AN OUTBREAK OF ANAL FIBROPAPILLOMATOSIS IN COWS FOLLOWING RECTAL EXAMINATIONS

An outbreak of fibropapillomatosis following rectal examination for pregnancy and involving the anus and to a lesser extent the rectum in a herd of beef heifers in western Victoria is described. Almost half the herd were involved at one time; most lesions regressed with the following 16 weeks. Lesions varied from 0.2 mm diameter polyps up to large multiple lesions up to 7 x 5 x 2 cm with a broad base. The presence of lesions did not affect the body condition or health of the animals.     

Comparison of capillary ear blood and arterial blood to validate capillary sampling as an accurate assay of blood gas in swine.

Capillary sampling in swine can be performed as an accurate assay of arterial blood gases. Studies with swine provided results similar to, or slightly more favorable than, those reported for human beings, depending upon which cutaneous technique was used on human beings. On the basis of free flow or arterilization of the cutaneous sample and of the correlation between capillary and arterial pH, CO2 partial pressure (PCO2), and O2 partial pressure (PO2) values, the capillary sampling technique of complete incisement of a 2-mm section from the tip of the warmed porcine ear could be a substitution technique for arterial blood sampling. Free flow with this technique was maximized and high correlation coefficients (r) for pH (r = 0.96), PCO2 (r = 0.82), and PO2 (r = 0.90) capillary-arterial values (n = 37) were obtained.     

Rust-proofing wheat for a changing climate

This paper offers projections of potential effects of climate change on rusts of wheat and how we should factor in a changing climate when planning for the future management of these diseases. Even though the rusts of wheat have been extensively studied internationally, there is a paucity of information on the likely effects of a changing climate on the rusts and their influence on wheat production. Due to the lack of published empirical research we relied on the few published studies of other plant diseases, our own unpublished work and relevant information from the vast literature on rusts of wheat to prepare this overview. Three broad areas of potential risks from a changing climate were described: increased loss from wheat rusts, new rust pathotypes evolving faster and the reduced effectiveness of rust resistances. Increased biomass of wheat crops grown in the presence of elevated CO₂ concentrations and higher temperatures will increase the leaf area available for attack by the pathogen leading to increased inoculum production. If changed weather conditions were to accelerate the life cycle of a pathogen, the increased inoculum can lead to severe rust epidemics in many environments. Likewise should the effects of climate change result in more conducive conditions for rust development there will also be a corresponding increase in the rate of evolution of new pathotypes which could increase the rate of appearance of new virulences. The effectiveness of some rust resistance genes is influenced by temperature and crop development stage. Climate change may directly or indirectly influence the effectiveness of some resistance genes but this can not be ascertained due to a complete lack of knowledge. Since disease resistance breeding is a long term strategy it is important to determine if any of the important genes may become less effective due to climate change. Studies must be made to acquire new information on the rust disease triangle to increase the adaptive capacity of wheat under climate change. Leadership within the Borlaug Global Rust Initiative (BGRI) is needed to broker research on rust evolution and the durability of resistance under climate change.     

Tape depth and germination method influence patterns of salt accumulation with subsurface drip irrigation

Subsurface drip irrigation (SDI) can result in accumulation of soluble salts at or near the soil surface. In the southwestern USA, rainfall is usually inadequate for stand establishment, thus supplemental irrigation is necessary. Use of sprinklers to minimize salt concentrations near the soil surface is an alternative to using SDI for stand establishment. Our objective was to evaluate the effects of germination method (irrigation with SDI or sprinklers), depth of SDI tape (0.18 and 0.25 m), and irrigation water salinity (1.5 and 2.6 dS m⁻¹) on salt and Br distribution after each of two consecutive growing seasons. Treatments consisted of factorial combinations of these three factors. Bromide was used to trace salt accumulation from the drip tape. After season 1, the highest salt concentrations (ECe up to 11 dS m⁻¹) were in the top 3 cm of soil. Below 3 cm, soil EC dropped significantly and remained constant to 1.05 m. Similarly, Br concentrations were highest in the top 3 cm of soil. The mass of salt and Br recovered in the top 3 cm were significantly affected by tape depth, and water EC significantly affected salt mass. Salt present in the soil after season 1 adversely affected crop emergence in season 2, where SDI was used for stand establishment. After season 2, the highest salt and Br concentrations were at about 25 cm depth, probably due to 210 mm of rainfall that occurred near the end of the growing season. There were no significant differences among treatments in the mass of either salt or Br in the top 3 cm or 16 cm of the soil profile after season 2. Timely rainfall, transplanting rather than direct seeding, and changing bed geometry can reduce dependence on sprinklers for stand establishment.