| English | The paper corresponds on the whole with a doctoral thesis of silviculture, presented in 1963 and is a summary of the author's work with the use of herbicides on unwanted hard-wood vegetation. A review of the subject is given, in which among other things older methods of substituting hardwood
by conifers are treated. Different methods of applicating herbicides are described. The author show their use by his own results and by results from investigations in other countries. Results have been presented in the following two papers with summaries in English.
1958. Some exploratory experiments in chemical control of herbaceous and woody plants. - Medd. fr. Statens skogsforskningsinstitut, Band 45, nr 10. (Sw. Sw. e. e.)
1963. Experiments with herbicides 11. - Departm. of Reforest., Roy. Coll. of For., Res. Notes, no. 3 (Sw. Sw. e.)
The main results show:
1. The butoxyethanol ester of 2,4,3-T was, at the basal bark spraying, superior to the butoxyethanolester of 2,4-D on aspen (Populus tremula L.), birch (Betula pubescens Ehrh. and verrucosa Ehrh.), oak (Querqus robur L.) and
hazel (Corylus avellana L.). On aspen and speckled alder, 1-2 m high, the herbicides gave rather equivalent results. Sprouting was efficiently prevented by the method, except on aspen. At stump spraying of birch and hazel, 2,4,5-T prevented sprouting significantly (birch) better than 2,4-D. The herbicides were equivalent on aspen smaller than 5 cm DBH. 2,4,3-T and 2,4-D (triethanol ainine salt) gave equivalent results on the parts above the ground by notching of aspen and birch. On birch 2,4,5-T worked somewhat faster than 2,4-D and prevented sprouting better than 2,4-D. 4K-2M-salt on birch was inferior to 2,4,5-T and 2,4-D. At foliage spraying of aspen and birch 2,4,5-T and 2,4-D gave equivalent results.
2. Basal bark spraying of aspen and hazel gave from a practical point of view equivalent results, either the stems were sprayed up to 0,3 or O,7 111 above the ground.
Stump spraying on birch can be performed with low concentrations even a long time after the cutting. The same results were received on hazel either the stump spraying was made on new stumps or one month after the cutting. Probably the results can be applicated even on other species with sprouting on the upper parts of the root collar and on the stump, parts which are exposed to direct contact with the spray.
3. Diesel oil was superior to water as carrier at basal bark spraying of hazel and stump spraying of birch. The experiments show that a mixture of equal parts of water and diesel oil is applicable on aspen, small dimensions of birch and hazel at basal bark spraying. Because of increased fluid consumption in consequence of smaller wetting ability, the intended profit of the mixture diesel oil-water is small. At stump spraying of birch, diesel oil gave significantly better results as carrier than water. Water can possibly be used as carrier on birch in sites
with more favorable climate without any marked disposition towards vegetative sprouting. Further experiments are necessary to confirm this.
4. The following dosage has been prescribed for notching of birch and aspen: One notch is cut per inch of breast height diameter. A 2,4,5-T or 2,4-D amine containing an acid equivalen of 230 g per litre is applied in each notch for trees up t o 15 cm DBH in size at a rate of 1 cm3 undiluted herbicide. Trees larger than 15 cm at DBH are treated with 1,5-2 cm3 per notch.
5. 2,4,5-T damaged pine (Pinus silvestris L.) considerably less than 2,4-D at direct spraying on seedlings, 0,6-1,O m height, immediately before the growth in the spring. The damages were greater for both the herbicides with diesel oil as carrier. Diesel oil without herbicide caused no damages.
6. No treatment prevented suckering on aspen. Tendencies appear that stump spraying and basal bark spraying of small dimensions of aspen (< 5 cm DBH) have given a smaller number of suckers than foliage spraying. With the last-mentioned method there was no difference between 2,4,5-T and
2,4-D, in preventing the sprouting. Most of the suckers live for a few years, then they die out and are replaced
by new ones. |
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