Effects of deicing salt on eastern white pine (Pinusstrobus L.) were studied in the field and in the laboratory. Studies in controlled temperature chambers showed that solutions of deicing salt sprayed onto 4-year-old trees induced symptoms of foliar browning similar to those observed on trees growing near highways. Symptoms developed at 15 °C but not at 1.5 °C. The amount of injury that developed after 3 weeks at 15 °C appeared to be directly related to the concentration of sodium and chloride in the leaf tissue. Repeated sampling of foliage from trees adjacent to highway 401 between May 1970 and May 1971 revealed that foliar concentrations of sodium and chloride declined from abnormally high values (up to 1%) in May to 'normal' levels (0.02–0.1%) by August. The rate of loss was proportional to the foliar concentration of these ions. Growth of these trees, measured as bud weight, needle length, needle dry weight, needle bundles per leader, and leaf length, was suppressed on the side of trees exposed to the highway, but this suppression diminished as distance from the highway increased. Annual radial increments to the trunk were appreciably smaller in trees close to the highway than in trees further away. These results support the concept that deicing salt spray injures leaves and reduces growth of eastern white pine growing adjacent to highways that receive deicing salt in the winter.

Purvis, P., Chong, C. and Lumis, G. P. 2000. Recirculation of nutrients in container nursery production. Can. J. Plant Sci. 80: 39-45. This study evaluated (a) the capacity of a computerized injector to deliver and recirculate nutrients in a container nursery, and (b) plant growth and nutrient status under this regime compared with non-recirculated methods of fertilization, using Dart's Gold ninebark (Physocarpus opulifolius L. 'Dart's Gold') potted in 6-L containers filled with a medium of pine bark, peat, and soil (75, 15, and 10%, by volume). The injector was programmed to deliver NH 4 -N (24 mg L -1 ), NO 3 -N (196 mg L -1 ), P (54 mg L -1 ), and K (235 mg L -1 ) and other nutrients, with or without recirculation. Plants grown with recirculated nutrients were placed on aluminium troughs to collect the leachate, which was pumped back to the injector, recharged [based on a target electrical conductivity (EC) value of 1.85 dS m -1 ], and returned to the crop. Additional plants were grown on a crushed stone base and fertilized (a) by the computerized injector without recirculation, (b) with water soluble Plant-Prod 20-8-20 (200 mg L -1 N; non-recirculated) delivered through a Dosatron proportioner, or (c) with incorporated, controlled release Nutricote 18-6-8, Type 140 (6.5 kg m -3 ). NH 4 -N, NO 3 -N, P, and K concentrations delivered by the computerized injector (recirculated and non-recirculated; mean over six dates, 3 July to 28 August 1997) were 50, 22, 41, and 39%, respectively, lower than targeted values. Electrical conductivity values were not significantly different from targeted. The pH values (6.2 -6.4) were higher than targeted (6.0). The amounts of N, P, and K used were reduced by between 57 and 77% with recirculation compared to without. Notwithstanding reduced N, P, and K values, plants grew best with recirculated nutrients and least with non-recirculated liquid 20-8-20. 18-6-8, type 140 (6,5 kg M -3 ). Les concentrations de N ammoniacal et nitrique, de P et de K distribuées par l'injecteur (avec ou sans recyclage) étaient respectivement en moyenne (six dates échelon-nées du 3 juillet au 28 août 1997) de 50, 22, 41 et 39 % plus basses que les valeurs attendues. Les valeurs CE en revanche ne s'é-cartaient pas significativement des valeurs cibles mais les valeurs pH (6,2 à 6,4) étaient plus élevées que la valeur ciblée (6,0). Les quantités de N, P et K utilisées étaient diminuées de 57 à 77 % en circuit recyclé, mais malgré cela la meilleure croissance était obtenue avec les fertilisants recyclés. C'est la solution 20-8-20 sans recyclage qui produisait la croissance la moins bonne.

To minimize fertilizer and water use, and NO3-N runoff from container culture, growth, and nutrient status of forsythia (Forsythia ×intermedia Zab. ‘Spring Glory’) in No. 2 containers were compared in response to a controlled-release fertilizer (CRF; Nutricote 18-6-8 100-day at rates of 2, 4, and 6 kg·m−3) and placements (incorporation and topdress) under three irrigation strategies [drip-irrigated low (25% or less) leaching fraction (DrLoLF), hand-sprinkled low leaching fraction (HsLoLF), and hand-sprinkled high (50% or less) leaching fraction (HsHiLF)]. In a coexperiment under drip irrigation only, forsythia response was also examined under incorporation, topdress, and dibble fertilizer placements with the same CRF rates applied as single or split dose. Dibble fertilizer placement was superior to both incorporation and topdress in this order. Maximum growth of forsythia occurred at rates of 4.7 kg·m−3 with dibble. With incorporation and topdress, maximum growth was not achieved even at the 6 kg·m−3 maximum rate tested. Forsythia grew better with incorporated than with topdressed CRF with the DrLoLF treatment. The response was reverse with HsHiLF or showed no differences with HsLoLF. Under drip irrigation, greater concentrations of NO3-N generally leached from incorporation and dibbled containers in this order than from topdress. Less nitrate was leached from the topdressed containers because less was released from the CRF prills. At the 6 kg·m−3 CRF rate, total cumulative NO3-N leachings were 76, 85, and 22 kg·ha−1 (45 × 45-cm container spacing) for dibbling, incorporation, and topdress, respectively, under drip irrigation. Split application of CRF greatly reduced NO3-N in leachate, although plant growth also was reduced as a result of less availability of and uptake of nutrients under this strategy.

Chong, C. and Lumis, G. P. 2000. Mixtures of paper mill sludge, wood chips, bark, and peat in substrates for pot-in-pot shade tree production. Can. J. Plant Sci. 80: 669-675. There is little scientific information on substrates for pot-in-pot shade tree production. The objective of this research was to examine various organic-waste-derived substrates for growing shade trees in potin-pot systems. Seedling whips of green ash (Fraxinus pennsylvanica Marsh.), Japanese birch [Betula platyphylla var. japonica (Miq.) Hara], and silver maple (Acer saccharinum L.) were grown for two seasons in 76-L containers. The containers were trickle irrigated and fertilized with controlled-release fertilizers. Treatments included a control nursery mix (50% by volume of pine bark:15% compost:35% topsoil) and nine other mixes classified into three groups: Group I (25, 50 or 75% bark mixed with 50, 25, or 0% wood chips, and 25% paper mill sludge); Group II (25, 50 or 75% bark; 50, 25 or 0% wood chips; and 25% peat); and Group III (25, 50 or 75% peat; 50, 25 or 0% wood chips; and 25% paper mill sludge). In both years, trunk diameters of the three species were greatest with Group III substrates, intermediate with Group II, and least with Group I. Trunk growth was positively correlated with water retention porosity, which ranged from 42 to 57%, 38 to 42%, and 20 to 27% for Groups III, II, and I, respectively. Trunk diameters of Group II and III trees were equal to, or slightly exceeded (10-12%), those of the nursery mix. The nursery mix had a water retention porosity of 49% and generally the highest content of soluble salts. The high-peat (50 and 75%) substrates marginally but consistently produced trees with the largest trunk diameters, although with birch (not the other species) shorter trees resulted as the peat content increased. de 25, 50, 25; 50, 25, 25 ou 75, 0, 25 %. Dans les deux années, le diamètre des troncs chez les trois espèces atteignaient les valeurs les plus hautes avec les substrats du Groupe III, les valeurs intermédiaires avec ceux du Groupe II et les valeurs les plus basses avec celles du Groupe I. La croissance du tronc était positivement reliée à la porosité de rétention de l'eau, laquelle allait de 42 à 57, 38 à 42 et 20 à 27 %, respectivement, dans les milieux des groupes III, II et I. Le diamètre du tronc des arbres des Groupes II et III était égal ou légèrement supérieur (10-12 %) à celui des arbres cultivés dans le substrat témoin, qui avait une porosité de rétention de 49 % et qui, en général, contenait le plus de sels solubles. Les substrats à forte proportion (50 et 75 %) de tourbe produisaient les arbres possédant les diamètres de tronc légèrement, mais régulière-ment, les plus grands, bien que la taille des bouleaux diminuait à mesure qu'augmentait la proportion de tourbe dans le mélange.

Luurs, G. P., Hopsrne, G. nNo He.ll, R. 1976. Roadside For personal use only.