The occurrence of aphid wax in peat

Small white aggregates frequently observed in peat have been studied using scanning electron microscopy and infrared absorption spectrometry. It has been shown that they are fibrous, consisting of paraffin wax and associated carbohydrate and secondary amide, and are secreted by the aphid Colopha compressa, which colonizes the roots of Eriophorum spp. growing on peat. This is the first report of the occurrence of this aphid species in Scotland.     

LIME AND PHOSPHATE TREATMENTS FOR RECLAMATION OF HEATHER MOORLAND

The use of lime and phosphates in reclaiming heather moorland was investigated in two experiments.
Large initial dressings of hme resulted in a rapid rise in pH. An initial dressing of 9 tons CaCO₃/ac resulted in a more rapid rise to pH 6 than did 6 tons/ac and the soil was maintained above pH 6 for a longer period. Three annual dressings of 3 tons/ac gave a slower rise in pH and a longer period above pH 6. Split treatments, half before and half after the first ploughing, gave no long–term advantage where a programme of pioneer cropping was being followed.
Basic slag and North African phosphate were as effective as superphosphate for root crops at low pH values. Basic slag was as effective as superphosphate for grassland establishment and gave a greater rise in soil phosphate. North African phosphate was virtually worthless as a source of phosphate for establishing grasses and clovers, and gave a negligible rise in soil phosphate.
Given adequate supphes of lime and phosphate, frequent small apphcations of N over the first 2 or 3 years are vital to the success of a reclamation programme under the conditions described.     

USE OF CONTRAST‐ENHANCED COMPUTED TOMOGRAPHY TO STUDY THE CRANIAL MIGRATION OF A LUMBOSACRAL INJECTATE IN CADAVER DOGS

Volumes used in lumbosacral epidural injections for anesthesia have remained unchanged since the 1960s. The goals of this cross‐sectional observational study were to characterize the three‐dimensional spread of a lumbosacral epidural injection, as well as confirm that the commonly used volume of 0.2 ml/kg injected into the lumbosacral epidural space reaches the thoracolumbar (TL) junction in the majority (≥80%) of dogs. Ten clinically normal, adult, nonpregnant, mixed‐breed dogs were obtained within five minutes of euthanasia and 0.2 ml/kg of radiopaque contrast medium was injected into the lumbosacral epidural space. A computed tomography scan of the TL spine was performed immediately following the injection. Migration of contrast reached the TL junction in 8 of 10 (80%) dogs. Contrast was well visualized in all epidural planes with contrast travelling predominantly in the dorsal epidural space in 7 of 10 (70%) dogs. There was no significant difference in the weight of dogs where the epidural injectate reached the TL junction and those where it did not (P = 0.16), or in the weight of dogs where the cranial‐most point of the contrast column was in the dorsal versus the ventral epidural space (P = 0.32). This preliminary study supports the use of computed tomography to characterize injectate distribution in the canine thoracolumbar epidural space and provides evidence that a 0.2‐ml/kg volume is likely to reache the TL junction in most dogs. Further studies are needed in live dogs to determine if variables affecting human epidural injectate doses have similar effects in the dog.     

Effect of thinning and fertilizer on the cellulose crystallite width of Eucalyptus globulus

An analysis of cellulose crystallite width, microfibril angle and wood density after the time of thinning (at 8 years) in straight vertical trees was undertaken in a 13-year-old E. globulus trial designed to assess the effect of thinning on tension wood formation. The most important effect was on cellulose crystallite width, which increased with thinning intensity and this was mitigated where fertilizer was applied at the time of thinning. Given the relationship between high crystallite width and tension wood occurrence the results demonstrate that heavy thinning of E. globulus at this age can contribute to tension wood formation. However, tension wood production may be significantly reduced where fertilizer is applied. This is possibly because increased diameter growth as a response to fertilizer application stabilises the stems and this is the mechanism by which trees cope with internal stresses that are generated from wind in destabilsed stands following thinning. In contrast, trees that respond poorly to thinning produce tension wood.     

Qualitative resistance to powdery mildew in hybrid sweet peas

Lathyrus odoratus L. × Lathyrus belinensis L. hybrids were produced using L. belinensis as the pollen parent, with fertile seed produced by the L. odoratus parent. The F1 hybrid plants were completely self-sterile, but produced viable seeds when backcrossed to L. odoratus. The plants produced by backcrossing resembled L. odoratus, the flower colour being purple/magenta, and were self-fertile. Both hybrid plants and those produced by back crossing to L. odoratus were resistant to Erysiphe pisi DC that causes powdery mildew in sweet peas. Continued backcrossing resulted in hybrid plants, that closely resembled the L. odoratus parent, but segregated for complete resistance/susceptibility to E. pisi,with a ratio of 2.46:1 resistant to sensitive plants. This suggests the presence of a single dominant gene that confers resistance. When resistant and sensitive plants were inoculated with E. pisi and their leaf surfaces examined,using a Scanning Electron Microscope, it was found that although spores germinated on the leaves of both resistant and sensitive plants, spores present on resistant plants collapsed shortly after germination. Possible reasons for this are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.