Absorption and translocation of glyphosate [N-(phosphonomethyl)glycine] with and without adjuvants were examined in field bindweed (Convolvulus arvensisL. # CONAR) to develop an understanding of the influence of selected adjuvants and environment before application on glyphosate activity. Light intensity and humidity during plant development resulted in differences in14C-glyphosate absorption. When applied in water or with an oxysorbic (20 POE) (polyoxyethylene sorbitan monolaurate) adjuvant, an average of 9% of the glyphosate was absorbed in plants grown in high light intensity, low humidity (HLLH) before treatment, compared to an average of 21% in plants grown in low light, high humidity (LLHH) before treatment, respectively. Amounts of epicuticular wax on HLLH field bindweed were almost three times as great as on LLHH leaves and may explain absorption differences. No differences in glyphosate absorption were observed between glyphosate applied with oxysorbic or no adjuvant even though the oxysorbic adjuvant effectively reduces surface tension. Absorption was increased two- to threefold with a polyethoxylated tallow amine adjuvant (MON 0818) compared to no adjuvant. Unlike absorption without adjuvant or with oxysorbic adjuvant, there were few absorption differences in plants grown in different environments before application. Absorption continued for 24 to 36 h after application regardless of adjuvant. Reductions in MON 0818 concentration and subsequent necrosis resulted in increased movement of radioactivity away from the site of application.

To develop an understanding of how adjuvants might enhance glyphosate [N-(phosphonomethyl)glycine] activity, absorption and translocation of a polyethoxylated tallow amine amphoteric surfactant (MON 0818) were examined in field bindweed (Convolvulus arvensisL. # CONAR). Scanning electron microscopy did not reveal any physical disruption of the epicuticular waxes from spray applications of MON 0818, an oxysorbic (20 POE) (polyoxyethylene sorbitan monolaurate) surfactant, or glyphosate. Radioactive MON 0818 absorption was rapid during the first 6 h. Maximum absorption (84%) occurred by 24 h after application. Less than 3% of the applied radioactivity was recovered from the epicuticular wax of treated leaves. Movement of radioactivity away from the treated area was limited predominantly to movement within the treated leaf. Altering light intensity or humidity in which the plants developed before treatment did not influence MON 0818 absorption.

1981. Paraquat influences development and efficacy of the mycorrhizal fungus Glomus fasciculatus. Can. J. Bot. 59: 5 18-521.Paraquat (1,l-dimethyl-4,4'-bipyridinium chloride) applied at 2 kglha significantly reduced the amount of mycorrhizal hyphae and number of vesicles and chlamydospores formed by Glomus fasciculatus (Thaxt.) Gerd. and Trappe when compared with the control or the 0.5 kglha paraquat treatment. When compared with inoculated control, paraquat applied at 0.5 kglha tended to increase the amount of mycorrhizal hyphae, and significantly increased chlamydospore production. For noninoculated white ash (Fruxinus americana L.) seedlings, total dry weight and stem height tended to decrease with increases in rates of paraquat applied. In contrast, seedling height and foliar P concentration of inoculated seedlings tended to be greatest for the 0.5 kglha paraquat treatment followed by the control and the 2 kglha chemical treatment. The amount of mycorrhizal hyphae was significantly correlated to seedling height and diameter, total dry weight, and percentage foliar elemental P. POPE, P. E., et H. A. HOLT. 1981. Paraquat influences development and efficacy of the mycorrhizal fungus Glomus fasciculatus. Can. J. Bot. 59: 518-521. Le paraquat (chlorure de 1,l-dimethyl-4,4'-bipyridinium), appliquC a une intensit6 de 2 kglha, rCduit significativement la quantitC d'hyphes mycorhiziens et le nombre de vCsicules et de chlamydospores formCes par Glomus fascic~(1atus (Thaxt.) Gerd.& Trappe, par comparaison avec les tCmoins ou avec les traitements de paraquat i 0,5 kglha. Par rapport au tkmoin inoculC, le paraquat a 0,5 kglha a tendance a augmenter la quantitC d'hyphes mycorhiziens et accroit significativement la production de chlamydospores. Chez les plantules non inoculCes de fr&ne blanc (Fruxinus americana L.), le poids sec total et la hauteur de la tige ont tendance i diminuer avec l'augmentation du taux d'application du paraquat. Au contraire, la hauteur des plantules et la concentration foliaire du phosphore chez les plantules inoculCes ont tendance i &tre plus grandes pour le traitement de paraquat a 0,5 kglha, suivies par le tCmoin, puis par le traitement a 2 kglha. La quantitk d'hyphes mycorhiziens est significativement corrClCe avec le diamktre et la hauteur des plantules, avec le poids sec total et avec le pourcentage du phosphore ClCmentaire dans les feuilles.[Traduit par le journal]

Trees converted from round-over to V-trims could develop a canopy of potentially weak watersprouts growing on parent stems with a high probability of decay. This study was conducted to determine if the conversion from round-over to V-trimming predisposes silver maple (Acer saccharinum L.) trees to failure, and if decay is more likely to occur in watersprouts arising after heading cuts than in branches arising from lateral buds. Watersprouts were mechanically pulled from converted trees and found to be 49% weaker than normally occurring branches. Branch strength at failure (stress) decreased as watersprouts grew in size, and decay was present in over one-half of the watersprout at the point of failure. The conversion from round-over to V-trimming appears to predispose silver maple trees to failure.

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