Impact of weather variables and season on sporulation of Phytophthora pluvialis and Phytophthora kernoviae

Phytophthora pluvialis and Phytophthora kernoviae are the causal agents of important needle diseases on Pinus radiata in New Zealand. Little is known about the epidemiology of the diseases, making the development of control strategies challenging. To investigate the seasonality and climatic drivers of sporulation, inoculum traps, consisting of pine fascicles floating on water in plastic containers, were exchanged fortnightly at five sites in P. radiata plantations between February 2012 and December 2014. Sections of needle baits were plated onto selective media and growth of Phytophthora pluvialis and P. kernoviae recorded. To explore the generalizability of these data, they were compared to detection data for both pathogens from the New Zealand Forest Health Database (NZFHDB). Further, equivalent analyses on infection of Rhododendron ponticum by P. kernoviae in Cornwall, UK allowed the comparison of the epidemiology of P. kernoviae across different host systems and environments. In New Zealand, inoculum of P. pluvialis and P. kernoviae was detected between January–December and March–November, respectively. Inoculum of both species peaked in abundance in late winter. The probability of detecting P. pluvialis and P. kernoviae was greater at lower temperatures, while the probability of detecting P. pluvialis also increased during periods of wet weather. Similar patterns were observed in NZFHDB data. However, the seasonal pattern of infection by P. kernoviae in the UK was the opposite of that seen for sporulation in New Zealand. Phytophthora kernoviae was likely limited by warmer and drier summers in New Zealand, but by colder winter weather in the UK. These results emphasize the importance of considering both environmental drivers and thresholds in improving our understanding of pathogen epidemiology.     

Aboveground biomass,transpiration and water use efficiency in eucalypt plantation fertilized with KCl,NaCl and phonolite rock powder

Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha^?1 of KCl compared with that of 2125 kg ha^?1 of phonolite rock powder (equivalent to 170 kg ha^?1 of K₂O in both treatments); (2) application of 139 kg ha^?1 of NaCl compared with that of 183 kg ha^?1 of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.

     

Use of touch-down polymerase chain reaction to enhance the sensitivity of Mycobacterium bovis detection.

The confirmatory diagnosis of Mycobacterium bovis (M. bovis) in animal samples is carried out by culture in Stonebrink media. However, culture is very slow because of the extremely long duplication time of the bacillus and difficult because of the scarcity of bacilli in diagnostic samples. This study describes the development of a single-tube touch-down polymerase chain reaction (PCR) protocol for the detection of M. bovis using primers that target the IS6110 element. Spiked water and milk as well as routine diagnostic samples (milk and nasal swabs) from M. bovis-positive cattle were tested. This protocol allows the rapid and sensitive detection of M. bovis in bovine samples by enhancing the sensitivity of standard PCR amplification.     

Lactation curves in captive Iberian red deer (Cervus elaphus hispanicus)

This study examines milk production and the effect of milk production and sex of calf on body weights and gains of red deer calves and hinds of the Iberian subspecies (Cervus elaphus hispanicus). Milk production was assessed in 14 hinds by weighing calves before and after suckling and by adjusting these values to the Gamma function. Gamma estimates of total milk production up to d 105 were similar to the amounts computed directly from double weighing. Hinds showed two types of lactation curve: 1) the standard mammal lactation curve, with an asymmetrical peak at wk 2 to 4 (Type I) and 2) decreasing curves with no peak (Type II). Although there was great interindividual variability, hinds with Type I curves showed a trend to produce more milk than those with Type II. The type of curve did not seem to affect weight variables of the calf or those of the dam. Calves that gained more weight consumed greater amounts of milk (P<.05). Males were heavier than females at birth (P<.05), but males did not differ from females in their weight at 105 d, milk consumption, and gain. Gender did not affect hind weight, but dams of male calves showed a trend to be lighter (P = .063) at d 105 than dams of female calves. Our results suggest that suckling differences found in other studies between male and female calves may not involve differences in milk production, although other rearing costs seem to affect hind weight losses. They also suggest that the curve type may not depend only, as reported, on the nutrition plane.     

Prevalence of parasite eggs and cysts in faeces from dairy cows in Colombia

Summary When 1, 711 bovine faecal samples from 113 farms in eight dairy areas of Colombia were examined for the presence of helminth eggsFasciola hepatica eggs were found in the faeces from 60% of the farms and samples from animals kept above 2,000 m. Strongyle eggs were found in faeces from 82% of the farms and in 18% of the samples.

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Resumen Se examinaron 1.711 muestras fecales provenientes de 113 fincas, localizadas en ocho zonas lecheras de Colombia. Se encontraron huevos deFasciola hapatica, en el 60% de fincas y muestras fecales de animales sobre los 2,000 m.s.n.m. Se encontraron tambien huevos de estrogilideos en heces del 82% de fincas y en el 18% de las muestras examinadas.

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Résumé La recherche d’oeufs d’helminthes sur 1711 échantillons de fécès provenant de 113 fermes de 8 districts laitiers de Colombie a permis de noter la présence d’oeufs deFasciola hepatica dans 60 p. 100 des fermes et échantillons originaires d’animaux vivant à plus de 2,000 m. Des oeufs de strongles ont été notés dans les fécès provenant de 82 p. 100 des fermes et 18 p. 100 des échantillons.

     

Levels of some reproductive diseases in the dairy cattle of Colombia

Of 4,144 serum samples collected from cows on 113 farms from eight areas of Colombia 3.3% had positive and 8.8% inconclusive titres to Brucella abortus, 21.7, 6.3, 1.6, 0.6 and 0.7% of cows had positive titres to Leptospira serovars hardjo, pomona, canicola, icterohaemorrhagiae and grippotyphosa respectively. Questionnaires completed on 110 farms revealed that 6, 2.5 and 4.6% of cows had had metritis, aborted or retained their placentas respectively in the previous 12 months. Trichomonas foetus and Campylobacter fetus were isolated from 13.7% and 15% of the bulls sampled on 103 farms. Six and two bulls had inconclusive and positive titres to Brucella abortus. Eight and 23 bulls had positive titres to pomona and hardjo. The results were discussed and remedies for control suggested.     

Morphologic, Molecular, and Pathogenic Characterization of Diaporthe phaseolorum Variability in the Core Soybean-Producing Area of Argentina

ABSTRACT Isolates of the Diaporthe/Phomopsis (D/P) complex were collected in the main soybean producing area of Argentina during the 1996-97, 1997-98, and 1998-99 growing seasons. Twenty-three morphologic characters related to type of colonies, stroma, pycnidia and conidia, presence of perithecia, and asci length were studied by principal component analysis (PCA). Genomic DNA were analyzed by the random amplified polymorphic DNA (RAPD) technique. From both studies, 18 isolates were identified as D/P complex and grouped in four major taxa: (i) Diaporthe phaseolorum var. meridionalis, (ii) D. phaseolorum var. caulivora, (iii) D. phaseolorum var. sojae, and (iv) Phomopsis longicolla. In addition to distinguishing interspecific and intraspecific variability, molecular markers allowed the detection of differences among isolates within the same variety. Pathogenicity was assayed in the greenhouse, by the toothpick method, inoculating the D/P isolates to soybean genotypes carrying different resistance genes (Rdc1, Rdc2, Rdc3, and Rdc4) against soybean stem canker (SSC). Pathogenic analysis distinguished two main groups: (i) the SSC-producing isolates, including D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora, and (ii) the non-SSC-producing isolates, including D. phaseolorum var. sojae and P. longicolla. Cultivar RA-702 (susceptible control) was compatible with both D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora isolates; meanwhile, Tracy-M (Rdc1 and Rdc 2 genes) was incompatible with D. phaseolorum var. meridionalis but compatible with D. phaseolorum var. caulivora isolates. The fact that Rdc1 and Rdc2 together (as in Tracy-M) confer an almost immune reaction to all assayed isolates of D. phaseolorum var. meridionalis but were ineffective against the D. phaseolorum var. caulivora isolates evaluated suggests that the virulence or avirulence genes in D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora are different. Moreover, physiological races of D. phaseolorum var. meridionalis were detected by using differential soybean genotypes carrying distinct single Rdc genes. As far as we know, this is the first report on the existence of physiological races of D. phaseolorum var. meridionalis in South America. Selective pressure due to deployment of resistant host cultivars may have changed the frequency of the virulence or avirulence genes within the population of D. phaseolorum var. meridionalis. On the whole, our results show that pathogenic variability of D. phaseolorum in the core soybean-producing area of Argentina is higher than previously recognized.     

Oral administration of yeast, Saccharomyces cerevisiae, enhances the cellular innate immune response of gilthead seabream (Sparus aurata L.)

The effects of including lyophilised whole yeast, Saccharomyces cerevisiae, in the diet on the seabream innate immune response were investigated. Gilthead seabream (Sparus aurata L.) specimens were fed four different diets for 4 weeks: a commercial diet as control and the same diet supplemented with 1, 5 or 10 g/kg yeast. After 1, 2 and 4 weeks, serum complement titres, as a humoral parameter, and phagocytic, respiratory burst, myeloperoxidase and natural cytotoxic activities of head-kidney leucocytes, as cellular parameters, were evaluated. The results showed that yeast supplements enhanced all the latter responses, but not the humoral response. This enhancement was dose-dependent except for the cytotoxic activity that was only stimulated by the lower dose of yeast assayed. As yeast cell walls are able to enhance the seabream cellular innate immune response, these results support the possible use of whole yeast as natural inmunostimulants in common fish diets.