Necrophylactic periderm formation in the roots of western larch and Douglas‐fir trees infected with Armillaria ostoyae. II. The response to the pathogen

Periderm formation was studied in bark samples collected from the roots of western larch (Larix occidentalis) and Douglas‐fir (Pseudotsuga menziesii) trees infected with Armillaria ostoyae. Necrophylactic periderms were formed in advance of infection and successfully restricted continued fungal spread in 68 and 45% of the samples collected from 10‐ and 27‐year‐old western larch, respectively. However, all periderms formed in 11‐ and 25‐year‐old Douglas‐fir had been breached by the advancing fungus. In both species, necrophylactic periderms were commonly breached at the junction of the periderm with the vascular cambium. In western larch, stone phellem often comprised the external phellem layer of necrophylactic periderms with multiple bands of phellem. In 27‐year‐old western larch, infection was often confined to discrete lesions bounded by multiple periderms with multiple bands of phellem. In both tree species, phellem production was greater in response to infection than in response to abiotic wounding.     

Influence of saponin plants on the volatile fraction of thyme in herbal teas

Combinations of thyme, cowslip and liquorice roots are often used in the treatment of upper respiratory tract infections. Therefore the volatile fraction of herbal teas prepared from thyme (Thymus vulgaris) and the effect of combining with cowslip (Primula veris/P. elatior) and liquorice roots (Glycyrrhiza glabra) on the volatiles were analyzed. Volatile compounds were isolated by hydrodistillation and solid phase extraction and analyzed by GC-MS. Thymol was also quantified by HPLC. The total amount of volatiles as well the thymol content was decreased with increasing proportions of cowslip or liquorice in the infusion extracts whereas the proportion of monoterpene hydrocarbons increased.     

Welche Nutzorganismen sind in Europa für den blologischen Pflanzen- und Gesundheitsschutz verfügbar?

Zusammenfassung Angesichts fehlender Information über die kommerzielle Verfügbarkeit in Europa von Biopräparaten (auf der Basis von Mikroorganismen einschl. der Viren) und von nützlichen Metazoen für biologische Maßnahmen zur Unterdrückung von Schadorganismen wurde an die amtlichen Stellen, ausnahmsweise an Einzelexperten in folgenden Ländern eine Umfrage gerichtet: Frankreich, Großbritannien, Italien, Österreich, Rumänien, Jugoslawien, Schweden, die Schweiz, die Niederlande, Finnland und Bundesrepublik Deutschland. Die Ergebnisse werden in 2 Teilen als ein Momentbild des Zustandes Anfang 1984 vorgelegt. Im Begleittext wird für die Annahme einer Europäischen Zulassungsordnung für Biopräparate plädiert (die als Entwurf bereits vorliegt), um Zeit und Geld zu sparen. Zwischen den einzelnen Ländern bestehen sehr große Unterschiede bezüglich der Verfügbarkeit biotischer Agentien für biologische Verfahren. Einige vielversprechende neue Entwicklungen werden kurz in der Hoffnung vorgestellt, daß sie stimulierend wirken. Allen Kollegen, die bei der Umfrage geholfen haben, sei besonders gedankt.

---

Which beneficial organisms are available in Europe for biological plant and health protection

In view of the lack of information concerning the commercial availability in Europe of biopreparations (based on microorganisms including viruses) as well as of beneficial metazoa for biological control of pest organisms, an inquiry was started for the following countries: France, Great Britain, Italy, Austria, Rumania, Yugoslavia, Sweden, Switzerland, the Netherlands, Finland and Germany Fed. Rep. Results are presented as a momentary picture of the situation in early 1984. A plead is made for the acceptance of an European protocol for registration of biopreparations (which has already been drafted) in order to save money and time. There are great differences between countries in the availability of biotic agents for biological control. Some very promising new developments are briefly reviewed and considered to act in a stimulating way. Thanks are due to those colleagues who helped to obtain the information here presented.

---

---

Mit 2 Tabellen     

Hybridization between Quercus robur and Q. petraea in a mixed oak stand in Denmark

? Hybridization and mating pattern between Quercus robur and Q. petraea was studied in a 5.8 ha mixed forest stand in Jutland, Denmark which comprises in total 135 Quercus robur and 230 Q. petraea trees. Classification of the oak trees into species was performed using canonical discriminant analysis of a range of leaf morphological traits. Adult trees (365) and offspring (582) were genotyped with eight microsatellite markers. Seedlings were sampled in 2003 and acorns were collected in 2004.

? Mating patterns of Q. robur and Q. petraea are expected to be different in the northern range of the distribution area and a larger hybridization rate is expected. It is further expected, that pollination from outside sources will be relatively less in small fragmented forest management systems compared to large scale oak forest. The conclusions should be verified through repeated year to year analysis of the mating pattern.

? Phenological studies revealed that there was no difference in flowering time between species. Data for the adult trees revealed no significant departures from Hardy-Weinberg proportions and there was weak, but significant spatial genetic structure, which supports the idea that the stand is of natural origin. Spatial genetic structure in the first distance class is stronger for Q. petraea. The genetic composition of the offspring was remarkably consistent from year to year. Paternity analysis revealed that, on average, 85% pollination came from fathers within the stand. The direction of the pollen flow varied from year to year. Inter-specific hybridization was high and ranged from 15–17% and from 48–55% for Q. petraea and Q. robur mothers respectively. Paternity analysis revealed that the population was basically outcrossing and only 3.7% of the analysed progeny were the product of selfing. Over the two years of study, approximately 200 trees contributed to the paternity of the next generations.

? The study confirms earlier studies with a greater tendency for Q. robur mothers to produce hybrid seeds than Q. petraea mothers. The rate of hybridization is higher in this Danish stand than in comparable studies elsewhere in Europe. Gene flow from outside sources are relatively low.

     

Crototropone, a new tropone derivative from Croton zehntneri

Crototropone (3-hydroxy-5,6-dimethoxy-2-methylcyclohepta-2,4,6-trien-1-one) was isolated from roots of Croton zehntneri. The structure was established by spectroscopic methods.     

In search of a variance estimator for systematic sampling

Seven variance estimators to be used under systematic sampling are evaluated in a simulation study with 270 artificial spatial populations with different levels and structure of autocorrelation. In settings without an auxiliary variable a proposed new spatial resampling estimator RHO is recommended. In setting with an auxiliary variable, an estimator based on post-stratification (PST), and one with a correction for spatial autocorrelation (DOR), generated estimates with less bias than the SRS estimator in the majority of studied settings. Only in populations with either a near zero autocorrelation at the interval of sampling, or a very strong correlation between the target and the auxiliary variable did the otherwise conservative SRS estimator perform as well as the alternatives.     

Plywood frame corner joints with glued-in hardwood dowels

This paper presents research on plywood frame corners jointed to glulam beams and columns by means of glued-in hardwood dowels. The frame corner was made of a solid block of ordinary plywood of the same width as the glulam beams and with plies parallel to the plane of the frame to avoid splitting due to stress perpendicular to the grain. Hardwood dowels with a diameter of 12mm and a maximum glued-in length of 120mm were glued into drilled holes in the plywood corner and glulam beam ends parallel to the grain direction of the beams to form a momentresisting joint. Static bending tests were conducted of frame corners with 100 X 200mm² and 120 X 420mm² beam cross sections. Bending capacities of the joints corresponding to a modulus of rupture of the jointed glulam beams of about 30MPa were obtained for both closing and opening moments for the small cross sections, and about 22MPa was obtained for the large cross sections. Simple design models for calculation of joint strength and rotational stiffness are also presented.     

A new composite k-tree estimator of stem density

This study presents a generally applicable and robust k-tree composite estimator of density. We propose to estimate stem density by a weighted average $ \left( {\hat{\lambda }_{\text{aic}} } \right) $ of 16 individual density estimators. The weights given to individual estimators are inversely proportional to the relative fit (Akaike’s corrected information criterion) of each estimator to the assumed distribution of observed k-tree distances. The performance of the proposed estimator is evaluated in simulated simple random sampling with k?=?3 and 6 in 58 forest stands (54 actual and 4 simulated) and 600 replications. Sample sizes were 15 and 30 locations per stand. Eleven estimators were novel, including three designed for regular spatial patterns. Absolute stand-level bias with k?=?6 varied from 0.1 to 8.1% (mean 1.8%), and a bias larger than 6% was limited to 3 stands with either pronounced density gradients or a strong clustering of stem locations. Root mean squared errors were approximately 16% (k?=?6 and n?=?15) versus 12% for sampling with comparable fixed-area plots. Coverage of computed 95% confidence intervals ranged from 0.72 to 0.99 (median?=?0.98 with n?=?15 and 0.95 with n?=?30), with 98% of all intervals achieving a coverage of 0.85 or better. In seven stands used in an assessment of a novel spatial point pattern reconstruction k-tree density estimator (RDE) by Nothdurft et al. (Can J For Res 40:953–967, 2010), the average absolute bias of $ \hat{\lambda }_{\text{aic}} $ with k?=?6 was 1.5 versus 0.7% for $ \hat{\lambda }_{\text{RDE}} $ .