Status of applied biological control of soil-borne plant pathogens

During the last 15 years a great amount of information has been accumulated on the ecology and physiology of soil-borne plant pathogens around the world. Despite this, very few cases of applied biological or cultural control have been reported. Although soil-borne plant pathogens are widely spread and economically important, only a small fraction of plant pathologists and soil microbiologists has devoted full time in the applied phases of biological control. The number of publications on applied control during the last 10 years in two journals surveyed is exceptionally small. The status of applied biological control of root diseases is considerably less favorable than the situation in entomology where much progress has been made during the last 10 years. The status of biological control (narrowly or broadly defined) of soil-borne pathogens is described here and several examples of applied control are cited. Future prospects for research on the ecology and biological control are also discussed.     

CORRELATION OF RADIOGRAPHIC, NECROPSY AND HISTOLOGIC FINDINGS IN 8 DOGS WITH ELBOW DYSPLASIA

Elbow dysplasia is osteoarthrosis/degenerative joint disease due to abnormal development of the elbow joint. The abnormaldevelopment is the result of specific inherited etiologies alone or in combination. This paper attempts to clarify the diagnosis of elbow dysplasia based on the presence of degenerative joint disease by correlating rediographic necropsy, necropsy, and histopathologic results using elbows from 8 German Shepherd dogs. All elbows had radiographic changes consistent with osteoarthrosis/degenerativejoint disease which were identified best on the flexedmedial-lateral projection. Radiographically, a specific diagnosis was made inseven elbows; ununited anconeal process(6) and osteochondrosis (1). At necropsy these lesions were confirmed plus 14 elbows were identified that had fragmented medial coronoid process (6), abnormally shaped medial coronoid processes of fissures in the articualr cartilage of the medial coronoid process (8). additionally, histopathologically there was proliferative synovitis at the radial notch of the ulna and degenerative changes on the proximal, nonarticualr surface of the anconeal process at the site of insertion of the olecranon ligament and joint capsule.Therefore, for screening the elbow joint to identify elbow dysplasia, the recognition of osteoarthrosis/degenerative joint disease on an extreme flexed mediolateral rediograph appears to be sufficient.     

Fibrodysplasia Ossificans Progressiva in the Cat

Clinical, radiographic, electromyographic, and pathologic findings in a cat with fibrodysplasia ossificans progressiva are described. The features of five previously reported cases of this feline disorder are also presented. This disorder affects young adult to middle-aged cats of both sexes. Characteristic clinical features include progressive stiffness of gait, with enlargement of proximal limb musculature. Radiography reveals multiple mineralized densities within the affected musculature. The clinical course is rapid, with development of severe disability within 2 weeks to several months. Electromyographic and pathologic findings suggest that this is a disorder of connective tissue, affecting primarily the epimysium, tendons, and fasciae, and results in marked proliferation of fibrovascular connective tissue, with associated chondroid and osseous metaplasia.     

Analysis of genetic diversity in Agave tequilana var. Azul using RAPD markers

By federal law in Mexico, A. tequilana Weber var. Azul is the only variety of agave permitted for the production of any tequila. Our objective was to assay levels of genetic variation in field populations of A. tequilana var. Azul using randomly amplified polymorphic DNA (RAPD) markers. Ten plants were collected from each of four different fields, with two fields being located in each of two principal regions of Mexico for the cultivation of A. tequilana var. Azul. The two regions are separated geographically by approximately 100km. Genetic relationships between A. tequilana var. Azul and two other varieties of A. tequilana Weber, ‘Chato’ and ‘Siguin’, were also investigated using RAPDs. Among the three varieties, 19 decamer primers produced 130 markers, of which 20 (15.4%) were polymorphic betweenA. tequilana var. Chato and A. tequilana var. Siguin. The results of RAPD analysis suggest that A. tequilana var. Siguin is more closely related to A. tequilana var. Azul than is A. tequilana var. Chato. Among the 40 field selections of A. tequilana var. Azul, only 1 of124 RAPD products (0.8%) was polymorphic and 39 of 40 plants were completely isogenic. This is one of the lowest levels of polymorphism detected to date for the analysis of a crop species, and is proposed to be the result of the promotion of a single conserved genotype over many years due to an exclusive reliance on vegetative propagation for the production of new planting materials. The significance of these results is discussed in relation to breeding programs focused on the improvement of A. tequilana var. Azul. This revised version was published online in July 2006 with corrections to the Cover Date.     

Yield, Oil Content and Fatty Acid Composition Evaluated in Androgenetic Plants in Brassica juncea

Homozygous diploids were obtained through anther culture in Indian mustard, Brassier juncea, cultivar TM-4, Seeds could be harvested from 97 such plants in the A; generation. The androgenetic lines were further selected and the yield and yield components were compared in the A₄ and A₅ generations, Androgenetic lines showed variations for most of the characters studied including seed oil content and fatty acid composition. However, it was possible to recover seven lines out of 25 which were equal in seed yield and three equal in oil content compared TO the anther donor parent TM-4.     

Investigation of the coagulation mechanism of the suspended particulate matter in coastal waters

The granulometry of the suspended matter in various coastal waters collected around the Patras city in Greece, together with the average particle diameters, have been determined during 12 mo by means of a simple, quick, inexpensive and relatively accurate photosedimentometer. The particle size distributions were found to be self-preserving and independent of time, hydrologic regime, nature and amount of particulate materials and particle mobility. The experimental results show that the Brownian diffusion is the factor dominant in the flocculation processes in coastal waters. The flocculation processes of the suspended particles taking place when river water meets sea water were also investigated.     

Measurement needs for developing and assessing ozone-control strategies

The monitoring programs needed to design control strategies differ from those required to assess the impact of the strategies on air quality. The former are short-term and intensive. They are designed to obtain the data required to apply an urban-scale grid model, like the Urban Airshed Model, or a combination of an urban-scale and regional-scale model, like the Regional Oxidant Model, to an area without having to assume important input data. Such measurements include three-dimensional pollutant and meteorological measurements throughout the modeling domain. Detailed and accurate emissions inventories are also required. Model validation should compare not only the O₃ predictions with actual data, but also include comparisons for NO _x , individual volatile organic compounds (VOC), and if possible, additional species such as PAN, H₂O₂, formaldehyde, and HNO₃. To assess the impact of control strategies, long-term monitoring networks that measure O₃, NO _x and speciated VOC are needed. O₃ trends should be examined using robust, meteorologically-adjusted O₃ statistics. Such statistics need to be related to a robust National Ambient Air Quality Standard.     

Behavioral responses of a marine bivalve (Venus verrucosa) to pollution by petroleum hydrocarbons

The effects of exposure to petroleum hydrocarbons (PHC) on the burrowing behavior, valve activities and siphonal and foot reactions of the clam, Venus verrucosa were investigated in a series of laboratory experiments. Such exposure did not significantly alter the burrowing activities of this species. The foot, siphons and mantle folds failed to respond both to low and high concentrations of PHC. After 130 days of exposure to 100 μg L^?1 of water-accommodated fractions of oil, both the response time and the recovery period of the siphonal response to light stimuli were significantly prolonged. Increased valve activities were also recorded. The biological significance of such altered behavior and activities is discussed.