Restoration of pasture after topsoil removal: Effects on soil carbon and nitrogen mineralization,microbial biomass and enzyme activities

The restoration of soil biochemical activities after topsoil removal to depths 0 (S₀), 10 (S₁₀) or 20 (S₂₀)cm, and re-establishment of a grass-clover pasture, was studied with Judgeford silt loam, a Typic Dystrochrept, in the Wellington area. Organic matter contents of the S₁₀ and S₂₀ samples were initially 58 and 40%, and biochemical activities, on average, 32 and 20%, respectively of S₀ values. Organic matter content increased only slowly in the stripped plots. Yields of pasture herbage, soil CO₂ and mineral-N production, three indices of microbial biomass, and invertase, amylase, cellulase, xylanase, urease, phosphatase, and sulphatase activities increased more rapidly, but had not reached S₀ levels after 3 yr. The ratios of biomass indices varied with depth of topsoil removed; over the trial, biomass-C to ATP ratios averaged 236, 205, and 168 in the S₀, S₁₀, and S₂₀ samples respectively. Biochemical activities were generally correlated significantly with herbage yields in the S₁₀ or S₂₀, but not in the S₀ plots; organic C or total N contents were not generally correlated significantly with yields over the first 2 yr. Overall, invertase, and then sulphatase, activity appeared to be the best indicators of soil fertility status in this stripped soil.     

Faculty expectations of veterinary students in clinical rotations

Expectations of veterinary students during clinical rotations should be developed with the goal of bettering the veterinary profession as a whole. This article outlines five areas of expectations for the veterinary professional: treating colleagues with respect, providing excellent care for patients and clients, developing and maintaining skill sets to support intellectual curiosity and continued professional development, and improving upon and using self-care and life-balance skills.     

Identification and Discrimination of Pseudomonas syringae Isolates from Wild Cherry in England

A survey of wild cherry (Prunus avium) woodland plantations and nurseries was carried out in 2000/01. Trees with symptoms of bacterial canker were found in 20 of the 24 plantations visited and in three of seven nurseries. Fifty-four Pseudomonas syringae isolates from wild cherry together with 22 representative isolates from sweet cherry and 13 isolates from other Prunus spp., pear and lilac were characterised by physiological, biochemical, serological and pathogenicity tests. Isolates from wild cherry were predominantly P. syringae pv. syringae (Pss), but P. syringae pv. morsprunorum (Psm) races 1 and 2 were also found. Physiological and biochemical tests discriminated Psm races 1 and 2 from other P. syringae isolates. Agglutination and indirect-enzyme-linked immunosorbent assay tests with three different antisera showed that Psm race 1 and race 2 were very uniform and indicated high variability amongst other P. syringae isolates. However, pathogenic Pss isolates could not be distinguished from non-pathogenic isolates of P. syringae on the basis of physiological, biochemical or serological tests. Pathogenicity tests on rooted lilac plants and on micropropagated plantlets of lilac and two wild cherry clones differentiated Pss and Psm isolates and demonstrated a range of aggressiveness amongst Pss isolates. Serological tests could be used as an alternative to the classical physiological and biochemical tests to increase the speed of detection and discrimination of isolates, but pathogenicity tests are still necessary to discriminate the pathogenic Pss isolates.     

The Lodi-Woodbridge Winegrape Commission: a Framework for Implementing IPM

The Lodi-Woodbridge Winegrape Commission Crush District 11 was created by referendum during the summer of 1991. The commission conducts extensive on-farm research trials and demonstration projects in cooperation with the University of California, the California State University system and local growers. The results have been disseminated through a series of regular grower meetings, seminars and an IPM newsletter sponsored by the commission and widespread coverage in the agriculture and general media. Several pest management practices which could reduce pesticide inputs have been promoted by the commission's IPM Program, and others are being further validated or are being researched for applicability to growers in the area. The research falls into two distinct categories. The first category of research is evaluation of the efficacy of recommended practices and includes economic analysis and the collection of biological data to evaluate performance from the perspectives of vineyard ecology, input use, and profitability. Intensive study of 10 growers over 2 years showed a highly variable level of adoption. The yield response to pest control inputs showed increasing returns up to the level of inputs of $375 per hectare after which returns leveled off. The second category of research is the development of alternative practices through on-farm controlled trials. The results of 3 on-farm trials are reported. A cover crop trial showed a reduction of pests in 1995 but no difference in 1994 between the cover cropped and bare soil blocks. Yellow sticky bands significantly reduced the number of leafhoppers in a trial vineyard, but was not as effective as pesticide treatments. The comparison of four alternative weed management techniques demonstrated that the use of an in-row cultivator is more effective than preemergent herbicides or mulch placed along the vine row in controlling weeds. A visual sprayer was shown to reduce the use of contact herbicide. The on-farm approach to all of the research and the in your own backyard nature of the meetings has created the sense of ownership for the growers that has been instrumental in achieving grower support. The public nature of the information provided by the commission and grower members to all winegrape producers implies a recognition among members of their interdependence and the long-term benefits of reducing pesticide use as a group. The recognition of interdependency is crucial for any group trying to form an IPM district.     

Correction to: Incidence and characterization of the presence of phytoplasmas in Fraxinus uhdei related with Ash Yellow disease in Colombia

Journal of Plant Diseases and Protection - In the article mentioned above, an author’s name was misspelled.     

Effect of hydrogen cyanamide,mineral oil and thidiazuron in combination with tip pruning on bud break,shoot growth and yield in ‘Bourjasotte Noire’, ‘Col de Damme Noire’ and ‘Noire de Caromb’ figs

Commercial fig production is relatively new to the Mediterranean-type climate Western Cape Province of South Africa. A lack of lateral branch development impedes tree structure development and therefore adequate yields of quality fruit. The chemical rest breaking agents, Lift^® (thidiazuron 3 g L⁻¹) at 6%, Dormex^® (hydrogen cyanamide, 520 g L⁻¹) at 4%, mineral oil at 4% and a combination of mineral oil and Dormex^® at 2% each were evaluated in a split plot design in combination with tip-pruning vs. no-pruning to overcome apical dominance and increase complexity (Experiment 1). During the 2008/2009 season, an additional investigation was conducted to evaluate the use of thidiazuron and hydrogen cyanamide for harvest scheduling (Experiment 2). Dormex^® at 3% and Lift^® at 6%, were applied to dormant trees on 30 June 2008, 3 August 2008, 15 August 2008 or 30 August 2008. In general, Lift^® can be used to increase the number of buds breaking in ‘Bourjasotte Noire’ and ‘Col de Damme Noire’, while tip pruning decreased bud break with a resultant increase in shoot length. Dormex^® and oil combined decreased bud break in these two cultivars but was effective on ‘Noire de Caromb’. Where bud break was increased the resultant N + 1 shoot length was decreased. RBAs increased the number of fruit in both the breba and main crop of ‘Noire de Caromb’, but decreased fruit size of the breba crop. Our data are not conclusive as to what the reason for low lateral bud break might be but leans towards strong AD in seasons with 400 Utah CU or more, but might include some delayed foliation response in seasons with less than 200 Utah CH.     

Gene for pathogenicity and ability to cause the hypersensitive reaction cloned from Erwinia amylovora

A genomic library of Erwinia amylovora isolate T was constructed in the cosmid pLAFR3 and maintained in Escherichia coli. Clones were transferred individually by conjugation into the non-pathogenic isolate P66 of E. amylovora. Transconjugants were screened for restoration of pathogenicity to pear by stab inoculation into sections of immature pear fruits. Three clones complemented P66 restoring pathogenicity and ability to cause the hypersensitive reaction (HR) in Phaseolus vulgaris. Restriction mapping and hybridization experiments showed that the three clones had a common 3·7 kb fragment of E. amylovora DNA. Sub-cloning and insertion mutagenesis with Tn5-lac confirmed that a determinant of pathogenicity and ability to cause the HR (hrp gene) was located on a 2·1 kb HindIII/BamHI fragment within the common DNA. Hybridization experiments using the 2·1 kb HindIII/BamHI fragment as a probe demonstrated that the hrp gene was located in the chromosome of isolate T and that homologous sequences were present in the non-pathogenic isolates P66 and S. Clones which restored hrp function did not affect the growth of isolate P66 in minimal or nutrient-rich media. Transconjugants of Pseudomonas syringae pv. phaseolicola race 1 harbouring the hrp gene(s) cloned from E. amylovora did not cause the HR in susceptible cultivars of bean but symptoms developed more slowly than in the absence of the clones or with pLAFR3 alone.