Articles containing the keyword 'herbicides'

The following treatments were compared in three Scots pine (Pinus sylvestris L.) reforestation areas on a scarified moist mineral-soil site in southern Finland, planted with 1+1 bareroot stock in spring 1987: (a) no weed control treatment; (b) mulching with a fibre slurry produced by mixing wastepaper with water and applied 1 cm deep to an area of 60 cm in diameter around the seedling soon after planting; (c) glyphosate (at 2 kg ha^-1) sprayed on a 1 m² spot around the seedling in early August 1987; (d) terbuthylazine (at 10 kg ha^-1) applied as (c). Monitoring of the trials over a 4-year period between 1987–90 showed that none of the treatments reduced surface vegetation to an extent that would have benefited pine. The percentage cover development of the vegetation, dominated by Agrostis capillaris, Calamagrostis arundinaceae, Deschampsia flexuosa, Festuca ovina, Epilobioum angustifolium and Pteridium aquillinum, followed much the same pattern in all treatments, with (c) slightly favouring forbs. Survival of pine at the end of the study period was about 90%, with non-significant differences between treatments. Mulching and terbuthylazine treatment slightly reduced seedling height growth in the second year. Growth was better in glyphosate treatment than in terbuthylazine treatment in the lowest (<30%) and the highest (>60%) pre-treatment weed cover classes, and in the latter also better than in untreated control. Mulching gave variable results; at its best it provided also good control of weeds for several years, without, however, improving the initial development of pine in these trials.

• Siipilehto, E-mail: js@mm.unknown
• Lyly, E-mail: ol@mm.unknown

Exposure to phenoxy acids and their effect on worker’s health were studied among 35 exposed forest workers. The control group was 47 non-exposed loggers. The both groups were medically examined before and after their working period including such laboratory analyses as B-differential count, B-thrombocytes. In addition, the exposure to eight ULV sprayers and two clearing saw sprayers were measured in breathing zone.

The mean of phenoxy acid concentrations in urine among all the exposed workers after the working period was 6.5 μmol/l being significantly below the hygienic limit value (14 μmol/l). The mean concentrations of ULV sprayer workers was 7.3 μmol/l and of clearing saw sprayer workers 2.7 μmol/l. The mean of air concentrations among ULV sprayers was 0.23 mg/m³ and among clearing saw sprayers 0.06 mg/m³. No statistically significant differences were noticed in the hematologic parameters and in the enzyme activities of the liver, kidney and muscles between the exposed and control groups before or after the working period. So, it seems that these low exposure levels don’t cause sudden changes in health.

The PDF includes an abstract in English.

• Manninen, E-mail: am@mm.unknown
• Heikkinen, E-mail: ph@mm.unknown
• Husman, E-mail: kh@mm.unknown
• Kangas, E-mail: jk@mm.unknown
• Klen, E-mail: tk@mm.unknown
• Mononen, E-mail: im@mm.unknown

The purpose of this study was to measure workers’ exposure to MCPA and glyphosate when sprayers connected to the brush saws was used. A non-pressurized sprayer with a pump and a pressurized sprayer where dosage was regulated with manual control were studied. Exposure was measured from the breathing zone and urine samples.

MCPA collected from the breathing zone gathered into alcohol was 0.05 mg/m³ for the pressurized sprayer, 0.02 mg/m³ for the non-pressurized sprayer, and 0.04 mg/m³ (average) for both types of sprayers together.

MCPA in the breathing zone, collected from splashes and fog into a glass fibre filter, was 0.18 mg/m³ for the pressurized sprayer, 0.09 mg/m³ for the non-pressurized sprayer, and 0.12 mg/m³ for both sprayers used together. Glyphosate in the breathing zone, collected into sodium hydroxide was below 0.05 mg/m³.

In five urine samples taken after the work day there was on the average 0.4 mg/l MCPA, while in 21 samples the MCPA contents were under the definition limit (0.2 mg/l).

The PDF includes a summary in Finnish.

• Kangas, E-mail: jk@mm.unknown
• Klen, E-mail: tk@mm.unknown

The applicability of MCPA- and 2,4,5-T-herbicides for use in the management of sapling stands and the possibilities of carrying out foliar spraying at an earlier date than at precent with smaller doses of the active ingredient were examined in this study. The results were obtained from foliage spraying experiments carried out in Central Finland in summer 1976. MCPA and 2,4,5-T were as effective as each other against deciduous tree species. However, MCPA was slightly more effective against aspen (Populus tremula L.) than 2,4,5-T. The spraying date had no effect on the mortality rate of aspen or birch (Betula pendula Roth and B. pubescens Ehrh.) There were only very slight differences between the results for different dosage levels. The damage caused to Scots pine (Pinus sylvestris L.) was very slight. The temperature conditions prevailing during spraying affected spraying effectiveness in such way that the mortality rate decreased during cold period.

The PDF includes a summary in English.

• Meriluoto, E-mail: jm@mm.unknown

In most pine swamp stands on drained peatlands the dwarf-shrubs are rather important biomass producers. The aim of the experiment was to determine the effect of killing off the dwarf-shrub vegetation on the subsequent development of Scots pine (Pinus sylvestris L.) stand. The dwarf-shrub vegetation was killed by means of herbicides. The results show that by removing competition by the dwarf-shrub vegetation on drained pine swamps, it is possible to pass onto the trees at least some of the freed growth potential.

The PDF includes a summary in Finnish.

• Sarasto, E-mail: js@mm.unknown
• Seppälä, E-mail: ks@mm.unknown

The apparent toxicity of soil-incorporated monuron, picloram, CDEC, EPTC, CDAA, and sesone to young Pinus resinosa Ait. seedlings was studied over a temperature range of 10–30 °C in growth chambers. The herbicides were first applied to the surface of autoclaved soil at 1 1b/A and later mixed into the soil. Thereafter pine seeds were planted and subsequent seedling development was studied. The effect of CDEC, EPTC, CDAA, and sesone were also studied at dosages of 2 and 3 1b/A (soil surface basis).

Under the conditions of this study, picloram and monuron were persistent in the soil and toxic to pine seedlings, whereas CDEC, EPTC, CDAA, and sesone appeared to be non-toxic. However, the apparent lack of phytotoxicity of the latter group apparently was caused largely by lack of activation of sesone by autoclaving soil and large losses from the soil of CDEC, EPTC, and CDAA even before seeds were planted.

High toxicity of picloram and monuron was showed by reductions in seedling survival, total dry weight increment of plants, and dry weight increment of surviving seedlings. Various temperature regimes greatly affected growth of herbicide treated plants and controls. In control plants both high and low temperatures adversely affected seedling survival and dry weight more than shoot growth. Temperature extremes generally inhibited root growth more than shoot growth. The high temperatures, 25 and 30 °C, markedly enhanced phytotoxicity of picloram and muron.

The PDF includes a summary in Finnish.

• Kozlowski, E-mail: tk@mm.unknown
• Sasaki, E-mail: ss@mm.unknown
• Torrie, E-mail: jt@mm.unknown

Silva Fennica Issue 80 includes presentations held in 1952 in the 7th professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes a field experiment on the use of herbicides to prevent growth of ground vegetation in cutting areas before sowing. The study suggests that the chemicals used in the experiment were not effective enough to prevent growth of ground vegetation in the more fertile lands, but were effective in poorer lands. However, the treatment affected also growth of tree seedlings.

• Paavola, E-mail: ep@mm.unknown

An attempt was made in the study to determine the annual periods available for foliage spraying when cleaning Scots pine (Pinus sylvestris L.) dominated seedling stands. The study was made in nine experimental fields which were established in different parts of Finland. The spraying was applied throughout the growing season by DM, MCPA and Roundup. The results were inventoried one year after the treatments.

The results showed that there were big differences both in the destruction of hardwood sprouts and in the survival of pine seedlings due to the time period of the spraying. Threshold points were observed in the range of effect of DM and MCPA. By means of these it is possible to time the spraying treatments in such a way that there remains only slight damage to pine, but hardwood sprouts are destroyed totally. The results varied with Roundup so much, among other things due to rain, that such threshold points could not be determined. This preparation both had a milder effect on the hardwood seedlings and caused slighter damage to pine than the other preparations.

In Sodankylä in Northern Finland, the pines attained a good resistance to arboricides when the efficient temperature sum of the growing season was 550, but in Punkaharju in Central Finland only when it was 850. The seed provenance of the seedlings had an effect on the resistance. The threshold temperature sums of resistance in pine were on the average 70–74% from the long-term average number of degree days at the origin of the seed. The effect on the hardwood trees grew weaker as the long-term average was filled. Resistance of pine followed with a specific lag the lignification of the shoot and the ceasing of the growth of the needles.

The PDF includes a summary in English.

• Pohtila, E-mail: ep@mm.unknown
• Pohjola, E-mail: tp@mm.unknown

• Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: jyrki.hytonen@metla.fi
• Jylhä, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: pj@nn.fi

• Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FIN-69101 Kannus, Finland E-mail: jyrki.hytonen@metla.fi

• Juntunen, The Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: marja-liisa.juntunen@metla.fi