeds must therefore be collected from a location similar in climate and latitude to the one in which the plants will eventually be grown. Seeds from a nearby location will produce seedlings that are genetically adapted to the climatic conditions imposed on them; seeds from other geographical areas of similar latitude and climate may also produce adapted seedlings. Latitude is especially important in seed collection, because the onset of winter hardening is triggered, in part, by decreasing day length, which varies with the latitude. In general, a seedling should not be grown more than 500 km north of the location in which the seed was collected. Altitudinal differences can also cause problems, and therefore variations of more than 1000 m elevation are not recommended.