Recent Developments in Pesticide Application by the United States Animal and Plant Health Inspection Service1

Aerial application of pesticides is generally the method used by the United States Department of Agriculture (USDA) in the control of pests of rangeland, cultivated crops, and forested areas. With increased restrictions placed on pesticides, then- continued use requires improved application technology to meet acceptable levels of risk at reasonable cost The Animal and Plant Health Inspection Service of USDA is developing an aerial spray drift model for use by their field personnel to minimize drift from aerial application of pesticides to environmentally sensitive areas. Input information utilizing a low cost, field-deployable microcomputer includes aircraft type, application technique and hardware, pesticide formulation, meteorological conditions, and type (roughness) and extent of the site. Expected output computations will be: 1) distribution pattern of downwind deposition, including evaporation corrections and matching to empirical field measurement; 2) optimal aircraft swath spacing; and 3) buffer distance between the target area and the environmentally sensitive areas.     

Evaluation of Methods for Control of Ammonia Volatilization from Surface-Applied Nitrogen Fertilizers to Sugarcane Trash in North Queensland

Micrometeorological and microplot experiments were conducted in the field of freshly harvested green cane in Queensland,Australia.Results showed that high ammonia loss of fertilizer N could occur under relatively dry conditions when urea or commercial product of mixture of urea and muriate of potash were applied to the surface of sugarcane trash.The moisture content in the trash and the pH of fertilizer were two important factors controlling the processes of urea hydrolysis and ammonia volatilization.Most of the N in the soil was transformed to the nitratel-nitrite from after 70 days of fertilizer application.No significant leaching was found.Urea-free N fertilizers had higher N recoveries compared to urea-containing fertilizers.     

Protection of sheep by vaccination against experimental challenge with Leptospira borgpetersenii serovar Hardjo and L. interrogans serovar Pomona

AIMS: To evaluate a multivalent leptospiral and clostridial vaccine for prevention of renal colonisation and urinary shedding in sheep, following experimental challenge with New Zealand strains of Leptospira borgpetersenii serovar Hardjo type Hardjobovis and L. interrogans serovar Pomona.

METHODS: Two separate but similarly designed studies were conducted. In both studies, Romney-cross lambs, aged 9–11 weeks, were randomly allocated to a vaccinated group and a control group. Vaccinated lambs each received two 1.5-mL S/C doses of a multivalent leptospiral and clostridial vaccine, 4 weeks apart, and animals in the control groups received the same dose of saline. Groups of 12 vaccinated and 12 control lambs were randomly selected in each study for challenge with serovars Hardjo or Pomona. Challenge was initiated 16 weeks following the second vaccination with three daily doses of live leptospires by intranasal and conjunctival routes. Following challenge, urine samples were collected weekly for 6 weeks, for dark field microscopy and leptospiral culture; 6 weeks after challenge the lambs were slaughtered and kidneys collected for leptospiral culture.

RESULTS: In lambs challenged with serovar Hardjo, 8/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive for leptospires following culture, compared with 0/12 lambs in the vaccinated group (p=0.001). In lambs challenged with serovar Pomona, 9/12 unvaccinated lambs had ≥1 urine or kidney sample that was positive following culture, compared with 0/12 lambs in the vaccinated group (p<0.001). Prevention of renal colonisation and urinary shedding, expressed as the prevented fraction, was 100 (95% CI=61.7–100)% and 100 (95% CI=68.3–100)% against challenge with serovars Hardjo and Pomona, respectively, at 4 months after vaccination.

CONCLUSIONS AND CLINICAL RELEVANCE: Use of a multivalent leptospiral and clostridial vaccine demonstrated protection against challenge from New Zealand strains of serovars of Hardjo and Pomona 4 months after vaccination in lambs first vaccinated at 9–11 weeks of age. Further studies are required to assess the duration of immunity against challenge in sheep.     

植物耐干机制研究进展

干旱已成为制约我国农业发展的关键环境因素之一。植物因固着生长,当外界水分因子变化时不能主动逃避胁迫,只能依赖自身机制来抵御外界胁迫,因此,植物的耐干性研究显得十分迫切。本文对前人有关植物耐干研究的工作进行了综述,重点阐明了耐干植物的分类、耐干植物在失水再复水期间形态结构、生理及分子水平上的响应机制,以期为挖掘耐干植物耐干基因、创制耐干种质资源和培育耐干新品种提供新思路。     

Differential Rotation and Dynamics of the Solar Interior

Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.     

Descriptive epidemiology of fracture,tendon and suspensory ligament injuries in National Hunt racehorses in training

Reasons for performing study: While fractures and tendon injuries are known to be important diseases in National Hunt (NH) racehorses during racing, there are no accurate estimates of their incidence in NH training yards. Objectives: To estimate the incidence of fractures and tendon and suspensory ligament injuries (TLIs) in NH racehorses in training; to describe the injuries incurred and to compare injury incidence rates by horse age, trainer, gender and background (ex‐flat vs. ex‐store horses). Methods: Cohort data were collected from 14 UK NH training yards for 2 racing seasons. Daily exercise regimens and details of fractures and TLIs occurring in study horses were recorded. Results: Data were gathered from 1223 horses that spent 9466 months at risk of injury. The fracture incidence rate was 1.1/100 horse months and varied significantly by trainer (P<0.001) but not by gender, age or background. The pelvis and third metacarpal bone (MCIII) were the most common fracture sites, although this varied between racing and training. The TLI incidence rate was 1.9/100 horse months and varied significantly by trainer (P = 0.05) and age (P<0.001) but not by gender or background. However, exstore horses were significantly more likely to have a TLI on the racecourse than ex‐flat horses (P = 0.01). Superficial digital flexor injuries accounted for 89% of all TLIs, the remainder being suspensory ligament injuries. Conclusions and potential relevance: Fractures and TLIs are important causes of morbidity and mortality in NH racehorses in training in England. This study provides accurate estimates of their incidence in this population and provides a baseline against which to monitor the effect of future interventions.     

Modelling the basin-scale demography of Calanus finmarchicus in the north-east Atlantic

In this paper, we report on a coupled physical–biological model describing the spatio-temporal distribution of Calanus finmarchicus over an area of the North Atlantic and Norwegian Sea from 56°N, 30°W to 72°N, 20°E. The model, which explicitly represents all the life-history stages, is implemented in a highly efficient discrete space–time format which permits wide-ranging dynamic exploration and parameter optimization. The underlying hydrodynamic driving functions come from the Hamburg Shelf-Ocean Model (HAMSOM). The spatio-temporal distribution of resources powering development and reproduction is inferred from SeaWiFS sea-surface colour observations. We confront the model with distributional data inferred from continuous plankton recorder observations, overwintering distribution data from a variety of EU, UK national and Canadian programmes which were collated as part of the Trans-Atlantic Study of Calanus (TASC) programme, and high-frequency stage-resolved point time-series obtained as part of the TASC programme. We test two competing hypotheses concerning the control of awakening from diapause and conclude that only a mechanism with characteristics similar to photoperiodic control can explain the test data.     

长胚芽鞘小麦品种耐深播出苗好

综述澳美欧亚非30多国百多家有关研究表明,胚芽鞘长、细、硬、快的小麦品种耐深播、立苗好。从细胞能性角度阐述胚轴划分并澄清小麦胚芽鞘的错位描述及地中茎的混淆定义。图示双胚苗的第二胚芽鞘自然开裂。图释深播地中拔节现象值得春化学者关注。概述胚芽鞘遗传长度、生理长度及环境长度。提到小麦脂肪优质育种问题。对国内麦学界提出3个具有理论或实践意义的建议。