Arthroscopic verification of ultrasonographic diagnosis of meniscal pathology in dogs

OBJECTIVE: To determine the clinical usefulness of ultrasonography for diagnosis of meniscal pathology in dogs. STUDY DESIGN: Double-blind prospective study. ANIMALS: Dogs (n=10) with lameness localized to the stifle. MATERIALS AND METHODS: Sonographic examination of each affected stifle was performed by 1 ultrasonographer unaware of specific historical and clinical data for the dog. Sonographic findings were recorded, but not reviewed until study completion. Arthroscopic examination of the affected stifle was performed within 48 hours of ultrasonography by 1 surgeon unaware of ultrasonographic findings. Arthroscopic findings were recorded, but not reviewed until study completion. Two investigators compared the ultrasonographic and arthroscopic findings at study completion to determine the sensitivity, specificity, positive predictive value, and negative predictive value. RESULTS: Two of the 10 dogs had bilateral stifle evaluation. Twenty-four lateral and medial menisci, with normal and abnormal findings, were examined. The sensitivity and specificity for ultrasonographic diagnosis were 90.0% and 92.9%, respectively; positive and negative predictive values were 90.0% and 92.9%, respectively. CONCLUSIONS: Ultrasonography is highly specific and sensitive for diagnosing bucket handle tears of the medial meniscus in dogs. CLINICAL RELEVANCE: Ultrasonographic evaluation of menisci in dogs is a noninvasive method for accurately and efficiently diagnosing pathology, determining the need for surgical intervention, and providing comprehensive information to clients.     

A pattern in the appearance of cucumber powdery mildew in Dutch glasshouses

An inquiry was held in 1982, 1983 and 1984 to collect information on the survival and dispersal of cucumber powdery mildew. Growers who planted a crop in December, January or February were asked when they observed mildew for the first time in their crop. A gradual increase in the number of infected crops was observed from planting until May. The earliest observations of infected crops were immediately after planting. The weeks of the first observation of mildew, the disease-free periods and the apparent rates of increase of infected crops are presented for various districts. In the districts with the highest crop density (Pijnacker), mildew was generally observed early in the growing season, while the apparent rate of increase of infected crops was higher than in other districts. In the district with the lowest crop density (Northern Netherlands), mildew was observed late in the growing season and the apparent rate of increase of infected crops was low. Possible means of survival and dispersal of inoculum are discussed. It is suggested that overwintering of inoculum is possible because cucumber plants are grown all year round. Dispersal of cucumber powdery mildew is suggested to take place by transportation of infected planting stock, visitors and wind.     

Spatial distribution of weeds in arable crops: are current sampling and analytical methods appropriate?

This paper reviews the literature concerning the spatial distribution of weeds; highlighting the limitations of our current sampling and analytical methodologies, and suggesting how these inadequacies can be addressed. Most research studies have used discrete sampling, i.e. weeds are counted within a quadrat, on a grid basis. Few have mapped weeds at a whole-field scale, either with a resolution appropriate to spraying operations or key ecological processes. Statistical analyses used to describe the data can be divided into two main types, spatially implicit (also at the scale of the sampling unit) or spatially explicit, in which the location of individuals is included in the analyses. Spatially implicit methods can be strongly affected by quadrat size and mean density and are of doubtful benefit. More attention is required to address sampling resolution issues for spatially explicit methods. Our understanding of the formation and dynamics of spatial pattern, as well as predicting the consequences of site-specific management, can be improved with models. Unfortunately, most models consider only newly expanding patches and appear incapable of predicting spatial distributions when an area has been fully invaded. More detailed biological information is required if models are to become more realistic and informative. We also need to ensure that we understand the spatial processes in the context of the whole field environment, to optimize the success of site-specific weed management in the longer term.     

Risk Analysis for Latent Infection of Prune by Monilinia fructicola in California

ABSTRACT The quantitative relationships between incidence of latent infection (ILI) of prune by Monilinia fructicola and wetness duration (WD) for different bloom and fruit developmental stages and different inoculum concentrations were obtained. Three levels of ILI were considered as criteria for low, moderate, and high risks of latent infection, respectively. Seasonal patterns of WD leading to different risk levels of latent infection were obtained for low (IP(L)) and high (IP(H)) inoculum potential conditions in orchards. Longer WD was needed at a resistant than at a susceptible fruit developmental stage to induce similar levels of latent infection. The curves of WD leading to different levels of ILI over the growing season (risky WD curves) were used in risk analysis for latent infection. Multi-year historical WD data from 10 prune-growing locations in California were compared with risky WD curves. The percentage of days (P) with WD leading to a certain risk level of latent infection was calculated for each month from historical weather data. Under the IP(L) condition, the P distributions for low risk of latent infection were higher in March and April than in May and were the lowest in June for most locations. Under the IP(H) condition, the number of days that WD leading to low risk of latent infection in May increased compared with those under the IP(L) condition. The risk analysis approach was evaluated by using separate experimental data as incidence of fruit brown rot obtained from different prune orchards over years. Consistency between predicted overall risk levels of latent infection and observed incidence of fruit brown rot was obtained. The results demonstrated the usefulness of the risk analysis in decision support system for disease management.     

Radiochemical distribution and decline studies with bromoxynil octanoate in wheat

Bromoxynil octanoate labelled with ¹⁴C in the ring or in the cyano-group was applied to wheat seedlings at the two-leaf or fully-tillered stage and at rates equivalent to up to 16 oz a.i./acre. The plants were grown either in environmental chambers under controlled conditions for up to 28 days, or outdoors under field conditions for various periods up to harvest. Initially, elimination of radioactivity occurred more rapidly with bromoxynil-cyano-[¹⁴C]-octanoate than with bromoxynil-ring-[¹⁴C]-octanoate, indicating metabolic attack on the cyano group. Under outdoor conditions with ring-[¹⁴C]-herbicide applied at the two-leaf stage, only 12% of the radioactivity was retained after 28 days, principally in the treated leaves. When application was made at fully-tillered stage, about 33% of the ¹⁴C was retained after 56 days, almost entirely in the treated senescent leaves at the base of the plant. There was very little translocation of the herbicide or of any major metabolite. The level of radioactivity in harvested grain and in straw more than 7.5 cm above the ground was very low, even after very late application of ring-[¹⁴C]-labelled herbicide. The amount of bromoxynil octanoate, together with any metabolite retaining part of the aromatic ring, did not collectively exceed the equivalent of approx. 0.01 parts/million bromoxynil octanoate.     

Antibody-mediated response of pigeons to Argas polonicus larval feeding and characterization of larval antigen

Circulating antibodies to larval Argas polonicus antigen detected in the blood of pigeons by means of ELISA reach their highest level 3-6 days post-tick attachment. During 6-8 days post infestation when most larvae detach from their host, there is an abrupt drop of the antibody level in blood followed by second peak at day 10-15. During the secondary and subsequent infestations the dynamics of the antibody production is analogous, but the maximum absorbance values found are higher with each following infestation. This is in direct correlation with the growth of immune resistance of hosts. The transfer of immunoglobulins of resistant pigeons produces in naive hosts a partial resistance in a statistically significant (P less than 0.01) reduction of the number of engorged larvae, in the shortening of larval feeding period and in the decrease of their mean weight after feeding. However this resistance was significantly (P less than 0.01) less expressed than in naturally resistant pigeons during secondary infestation. The protracted effect on the duration of premoulting period and the percentage of moulted larvae manifested in larvae after secondary infestation was not apparent in molecular weight of approximately 19, 21, 23, 27, 45 and 165 kilodaltons, were recognized by serum of resistant pigeons.     

Binucleate Rhizoctonia sp. AG G causing root rot in yacon (Smallanthus sonchifolius) in Brazil

A new rot caused by a binucleate Rhizoctonia sp. affecting the tuberous root cortex of the domesticated yacon ( Smallanthus sonchifolius ) has been observed in Brazil. Isolates of a binucleate Rhizoctonia sp. were collected from roots with rot symptoms and characterized by the number of nuclei per cell, hyphal anastomosis, RAPD molecular markers, ITS-5·8S rDNA sequence and pathogenicity tests. All isolates had a mean of 1·9–2·2 nuclei per cell and anastomosed with the binucleate Rhizoctonia sp. AG G-tester strain. RAPD analysis was carried out between 11 isolates recovered from yacon and 11 AG (A, Ba, Bb, Bo, C, D, F, G, O, P, Q) standard testers of binucleate Rhizoctonia sp. Genetic similarities of 94·8–100% were observed among isolates of the binucleate Rhizoctonia sp. from yacon and all isolates were genetically more closely related to the AG G tester than other strains according to upgma analysis using RAPD markers. Homologies of complete ITS nucleotide sequences were 100% between binucleate isolates of Rhizoctonia sp. from yacon and the AG G tester. According to pathogenicity tests, the isolates caused typical rot symptoms of yacon tubers 90 days after inoculation     

PCR-based detection of Xanthomonas campestris pathovars in Brassica seed

Xanthomonas campestris is a seedborne bacterium that causes black rot of crucifers. Substantial crop losses may result from the rapid spread of the bacteria under favourable conditions, especially those occurring during seedling production. A PCR-based method has been developed for the rapid and sensitive detection of the pathovars of X. campestris that affect crucifers. Primers were designed to specifically amplify a 619 bp fragment of the hrpF gene from X. campestris . Amplification products were not detected from other Xanthomonas species, or from other pathogenic or epiphytic bacteria occurring on these plants. To avoid false-negative results arising from the presence of amplification inhibitors in plant extracts, primers targeting a 360 bp section of the internal transcribed spacer (ITS) region from Brassica spp. were included in a multiplex PCR. The assay readily detected X. campestris pv. campestris infections in diseased plants and from bacterial colonies isolated on growth media, and was more sensitive and specific than traditional plating methods and a commercially available ELISA. A seed-washing protocol was optimized to allow the detection of a single artificially infected seed among 10 000 healthy seeds using the multiplex PCR.