Electrostatic method to separate roots from soil

Complete removal of roots from soil samples is a prerequisite for most of the chemical and biological analyses. A simple electrostatic method of separating roots from sieved, largely mineral soil substrates was optimized and examined by the addition of ¹⁴C labeled fine roots to sandy, silt loamy and clay loamy samples. Depending on soil texture, between 40% and 50% of fine roots can be removed from 100 g of sieved soil in less than 10 minutes. The root‐free soil substrate and the extracted roots can be used for analyzes or experiments immediately after the separation. The proportion of the mineral particles remaining in the root fraction depends on duration of separation, distance between the charged plate and the sample, and soil texture. The proportion of separated mineral particles is about 90%—95% (w/w) in sandy and 70%—85% in silt loamy and clay loamy substrates. The electrostatic method of root separation may take place before the analysis of C_t and N_t contents, and is suitable for soil samples preparation for incubation experiments.     

Review: Resistance as a concomitant of modern crop protection

This paper reviews the impact of resistance to fungicides and insecticides/acaricides on the way crop protection is practised. It is now clear that resistance can develop to virtually any crop-protection product, in any pest, fungal pathogen or even weed. As a limiting factor in crop protection, it is a fact of life. A positive side-effect is the precision with which products are used today, with increasing implementation of Integrated Pest Management (IPM) programmes. This is a vital step towards sustainability. This paper describes: past experiences; current status of resistance; how resistance management influences current crop protection practices; regulatory aspects; and the outlook for the future. It concludes that EU regulations on resistance management must be simple and workable. Chemicals will continue to have a central role in optimising yields from the world's crops, as new tools, including biotechnology, become available for crop protection and resistance management. The crop-protection industry's innovations and product stewardship programmes will contribute to sustainable agriculture. This will provide continued benefits to users, the environment and society. ©1997 SCI     

Disinfection of almaco jack (Seriola rivoliana Valenciennes) eggs: Evaluation of three chemicals

Almaco jack (Seriola rivoliana Valenciennes) is an excellent candidate for aquaculture due to its fast growth rate and high market value. While S. rivoliana have adapted well to captivity, survival at early life stages can be improved to increase profitability during production. A wide range of variables cause larval mortalities but high bacterial loads in rearing tanks are often correlated with these losses. The aim of this study was to investigate the effect of egg disinfection on bacterial load and hatch rate of S. rivoliana. Disinfectants tested included formalin (F100 and F200; 100 and 200 mg/L, respectively, for 60 min), hydrogen peroxide (HPO; 300 mg/L for 10 min) and peracetic acid/hydrogen peroxide (PAA/HPO; 15.7 mg/L/39.6 mg/L for 1 min). Concentrations and contact times were determined based on current use in marine aquaculture and preliminary trials. Eggs treated with HPO and F100 had significantly higher hatch rates than the untreated control group. All treatments significantly decreased total Vibrio counts compared to untreated eggs; however, total bacterial counts were only decreased following treatments with PAA/HPO and F200. To prevent egg mortality due to bacterial overgrowth, consideration should be given to the use of surface disinfection using HPO or F100. Future studies should investigate the use of peracetic‐based products at lower doses.     

Conservation implications of isotopic variation in nails and blood with wetland quality in three species of Australian freshwater turtle

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Gastrointestinal Protozoal Diseases in Reptiles

This article outlines the principal gastrointestinal protozoal diseases that have been recorded as affecting reptiles. It covers 9 genera of flagellates/amoebae, 1 ciliate genus, and 5 genera of coccidia, describing their pertinent anatomy and what is known about their epidemiology, including clinical presenting signs and intestinal pathological changes. The agents are initially discussed individually and, to avoid repetition, common information about diagnostics, treatment, and control is then presented.     

State-of-the-art review of goat TSE in the European Union, with special emphasis on PRNP genetics and epidemiology

Scrapie is a fatal, neurodegenerative disease of sheep and goats. It is also the earliest known member in the family of diseases classified as transmissible spongiform encephalopathies (TSE) or prion diseases, which includes Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE), and chronic wasting disease in cervids. The recent revelation of naturally occurring BSE in a goat has brought the issue of TSE in goats to the attention of the public. In contrast to scrapie, BSE presents a proven risk to humans. The risk of goat BSE, however, is difficult to evaluate, as our knowledge of TSE in goats is limited. Natural caprine scrapie has been discovered throughout Europe, with reported cases generally being greatest in countries with the highest goat populations. As with sheep scrapie, susceptibility and incubation period duration of goat scrapie are most likely controlled by the prion protein (PrP) gene (PRNP). Like the PRNP of sheep, the caprine PRNP shows significantly greater variability than that of cattle and humans. Although PRNP variability in goats differs from that observed in sheep, the two species share several identical alleles. Moreover, while the ARR allele associated with enhancing resistance in sheep is not present in the goat PRNP, there is evidence for the existence of other PrP variants related to resistance. This review presents the current knowledge of the epidemiology of caprine scrapie within the major European goat populations, and compiles the current data on genetic variability of PRNP.     

Efficacy of a 5-day extended therapy program during lactation with cephapirin sodium in dairy cows chronically infected with Staphylococcus aureus

This study determined the efficacy of a 5-day extended therapy with cephapirin sodium in dairy cows chronically infected with Staphylococcus aureus. Chronically infected cows selected from 14 dairy herds in the St-Hyacinthe region, Québec were randomly allocated to a group of 31 cows treated for 5 consecutive days with 200 mg of cephapirin per quarter BID or a group of 30 untreated control cows. Bacteriological cure was determined by 3 negative bacterial cultures at 10, 24, and 31 days after treatment. The cow cure rates were 25.8% (8/31) in the treated cows and 3.3% (1/30) in the control group (P = 0.013). The quarter cure rates at first sampling post-treatment were 77.6% (38/49) and 18% (9/50) in the treated and the control groups, respectively (P < 0.0001). A 5-day extended therapy with cephapirin is effective in treating cows chronically infected with S. aureus.     

Post-fire tree stress and growth following smoldering duff fires

Understanding the proximate causes of post-fire conifer mortality due to smoldering duff fires is essential to the restoration and management of coniferous forests throughout North America. To better understand duff fire-caused mortality, we investigated tree stress and radial growth following experimental fires in a long-unburned forest on deep sands in northern Florida, USA. We burned basal fuels surrounding 80 mature Pinus palustris Mill. in a randomized experiment comparing the effects of basal burning treatments on stem vascular meristems; surficial roots; root and stem combinations; and a non-smoldering control. We examined the effects of duration of lethal temperatures (>60 °C) on subsequent pine radial growth and root non-structural carbohydrates (starch and sugar). Duff and mineral soil temperatures in the experimental fires consistently exceeded 60 °C for over an hour following ignition, with lethal temperatures of shorter duration recorded 20 cm below the mineral soil surface. Duff heating was best explained by day-of-burn Oe horizon moisture (P = 0.01), although little variation was explained (R² = 0.24). Post-fire changes in latewood radial increment in the year following fires was related to duration of temperatures >60 °C 10 cm deep in the mineral soil (P = 0.07), but explained little variability in post-fire growth (R² = 0.17). In contrast, changes in non-structural carbohydrate content in coarse roots (2–5 mm diameter) 120 days following burning were more strongly correlated with the duration of lethal heating 5 cm below the mineral soil surface (P = 0.02; R² = 0.53). Results from this study implicate the role of mineral soil heating in the post-fire decline of mature longleaf pine following restoration fires in sandy soils.