Der Faktor der Biozönose in den Tollwutepizootien

Summary It is stated that in the spreading of epizooties among small wild animals, a factor of biocoenosis played a main role, first of all some phenomena among small rodents, the field mice. In the spreading of rabies infection, a role is ascribed to an insect, theNecrophorus vespillo.The author suggests a research work to be done in that respect, and perhaps in the regions where rabies was never registered and are still free of rabies, as to establish what in a such biocoenosis is lacking that could be a factor of rabies epizooty.

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Résumé A l'extension de grandes épizooties chez les animoux féroces, on considère que le grand rôle joue le facteur de biocenose, tout d'abord certains phénomènes entre les menus rongeurs, souris de champs. On attribute surtout le rôle de l'extension de l'épizootie de rage à l'insectNecrophorus vespillo. On recommende de faire des recherches dans ce but avec les autres branches de sciences naturelles et peut-être dans ces regions du monde où il n'y en avait pas et il n'y a pas aujourd'hui de rage, pour établir ce qu'il manque dans une telle biocenose et que peut être pourrait on prendre en considération comme le facteur des épisooties de rage.

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, — . Necrophorus vespillo L. . , .

     

Auftreten und Bedeutung der Salatwarzellaus (Pemphigus bursarius [L.]) als Schäling an Kopfsalat

Zusammenfassung Die SalatwurzellausPemphigus bursarius (L.)(Aphidoidea, Pemphigidae) gehört wegen ihrer unterirdischen Lebensweise zu den schwer bekämpfbaren Schädlingen, die in Salatkulturen regional starke Schäden verursachen können und von zunehmendem Interesse sind. In einem Befallsgebiet in Wolfenbüttel bei Braunschweig werden daher mehrjährige Untersuchungen zur Ermittlung der Bedeutung und geeigneter Bekä mpfungsmöglichkeiten der Salatwurzellaus durchgeführt. Bisher können über das Auftreten und die Bedeutung dieses Schädlings folgende Aussagen gemacht werden: Es besteht kein ursächlicher Zusammenhang zwischen dem Auftreten der Salatwurzellaus und zweier Salatvirosen (Salatmosaikvirus und Gurkenmosaikvirus). Sie alle traten unabhängig voneinander auf. Im Untersuchungsgebiet überwintertP. bursarius ausschließ lich an Pappeln, nicht dagegen im Ackerboden oder an Wurzelresten. Die Anfälligkeit verschiedener Salatsorten gegenüberP. bursarius ist nach den bisherigen Ergebnissen an 30 Sorten recht unterschiedlich, wobei die Sorten Hilmar, Kordaat, Unico, Kloek, Viktoria und Winter Butterkopf einen geringen oder gar keinen Befall zeigten, während die Sorten Wunder von Voorburg, Kagraner Sommer und Winter Mombacher stark befallen wurden. Diese Versuche müssen weitergeführt werden, bevor eine abschließende Beurteilung möglich ist. Die Schäden durch die Virosen, speziell das Salatmosaikvirus, sind in den Salatkulturen wesentlich schwerwiegender als die durchP. bursarius verursachten Verluste. Über Bekämpfungsversuche wird später berichtet.

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Summary The lettuce root AphidPemphigus bursarius (L.)(Aphidoidea, Pemphigidae) belongs to the difficult controlable pests because of their subterranean mode of life. In lettuce cultures of certain regions this aphid can cause serious damages and therefore it is of increasing interest. In an area severely attacked byP. bursarius at Wolfenbü ttel near Braunschweig investigations are going on for several years to get to know the importance of this insect and to find out appropriate possibilities for its control. Up to now the following statements can be made concerning the appearance and the importance of this pest: There is no causal association between the lettuce root Aphid and two viroses of lettuce (lactuca virus 1 and cucumis virus 2). These pests appear independent from each other. In the investigated areaP. bursarius does hibernate only on poplars but not in the soil or on remaining roots. According to the hitherto existing results of 30 lettuce sorts the susceptibility of the various sorts againstP. bursarius is very different. The sorts Hilmar, Kordaat, Unico, Kloek, Viktoria and Winter Butterkopf did show a low or no attack, during the sorts Wunder von Voorburg, Kagraner Sommer and Winter Mombacher were severely attacked. These experiments must be continued before a definitive decision is possible. The damages in the lettuce cultures caused by the viroses, especially by lactuca virus 1, are more serious than those caused byP. bursarius. The control experiments are reported later.

     

Predicting field performance using seedling quality assessment

Seedling quality is defined as fitness for purpose. Attributes for assessing seedling quality are grouped in material attributes that can be rapidly assessed by any number of direct or indirect methods, and performance attributes that are assessed by subjecting whole seedlings to certain environmental regimes and evaluating their growth response. Material attributes comprising morphology, bud dormancy, water relations and nutrition and performance attributes comprising frost hardiness, vigour and root growth potential are discussed with regard to relevance for predicting field performance. Measurement techniques and relevance in assessing seedling quality are presented for different physiological attributes: electrolyte leakage, enzymatic activity, water potential, water conductance, mineral nutrition, food reserves, mitotic index, gas exchange, chlorophyll content, plant growth regulators, stress-induced volatile emission, and nuclear magnetic resonance. Methods with future potential in improving the prediction of field performance are identified and discussed. The methods presented in this respect are chlorophyll fluorescence, infrared thermography, machine vision systems, integrated approaches and ecophysiological evaluations.     

Schäden durch Blattälchen (Aphelenchoides ritzemabosi) anFicus elastica undRodgersia aesculifolia

Zusammenfassung Aphelenchoides ritzemabosi wurde erstmals auch anFicus elastica undRodgersia aesculiformis nachgewiesen. Schäden und typische Befallssymptome werden beschrieben und abgebildet. Die Infektion erfolgte wahrscheinlich durch Erde, in der im Jahr zuvor Chrysanthemen wuchsen, die vonAphelenchoides ritzemabosi befallen waren.

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Summary Aphelenchoides ritzemabosi has been recognised for the first time atFicus elastica andRodgersia aesculiformis too. Damages and typical symptoms of affected leaves are described. The infections atFicus elastica probably were due to the earth in which the year before grew Chrysanthemum attacked byAphelenchoides ritzemabosi.Samenvatting Aphelenchoides ritzemabosi werden voor het eerst ook vastgesteld aanFicus elastica enRodgersia aesculiformis. De schade en de typische symptomen van de aangevallen bladeren wordt beschreven. De infecties aanFicus elastica zijn waarschijnlijk te wijten aan de aarde in welke het jaar daarvoor Chrysanthemum groiden, die doorAphelenchoides ritzemabosi aangevallen waren.

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Résumé Aphelenchoides ritzemabosi était constaté premièrement auxFicus elastica etRodgersia aesculiformis. Des dommages et des symptomes typique aux feuilles affectées sont déscrits. Les infections auxFicus elastica sont dues probablement à la terre dans laquelle l'année passée étaient planté des Chrysanthèmes saisis parAphelenchoides ritzemabosi.

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(Aphelenchoides ritzemabosi) (Ficus elastica) (Rodgersia aesculiformis). . (Aphelenchoides ritzemabosi).

     

Zur Wirkung von Sevin auf Regenwürmer

Zusammenfassung In Freiland- und Laborversuchen wurde die Wirkung des Pflanzenschutzmittels Sevin auf Regenwürmer untersucht. Dieser Stoff ist in Pulverform und als Suspension für diese Organismen außerordentlich gefährlich. Schon der Kontakt mit sehr geringen Mengen bewirkt schwere Lähmungserscheinungen und irreversible histopathologische Schäden.

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Summary Experiments in the field as well as in the laboratory showed up the effect of the pesticide Sevin on rainworms. In the form of powder as well as a suspension this material is extremely toxic for them. Contact with smallest quantities even causes severe paralysis and irreversible histopathologic damages.

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Résumé Aussi bien dans la nature que au laboratoire nous avons étudié l'activité de l'insecticide Sevin sur les vers de terre. Ce produit est en poudre ou en suspension extrémement dangereux pour ces organismes. Le seul contact avec des quantités minimes de ce produit provoquent des phénomènes de paralysie et des troubles histopathologiques irreversibles.

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SEVIN . . .

     

Dormancy induction in container-grown Abies seedlings: Effects of environmental cues and seedling age

Twelve-week-old container-grown seedlings of noble fir (Abies procera Rehd.) and Shasta red fir (A. magnifica A. Murr. var. shastensis Lemm.), both high-elevation species, were grown under controlled environments in a study of induction of terminal-bud dormancy. Eight treatment combinations of long (15 h) or short (11 h) photoperiods, warm (25°/20°C) or cool (18°/12°C) thermoperiods, and dry (–1.2 MPa) or wet (–0.6 MPa) moisture regimes were imposed upon seedlings for 12 weeks. Treatment factors significantly affecting the induction of dormancy in terminal buds of seedlings were identified over time. The results suggest that seedlings responded dynamically to dormancy cues. The warm/dry and cool/wet combinations induced dormancy in the first 2 weeks in noble fir and in the first week in Shasta red fir. Short-day/warm and long-day/cool combinations enhanced dormancy induction in weeks 3 to 4 in noble fir and in weeks 1 to 7 in Shasta red fir. Short days and cool thermoperiods independently hastened dormancy induction in noble fir in weeks 5 through 12.     

Water circulation, groundwater outflow and nutrient dynamics in Mida creek, Kenya

The relationship between physical hydrodynamic processes and nutrients dynamics was investigated in Mida creek, a groundwater influenced mangrovefringed creek in Kenya between March 1996 and May 1997. The research involved spot and timeseries measurement of nitrate–nitrite, ammonia, silicates, phosphates, salinity, temperature, sealevel as well as tidal currents at seven stations located in the front, middle and backwater zones of the creek. Groundwater level as well as total dissolved solids' concentration, salinity, temperature and nutrients' concentration were also measured once every month in shallow wells (watertable<5m) located in the upper region of the creek. Results of the study show that nutrient concentrations vary with the tide and that, though there is no river drainage, they are of the same magnitude as in mangrove creeks with substantial river runoff. The peak concentrations of NH ₄ ⁺ –N (5.45M), NO ₂ –NO ₃ (5.63M), PO ₄ ^3– –P (0.58M) and SiO ₃ ^2– –Si (81.36M) in the creek occurred during flood tide, 2–3h before high waters. The (NO ₂ ^– + NO ₃ ^– )–N concentrations declined rapidly during ebb tide, reaching the minimum levels during low water. Contribution of groundwater seepage to the net nutrients flux (particularly on nitrite–nitrates) is largest in dry seasons. The study shows that groundwater outflow sustains the mangroves during periods of severe salinity stress and nutrients deficiency in dry seasons. This is essentially by limiting salinity increase and by boosting nutrient supply in dry seasons.     

Samenschädlinge der Laubhölzer in der zentralen Ukraine und einige Faktoren,welche ihre Widerstansfähigkeit gegen Schädinsekten bestimmen

Zusammenfassung Samenuntersuchungen an 12 Eichenarten und -formen, 20 Birkenarten und 14 Ahornarten zeigten, daß die Samen der Eichen und Ahorne, nordamerikanischer Birken und Ahorne nordasiatischer Abstammung in der Ukraine praktisch von Schädinsekten nicht beschädigt werden, während der Samenertrag der heimischen durch Schadinsekten stark herabgemindert wird.Die Widerstandsstärke der Samen gegen Schädlinge ändert sich. nicht nur bei den verschiedenen Arten, sondern auch innerhalb der Bäume einer Art je nach ihrem physiologischen Zustand. Die Widerstandsfaktoren der Samen gegen Schädinsekten sind entweder anatomisch-morphologische Besonderheiten (Schalenstärke), oder das Vorhandensein von Schutzstoffen in den Samen oder beide zusammen. Besonders deutlich sind diese Faktoren in den Eicheln von Bäumen der nordamerikanischen Abstammung gegen Eichelrüssler ausgeprägt. Chromatographische Analyse der Auszüge aus den widerstandsfähigen Samen der Schmidt'schen Birke und des Eschenahorns zeigten, daß für die Rolle der Schutzstoffe die Phenolstoffe verantwortlich sind von denen z. B. die Chlorogensäure ermittelt wurde.

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12 , 20 14 - , - , - - . . - / /, . - . , , , , .

     

Kurzer Beitrag zur Zucht desTribolium destructor

Summary In this paper a new method for rearingTribolium destructor is described. For oviposition the imagines are cultured in a thermostate (27° C, 70% RH) on a mixture of flour and yeast; additional feeding of pieces of fresh apple is necessary. The sifted eggs also must be stored in the thermostate. The newly hatched larvae must be isolated from the mixture of egg shells, particles of yeast, excrements of the beetles and of the remains of flour, and they get fresh food (flour-yeast-mixture). The rearing is performed in the thermostate in glass-vessels of a bigness corresponding to the developmental state of the larvae. Fully grown larvae must be isolated (for getting exactly dated material of pupae) or they are put in Petri-dishes furnished with fluted coardboard. Pupae and imagines which are not used for obtaining eggs are cultured at room temperature in darkness (flour-yeast-mixture with additional feeding of apple pieces).

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Résumé Dans ce travail une nouvelle méthode de l'élevage deTribolium destructor est décrite. Pour la déposition des oeufs les adultes sont tenus dans un thermostat à température constante (27° C et 70% RH) dans une mixture de farine et de levure; en outre il faut un don supplémentaire de pomme fraî che. Les oeufs séparés en criblant sont aussi tenus dans le thermostat. Les larves qui viennent d'é clore sont à séparer de la mixture des coques d'oeuf, des particules de levure, des excréments et des restes de farine, et après elles reçoivent de la nourriture fraîche (mixture de farine et de levure). L'élevage a lieu dans des bocaux dans le thermostat. La grandeure de ces bocaux doit correspondre à l'état du développement des larves. Les larves complétement développées sont à isoler (pour obtenir du materiel des chrysalides bien datées) ou à mettre dans des bocaux »Petri« fournis de carton ondulé. Les chrysalides et les adultes, qui ne sont pas nécessaires pour la déposition des oeufs, sont á tenir à témperature de chambre dans l'obscurité (mixture de farine et de levure, de temps en temps aussi de pomme).

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» «Tribolium destructor Uyttenb.). 27° C 70% PH ; . . , , ; ( ). , . ( « »-, ). , ( — , ).

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Diese Untersuchung wurde im Zusammenhang mit einem größeren Forschungsvorhaben durchgeführt, das durch Unterstützung der Deutschen Forschungsgemeinschaft ermöglicht wird.     

Versuche zur Bekämpfung der ObstbaumspinnmilbePanonychus ulmi Koch im Libanon

Summary During the application of several acaricides to manifest their effectivness againstPanonychus ulmi Koch living on the apple trees in Lebanon, it could be clearly noticed that a kind of resistance to the phosphoric acid organic preparations occurs, where these mentioned chemicals are regularly used against the mites. The control succes by means of some acaricides and ovicides combinations is here discussed. AsTetranychus urticae Koch in some apple plantations infests the different weeds growing together with the trees there and it wanders in summer to overrun the apple trees; the question of the mite control by means of respective sprays or by means of weed eradication is also discussed.

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Résumé L'étude de l'efficacité d'une série d'acaricides dePanonychus ulmi Koch sur pomme en Liban a démontré une certaine résistance de groupes des parathions, lá où ceux — ci sont appliqués régulièrement depuis des années. Les résultats de combat de quelques acaricides et combinaisons par des ovicides sont discutés. PuisqueTetranychus urticae Koch occupe les herbes, les plus différentes, et depuis — là en été change sur les pommiers la question d'un combat de cet acarien nuisible par des application ultérieures ou par l'extermination d'herbes est discuté e.

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, Pannonychus ulmi Phosphorsäureester. Akarizide Ovizide. Tetranychus urticae , .

     

Sulfated glycofuranans as inhibitors of melanoma lung metastasis

Chemically synthesized (1 5)--d-glucofuranan, (1 5)--d-galactofuranan, (1 5)--d-xylofuranan, (1 5)--L-arabinofuranan, natural xylan, and curdlan were sulfated to investigate their inhibitory activities on B16-BL6 lung metastasis and anticoagulant activities. (1 5)--d-Glucofuranan sulfate, (1 5)--d-galactofuranan sulfate, xylan sulfate, and curdlan sulfate had binding abilities with B16-BL6 melanoma lysate. The inhibitory activities of sulfated polysaccharides on B16-BL6 lung metastasis selected by heparin binding assay were in the order (1 5)--d-galactofuranan sulfate > (1 5)---d-glucofuranan sulfate > xylan sulfate curdlan sulfate. Furthermore, (1 5)--d-galactofuranan sulfate, (1 5)--d-glucofuranan sulfate, and xylan sulfate had not only high inhibitory activity on B16-BL6 lung metastasis but also low anticoagulant activity. The correlation between chemical structure and biological activity is discussed.Part of this paper was presented at the 10th International Synposium on Wood and Pulping Chemistry, Yokohama, Japan, June 1999     

Generationszahl der RübenfliegePegomyia hyoscyami betae Curt.

Summary During the years 1959–1961 the number of generations was followed in Spinach Leaf Miner (Pegomyia hyoscyami betae Curt.) in central Bohemia at 310 m above sea level and in the year 1961 in southern Bohemia at 450 m. The larvae and the eggs were studied on the leaves at regular 10–14 days' intervals by controlling each plant and images by means of a sweeping method. There have been acertained two generations in the year 1959 and three generations in the year 1961 in central Bohemia and two generations in the year 1961 in southern Bohemia. The occurence of every generation of larvae on the suggar-beet was separate and the previous and the consecutive generation did not overlop.The origin of the erroneous date on 6–7 generations of this species (Rambousek, Neuwirth, 1931) has been also cleared up in this article. This statement has been taken over by Sorauer (1953) from the Review of Applied Entomology (1931) and has been lately mentioned by many authors. F. Neuwirth gave a personal information, that the statement on 6–7 generations occurence of Spinach Leaf Miner has been found on the basis of theoretical calculation (from the lenght of one generation in spring and not on the basis of the facts found in natural conditions).

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Résumé En 1959–1961 le nombre des générations de la mouche de la betterave a été observé dans la Bohème Centrale á l'altitude de 310 m audessus de la mer et en 1961 dans le Sud de la Bohème á l'altitude de 450 m. Les larves et les oeufs ont été observé sur les feuilles dans les intervalles de 10–14 jours regulierement effectués sur chaque plante et imagines en particulier par le filet fauchior. En 1959 deux générations et en 1960 et 1961 trios géné rations dans la Bohéme Centrale, ainsi que en 1961 deux générations dans le Sud de la Boheme ont été constates. La prence de chaque génération des larves sur la betterave aété separée et les générations consecutives ne malaient pas presque jamais avec les précedents.Dans cet travail l'auteur a clarifié comment une donnée fautive sur 6–7 générations de cette espéce est survenu (Rambousek et Neuwirth, 1931). Cette donnée orginante de Review of Applied Entomology [1931] a été reprise par Sorauer (1953) et elle a été ensuite récemment mentionée par d'autres auteurs. Selon une déclaration personelle de Mr. F. Neuwirth les donées des 6–7 générations de la mouche de la betterave en Tschécoslovaquie ent été acquis par une évaluation théoretique (se basant sur la durée de la génération du printemps et non sur les resultats des observations réelles dans les conditions naturelles.

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1959–61 . (310 . ) 1961 . (450 . ). 10–14 , . 1959 . 2 , 1960 . — 3, 1961 . — 2 . , . , 6–7 (Rambousek, Neuwirth 1931). . . 6–7 , , .

     

Richtungen der angewandten Entomologie in Bulgarien

Summary For protection of agricultural crops, archards, forests and stored products a system of institutes for vegetative protection have been gradually built in Bulgaria within the last fifteen years. Now a leading part in the study of pests and diseases of plants are taking the Academy of Rural Economy Sciences and the Institutes for Plant Protection, for Forest Protection, the Zoological Institute by the Bulgarian Academy of Science, the Higher Rural Economy Institute and the Higher Forest Institute. Specialists of all ranks are working at these institutes: academicians, member correspondents, professors, senior and junior scientific collaborators and a great number of experts and assistants. Parallel with the studies of specific composition of pestilent insects, their biology is being explored and experiments are being made with insecticides. An inquiry is also being undertaken for utilization biologic combat against noxious insects. In aid of scientific institutes a dense network of services for heading the research work and combat on the terrain has been organized.

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Résumé Pour la défense des cultures agricoles, des vergers, des forêts et des produits récoltés, un système d'instituts pour la défense végétale a été successivement dé veloppé en Bulgarie pendant les dernières quinze années. Actuellement l'Academie des sciences de l'economie rurale et les Instituts pour la défense végétale ont le rôle dirigeant dans les recherches de la nocivité et des maladies sur les plantes. Dans ces instituts travaillent des spécialistes de toutes les catégories scientifiques: des académiciens, des membres-correspondants, des professeurs, des travailleurs scientifiques supérieurs et plus jeunes, avec un grand nombre d'aides-spécialistes. Parallèllement à l'étude de composition specifique des insectes nuisibles on étudie sa biologie, de même on fait des expériences avec des insecticides. Aussi on cherche à utiliser la lutte biologique contre les insectes nuisibles. Pour faciliter les instituts scientifiques dans cette lutte et leur recherche sur le terrain, un immense service est organisé dans tous les plus grands emplacements peuplés du pays.

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. , 15 , , , . . - , , , . - , , - . : , , , . , . . , . - , . .

     

Analysis of current forest operations in the Okumikawa Forestry Area by location and topography

We analyzed current forest operations in Toei, in the Okumikawa Forestry Area, Japan, by examining actual achievement, location, and topography. We considered five basic forest operations conducted by the Forest Owners Association between 1991 and 2000 in a subsidized reforestation and silviculture project: planting, weeding, pruning, cleaning, and thinning. In addition, we considered the road network, including public, forest, and strip roads. The area in which forest operations have been conducted over the past 10 years amounted to less than two-thirds of the area targeted in the Toei Forest Improvement Plan. The mean access distance of the work sites was 164m, which was 52m less than the 10-year average for the whole forest (216m). Forest operations tended to ignore remote forest areas where the topography was steep, due to cost, the logging techniques required, and labor requirements. We determined that the limitations on forest operations in Toei were a 300m access distance, an elevation of 800masl, and a 90% slope. In accessing work sites, the utilization ratios of forest and strip roads were higher than their composition ratios, and public roads were used most. Newly constructed strip roads were used more than forest roads. Based on current forest operations, we calculated the road density and length required to be 7.1m/ha and 79.2km, respectively, with an estimated cost exceeding 720 million yen for new construction.     

Changes in the physical and chemical properties of six Japanese softwoods caused by lengthy smoke-heating treatment

The effects of prolonged smoke-heating treatments on wood quality were investigated. Six Japanese softwoods were smoke-heated for 100 and 200h at a temperature of 75° ± 5°C, which was recorded inside the log. After smoke heating, wood quality, including moisture content, amounts of chemical components, relative degree of crystallinity (RDC) of cellulose, and sapwood color were examined. Moisture content decreased as a result of smoke heating, especially in sapwood, leading to a uniform distribution of moisture content within a log. Almost no difference was found in the amounts of chemical components between the control woods and the woods that were smoke-heated for 100h. However, in the wood that was smoke-heated for 200h, the amounts of holocellulose decreased, suggesting that thermal deterioration and/or degradation of hemicelluloses had occurred. We assume that the increase in RDC was caused by smoke heating with the crystallization of cellulose and/or thermal degradation of hemicelluloses. Almost no differences were found in sapwood color between the control woods and the woods that were smoke-heated for 100h. In the wood that was smoke-heated for 200h, however, L*decreased, whereas a* and b* increased. As a result, E*ab, showing the total color change, increased, resulting in a deeper color. These results suggest that thermal degradation of hemicelluloses was caused by smoke heating for over 100h. Therefore, smoke heating of softwood logs using a commercial-scale kiln should not exceed 100h.     

Über die Beziehungen zwischen Boden und Forstschädlingen

Zusammenfassung Eine Anzahl von Forstinsekten verursacht stärkere Schäden vorwiegend in Beständen von bestimmtem Charakter. Veränderungen der Standortverhältnisse beeinflussen die Schädlinge auf verschiedene Weise und können über andere Glieder der Lebensgemeinschaft wirksam werden. Es wird eine Übersicht über die denkbaren Zusammenhänge zwischen dem Zustand der Wirtspflanze und dem Auftreten einer Insektenart gegeben. Der für den Befall eines Sehädlings optimale Zustand der Wirtspflanze ist für standort-oder bestandesbedingtes Schädlingsauftreten von besonderer Bedeutung. Als Beispiel wirdEvetria (Rhyacionia) buoliana Den. & Schiff. angeführt.

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Summary A number of insect pests frequently cause severe damages in forest stands of certain types. Changes in quality of the site influence forest insects in different ways and may act through other members of the community. A review is given of the possible relations between the condition of the host plant and the occurrence of a phytophagous insect. The site- or stand-dependent occurrence of an insect species, e. g.Evetria (Rhyacionia) buoliana Den. & Schiff., is connected with the optimum condition of the host tree with respect to attack.

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Résumé Nombre d'insectes forestiers causent de grands dommages surtout dans les peuplements d'un certain type. Les changements de qualités des habitats influencent les insectes nuisibles de diverses manières et peuvent agir sur eux par l'ntermediaire d'autres membres de la biocénose. Un aperçu est donné des relations possibles entre la condition de l'hôte et l'apparition d'une espè d'insectes. La condition optimale de l'hê pour l'attaque d'un insecte nuisible est d'une importance particulière pour l'apparition d'insectes conditionnée par l'habitat et ie peuplement, par exemple chezEvetria (Rhyacionia) buoliana Den. & Schiff.

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. . . , , , . ,Evetria (Rhyacionia) resinella Den. & Schiff.

     

Vibrational properties of wood plastic plywood

Wood plastic plywood (WPPW), composed of veneer and styrofoam, was manufactured without special adhesives such as urea–formaldehyde or phenol–formaldehyde resins, and its vibrational properties were investigated. WPPW can be produced at 1MPa and 160°C for 9min (three-ply) and 12min (five-ply). The dynamic Youngs modulus reached its highest value when the styrofoam thickness was 30mm. The sound velocity and dynamic Youngs modulus had minimum values at a grain angle of 45°. The results for dynamic Youngs moduli measured by a longitudinal vibration method and an in-plane flexural vibration method were almost the same. Dynamic shear moduli were measured by an in-plane surface wave propagation test and an in-plane flexural vibration method. From the experimental results, the dynamic shear moduli at 0° and 90° by the two methods were relatively close, although the surface wave propagation test results were higher than those from the flexural vibration method. Dynamic shear moduli at a grain angle of 45° measured by the in-plane surface wave propagation test and calculated from theory were relatively close. The surface wave propagation test results were smaller than the results calculated from theory. The shear stress distribution factors were about 1.000–1.189 for WPPW.     

Modelling the long-term strength of timber columns

Summary This paper studies the influence of the used creep function, and the duration of the experimental sustained loading from which the creep function was derived, in modelling the long-term buckling strength of timber columns. The sensitivity of this buckling strength to creep and initial deflection is numerically studied using an energy approach that takes into account the initial deflection. Various creep functions — power laws as well as exponential laws — derived from bending experiments of different durations are used for the numerical simulation. The crucial need for experimental results issued from very long load period experiments is identified. Such experiments may lead to a more credible creep analysis of timber structures.Symbols i radius of giration - s stress level - E_L effective MOE - E₀ instantaneous MOE - I inertia moment - K,K geometrical matrices - L length of beam or column - L_f effective length - N_cr axial force, buckling load - U elastic strain energy - W external forces work - t time variable - u moisture content (m.c.) - v total deflection - v_c, v_e, v₀ creep, instantaneous elastic and initial deflections respectively Greek Letters (t) time function - , _e, ₀ total, instantaneous and initial strains respectively - twist rotation - (t) creep coefficient or fractional creep or relative creep - (x) shape function - load factor - longitudinal shortening - total potential energy - creep factor - relaxation time     

Biological performance of wood-based composites treated with a formulation of 3-iodo-2-propynyl butylcarbamate and silafluofen using supercritical carbon dioxide

Wood-based composites (medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board) treated with a mixture formulation of 3-iodo-2-propynyl butylcarbamate (IPBC) and silafluofen using supercritical carbon dioxide as a carrier solvent were evaluated for their resistance to biological attack in a laboratory study. The formulation was pre-pared by mixing 10g of IPBC and 1g of silafluofen in ethanol solution (20ml). Treatments were conducted at 35°C/7.85MPa, 35°C/9.81MPa, and 55°C/11.77MPa with the direct introduction of 20ml of the formulation into the treatment vessel with a capacity of ca. 2000ml at a rate of 2ml/min. Laboratory tests indicated that the treatment conditions used significantly enhanced the resistance of the treated wood-based composites against fungal and termite attacks. Because no significant difference in efficacy against both biodegrading agents was noticed regardless of the treatment conditions, the treatment at 35°C/7.85MPa was thought to be the most economical in terms of energy consumption and performance of treated materials. However, the amount of biocides in a formulation must be carefully selected in accordance with the required treatment condition to ensure satisfactory performance of the treated wood-based composites against any biological agent.     

Zur Technik der Untersuchung von Erdbeerpflanzen und Chrysanthemenblättern auf Blattälchen (Aphelenchoides fragariae undA. ritzemabosi)

Zusammenfassung Die Befallsstärke von Erdbeerpflanzen durch Blattälchen wird allgemein in Älchen je 20 g Herzen ausgedrückt. Man versteht unter dem Herz einer Erdbeerpflanze die Knospe, die jungen Blütenanlagen und die unentfalteten Blätter. Es besteht aber ein gewisser Ermessensspielraum in der Zuordnung zu gefaltet bis zu voll entfaltet. Meist ist die Knospe am dichtesten befallen. Der Durchschnittsbefall sinkt deshalb um so tiefer, je mehr nicht zur Knospe gehörende Pflanzenteile mituntersucht werden. Es handelt sich um die Frischgewichte der Herzen. Diese unterliegen Schwankungen je nach Jahreszeit, Erdbeersorte und Witterung. Ferner sind die Herzen stark befallener Pflanzen leichter als die gesunder Pflanzen. Im Durchschnitt wiegen im Frühjahr 30 Herzen 20 g. Es wird vorgeschlagen, die veränderliche Bezugsgröße 20 g Herzen durch das konstante Maß 30 Pflanzen oder 30 Rosetten zu ersetzen.

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Summary On the isolation of bud and leaf nematodes (Aphelenchoides fragariae andA. ritzemabosi) from strawberry and chrysanthemum. Part II.The degree of infestation to strawberry plants by the leaf and bud nematodes is usualy expressed in nematodes per 20 g hearts. The heart of a strawberry plant includes the bud, the young inflorescences and the young closed leaves. A certain degree of judgement is requirred to distinguish between a closed leaf and an opened one. As the nematodes are usualy most concentrated in the bud, the degree of infestation is brought down by the inclusion of parts of the plant that do not directly belong to the bud.The weight of the hearts is also natably affected by weather conditions, season and plant variety. Furthermore heavily infested hearts are lighter than healthy ones. In spring, 30 hearts weigh approximately 20 g. It is suggested that the unstable measure of 20g hearts be substituted by the more reliable amount 30 plants or 30 rosettes.