Assessment of risk factors and isolation of Staphylococcus aureus and Escherichia coli from bovine subclinical mastitic milk in and around Gondar,Northwest Ethiopia

Tropical Animal Health and Production - A cross-sectional study with simple random sampling approach was conducted from November 2017 to May 2018 with the objectives of estimating the prevalence of...     

Diplodia scrobiculata found in the southern hemisphere

Diplodia scrobiculata, a latent pathogen of Pinus spp. and other conifers with a limited distribution in the United States, Mexico and southern Europe, has not been reported previously in the southern hemisphere. This is unlike its close relative Diplodia pinea that is found in most parts of the world where pines are native or have been introduced. During an intensive D. pinea survey conducted in Pinus patula plantations in eastern parts of South Africa, a small number of isolates atypical of D. pinea were found. Morphological studies and DNA sequence comparisons showed that these isolates represent D. scrobiculata. Microsatellite analyses suggest that the South African isolates of D. scrobiculata might have originated from California. Pathogenicity tests showed that some of the D. scrobiculata isolates were as pathogenic as those of D. pinea on Pinus radiata and Pinus elliottii.     

Sources of Diplodia pinea endophytic infections in Pinus patula and P. radiata seedlings in South Africa

Diplodia pinea, an opportunistic and latent pathogen, can significantly affect Pinus productivity worldwide. Despite being studied in South Africa for almost 100 years, the source of D. pinea inoculum responsible for seedling infection is unknown. The aim of this study was to determine the role of seed in vertical transmission of D. pinea and to investigate sources of inoculum leading to horizontal transmission to pine seedlings. Surface‐disinfected seeds were inoculated with spore and mycelium suspensions of D. pinea to determine its effect on germination. In addition, isolation of the fungus was performed from surface‐disinfected seeds, asymptomatic seedlings collected from nurseries, plantations where pines naturally regenerate and recently established fields, to assess transmission and incidence of endophytic D. pinea infections. Inoculation of seeds with D. pinea spore suspensions affected speed and rate of germination. The fungus was isolated from surface‐disinfected seeds in only a few instances (2–3%) and was not found in healthy seedlings collected from greenhouses and nurseries, suggesting that vertical transmission of the fungus does not occur or is rare. In contrast, D. pinea was isolated from 40% of seedlings obtained from the understory of mature P. patula trees showing that horizontal transmission from mature to young trees sustains the D. pinea inoculum in South African pine plantations.