Überlebensdauer vorratsschädlicher Insekten in Getreidekühllägern

Under the temperature conditions of cold-storage of grain, i.e. 6–9°C, the Granary Weevil (Sitophilus granarius) could survive for more than 2 years. The Khapra Beetle (Trogoderma granarium) survived for more than 11/2 year and the longevity of the Saw Toothed Grain Beetle (Oryzaephilus surinamensis) and the Turkish Flat Beetle (Cryptolestes turcicus) exceeded 1 year. The Confused Flour Beetle (Tribolium confusum) proofed to be much less cold resistant and did not survive half a year under the conditions mentioned above. The unexpected short longevity of max. 1 year of the Flour Mite (Acarus siro) may have been caused by desiccation of the grain during cold storage. From practical aspects of stored products protection also long-term cold-storage of grain cannot be taken as a guarantee for complete desinfestation.     

Über die Wirksamkeit verschiedener Antikoagulantien gegen forstschädliche Wühlmäuse

The susceptibility of rodents in forest cultivations against some anticoagulants was tested in a pilot study. The species used were the Common Vole (Microtus agrestis), the Redbacked Vole (Clethrionomys glareolus) and the Yellownecked Field Mouse (Apodemus flavicollis). The following anticoagulants were administered orally: Coumatetralyl (Racumin^®), Warfarin + Pindon (Actosin P^®), Chlorphacinon + Sulfaquinoxalin (Lepit^®), Bromadiolon, Brodifacoum and Flocoumaphen. Prothrombin times and mortality were observed. Promising preliminary results were obtained with Flocoumaphen which was effective against the harmful voles but not against the useful mice in the plantations.     

On the mechanical behaviour of water soaked wood at various states of stress

Summary The paper is concerned with an experimental investigation of the swelling strains and mechanical strains of water soaked wood under one- and two-dimensional stress states at changing moisture content. The aim of this paper is to develop an experimental basis for setting up the physical relations between strains, stresses and moisture content in wood.     

Combustion gas toxicity,hygroscopicity, and adhesive strength of plywood treated with flame retardants

Summary The results of tests of combustion toxicity, hygroscopicity, and adhesive strength for fire retardant-treated plywood are described. The plywood was prepared from veneers treated with diammonium phosphate and ammonium bromide, and from glue mixed with poly (ammonium phosphate). Furthermore, the plywood boards were coated with boric acid. High ammonium phosphate and low or 0 ammonium bromide contents with the boric acid-coatings gave the greatest improvement in the combustion toxicity. Influence of almost all the treatments on the hygroscopicity was not significant. In all treatments the dry adhesive strength and the cyclic boil adhesive strength were slightly and considerably reduced, respectively.     

Collapse phenomena in eucalypts

Summary Trees belonging to the genus Eucalyptus are specifically prone to developing damage due to collapse soon after felling. Observations on 150 trees of five Eucalyptus species from two growth sites, indicate that collapse occurs in the wake of the receding liquid water supposedly moving from the heartwood fibres into the rays, and from there to the vessels of sapwood and to the pith (heart shakes), respectively from where it evaporates. Collapse was observed over the entire cross section of stems. Anatomical evidences suggest a collapse modifying process across the stem from the pith to the cambium. Generally, the stresses generated cause tangential flattening of fibres and open radial/longitudinal splits in the tissue. Fibres seem to collapse in radial strings and also in small lumps scattered over the xylem. Based on their effect, the level of collapse stresses must be greater than the cross-grain tension strength but smaller than the longitudinal compression strength of the wet wood. The results suggest that the prediction of collapse susceptibility of standing trees is possible.This investigation was sponsored by the South African Mining Timber Manufacturers Association, the University of Stellenbosch and the Institute for Commercial Forestry Research, Pietermaritzburg whose support is gratefully acknowledged here     

Zur Problematik des Stehendbefalls durch den Großen Waldgärtner,Blastophagus piniperda L.

Zusammenfassung Um Grundlagen für die Behandlung von Kiefernbeständen mit Stehendbefall durch den Großen Waldgärtner zu erarbeiten, wurden im Juli 1984 im Kirchenstiftswald Lindenhardt bei Bayreuth 3 Beobachtungsflächen angelegt. In diesen Flächen wiesen 53% der untersuchten Kiefern Einbohrungen auf. An 19 befallenen Bäumen wurde die vertikale Verteilung der Einbohrungen am Stamm erfaßt. Bestandsbildende Kiefern wurden häufiger als unterdrückte und zurückgebliebene Kiefern befallen; Bäume mit gebrochenem Wipfel wurden nicht bevorzugt attackiert. Von den 105 Kiefern der 3 Flächen wurde bis zum Herbst 1985 kein Baum durch den Großen Waldgärtner zum Absterben gebracht; der durchschnittliche Benadelungszustand der Kiefern veränderte sich über den Beobachtungszeitraum nicht. Anhand der erhobenen Daten wird die waldbauliche Behandlung von Kiefernbeständen bei Waldgärtner-Stehendbefall diskutiert.

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Problems of infesting standing trees byBlastophagus piniperda L.

Since July 1984 three plots of pine forest attacked byBlastophagus piniperda were studied near Bayreuth in Northern Bavaria. 53% of the examined trees were infested; in 19 of the trees the verticale distribution of the bore-holes was studied. The stand forming pines were more often infested than the suppressed ones (and the laggards), and trees with broken crowns were not preferred to others by the bark beetles. Up to autumn 1985 none of the 105 trees in the three plots were killed byB. piniperda. The average state of foliation of the pines did not change during the observation period. Based on the results of this study silvicultural measures in the management of pine forests attacked byB. piniperda are discussed.

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Mit einer Abbildung und 4 Tabellen     

Berichte

Ohne Zusammenfassung     

Effects of chemical treatments on ultra-high-yield pulping 1. Fiber separation

Summary Specially designed wood blocks from Norway spruce were used to study the nature of the fracture surfaces developed in shear using a tensile tester. In the case of the control (water-soaked blocks), the fracture in the latewood takes place mainly in the S₁ layer while in the earlywood the fracture occurs across the double cell wall. After dilute alkali treatment, some earlywood cells also fracture in the S₁ layer. For sulfite-treated samples, on the other hand, both earlywood and latewood fracture in the middle lamella.Financial support from the Empire State Paper Research Associates (ESPRA) is greatly appreciated     

Über die Eignung einiger Winterkulturen und Winterunkräuter als Wirtspflanzen von Wurzelnematoden in Ägypten

Host-reaction of three winter field crops in comparison with four winter weeds toMeloidogyne javanica was evaluated in a pot-experiment. The results indicated that the weedVicia calcarata was the highly infected one. On contrary, no infection took place at all in the roots of the weedsCoronopus sequamatus andAnagallis arvensis. In the roots of winter field crops,Vicia faba cultivar (Giza, 3) was highly infected withM. javanica, and followed byTrifolium alexandrinum cultivar (Miskawy) in a decreasing order. No infection took place in the roots ofTriticum vulgare cultivar (Giza, 157). Finally, it could be concluded thatVicia calcarata has a great role as a source of infestation ofM. javanica to the main winter field crops, i. e.,Vicia faba (Giza, 3) andTrifolium alexandrinum (Miskawy), where, it is intercropping in. So, controlling weeds is an important factor in reducing nematode population.