Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis.

The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT=5-100 keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

Conservative management of a traumatic non-destructive grade II extraperitoneal rectal injury following motor vehicle collision.

Rectal injuries are rare sequelae of blunt force abdominal trauma and are notorious for delayed recognition with resulting high morbidity and mortality. The management of traumatic colorectal injury is mired in old dogma and until recently mandated faecal diversion. Here we present a case of extraperitoneal rectal perforation successfully managed conservatively following blunt trauma.

Comparative Efficacy, Selection of Effective Partners, and Application Time of Strobilurin Fungicides for Control of Cercospora Leaf Spot of Sugar Beet.

In this study, we attempt to optimize the use of strobilurin fungicides by testing the efficacy of azoxystrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin under field conditions, by testing for the most efficient partners in fungicide mixtures, and by testing control efficacy of strobilurin fungicides applied at several application times to determine the better options for disease management. Results showed that trifloxystrobin was the most efficient strobilurin fungicide, followed by pyraclostrobin. Azoxystrobin provided a modest to poor control efficacy, whereas kresoxim-methyl provided only poor disease control efficacy. Mixtures of azoxystrobin and trifloxystrobin with either chlorothalonil or maneb and difenoconazole or flutriafol were tested for their efficacy in controlling the disease. The results showed that the azoxystrobin-containing mixtures provided significantly better control compared with that obtained by single applications of each mixture component. The mixtures of trifloxystrobin with maneb or with difenoconazole or flutriafol provided control efficacy similar to that obtained by single applications of trifloxystrobin, whereas the mixture of trifloxystrobin and chlorothalonil provided significantly lower control efficacy compared with the other trifloxystrobin-containing mixtures tested. For both strobilurin fungicides tested, the calculated ratio between the observed and the expected control efficacy ranged around the value of 1, suggesting additive interactions between the mixtures' components. To determine the most appropriate time for strobilurin fungicides application, trifloxystrobin was applied as the first two, the middle two, or the final two consecutive treatments of six fungicide applications. The remaining fungicide treatments in the spray schedules were carried out by applying the systemic fungicide difenoconazole. Results showed that a higher control efficacy was obtained when trifloxystrobin was applied in either of the earlier applications.

First Report of Phytophthora Root Rot of Sugar Beet, Caused by Phytophthora cryptogea, in Greece.

A severe rot of sugar beet roots was observed in the Amyndeon area of Greece during summer 1998. Infected plants initially showed a temporary wilt, which became permanent, and finally died. Slightly diseased roots showed necrotic spots toward the base, whereas more heavily diseased roots showed a more extensive wet rot that extended upward. Feeder roots also were infected and reduced in number because of decay. Rotted tissue was brown with a distinguishing black margin. In most of the isolations, carried out on potato dextrose agar (PDA), the pathogen obtained was identified as Phytophthora cryptogea Pethybr. & Lafferty Mycelium consisted of fairly uniform, fine hyphae that showed a slightly floral growth pattern. In autoclaved soil-extract medium, chains or clusters of hyphal swellings (average 12 µm diameter) formed. Sporangia were not produced on solid media but were abundant in soil-extract medium. Sporangia were oval to obpyriform in shape, nonpapillate with rounded bases, and varied in size (39 to 80 × 24 to 40 µm). Oospores were plerotic, thick-walled, and averaged 25 µm in diameter. The isolated pathogen, cultured on PDA, could not grow at all at 36°C. The closely related species P. drechsleri Tucker has been reported to cause similar root rot symptoms on sugar beet (3). However, P. drechsleri grows well at 36°C, while P. cryptogea cannot grow at this temperature; this is the major distinguishing feature that separates the two species (1). To test the pathogenicity of the organism, surface-sterilized sugar beet roots (cv. Rizor) were inoculated with 5-mm-diameter PDA plugs containing actively growing mycelium. Sterile PDA plugs were used to inoculate control sugar beet roots. Inoculated roots were kept at 27°C in the dark for 10 days. Extensive decay of inoculated roots developed, similar to decay observed in the field, whereas control roots showed no decay. P. cryptogea was reisolated from rotted tissues. This pathogen has been recognized previously as a cause of root rot of sugar beet in Japan (1) and Wyoming (2). This is the first report of Phytophthora root rot of sugar beet in Greece. References: (1) D. C. Erwin and O. K. Ribeiro. 1996. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN. (2) P. C. Vincelli et. al. Plant Dis. 74:614, 1990. (3) E. D. Whitnew and J. E. Duffus, eds. 1986. Compendium of Beet Diseases and Insects. The American Phytopathological Society, St. Paul, MN.

First Report of Verticillium Wilt of Sugar Beet, Caused by Verticillium dahliae, in Greece.

Wilting sugar beet plants (Beta vulgaris L.) were observed in fields in the Larissa area of central Greece during the summers of 1997 and 1998. Diseased plants, showing general yellowing and epinasty, were sporadically distributed in the fields. As symptoms progressed, the outer leaves wilted and became desiccated. Inner leaves showed marginal and interveinal yellowing. These areas later turned brown and became necrotic. Longitudinal sections of the roots of diseased plants displayed browning of vascular tissues. Fungal isolates obtained from discolored vascular tissues on potato dextrose agar (PDA) medium were identified as Verticillium dahliae based on morphological features (1). Cultures grew moderately fast on PDA at 23°C. Mycelia were hyaline and white to cream colored, becoming black with formation of microsclerotia. Conidiophores were hyaline and verticillately branched, with three to four phialides at each node. Conidia borne on phialides were ellipsoidal to short and cylindrical and mainly one-celled (2.5 to 8 × 1.4 to 3.2 µm). Microsclerotia began to form in 6- to 7-day-old cultures and were dark brown to black and varied in shape and size (25 × 50 to 100 µm diameter). Pathogenicity tests were carried out using the root-dip technique. Two-week-old seedlings (cv. Rizor) were inoculated by dipping roots in an aqueous suspension of 108 conidia per ml for 1 min. Inocula were obtained from 2-week-old cultures grown on PDA at 21°C by adding sterile water to the petri dish, gently shaking to detach conidia from the conidiophores, and filtering through a doublelayer of sterile cheesecloth. Roots of control plants were dipped in distilled water, and seedlings were transplanted to pots and placed in a growth chamber at 23°C with a 12-h photoperiod. Inoculated plants exhibited wilted leaves with interveinal yellowing ≈30 days after inoculation; symptoms were not observed on control plants. V. dahliae was reisolated from artificially inoculated plants. Measurements of yield parameters in healthy and diseased plants showed that the sugar content of diseased roots was significantly reduced, whereas root weight was not affected. Such results agree with a previous report on the effects of the disease on yield parameters (2). However, the disease is of minor importance in Greece mainly because of the low number of infected plants in the fields. This is the first report of Verticillium wilt of sugar beet in Greece. References: (1) Anonymous. 1971. Verticillium dahliae. No 256: Descriptions of Plant Pathogenic Fungi and Bacteria. Common w. Mycol. Inst., Kew, England. (2) J. O. Gaskill and W. A. Krentzer. Phytopathology 30:769, 1940.

First Report of Charcoal Rot of Sugar Beet Caused by Macrophomina phaseolina in Greece.

During the summer of 2000 in the Amyndeon area of northern Greece, sugar beet (Beta vulgaris L.) roots with rot symptoms were observed in many fields. Initially, the plants wilted, and leaves soon turned brown and died. Diseased plants appeared in patches in the field. Brown-black lesions were observed in the external part of the root crown while yellow-mustard colored lesions occurred internally. In advanced stages of decay, masses of sclerotia formed in rotted cavities and roots became mummified. Macrophomina phaseolina (Tassi) Goid. (1) was isolated on potato dextrose agar (PDA) from 30 rotted roots collected in five fields. Cultures produced dark multi-septate mycelium and sclerotia, which were black, smooth, spherical to irregular in shape, and varied in size from 100 µm to 1mm in diameter. Five isolates were evaluated for pathogenicity on surface-sterilized 16-week-old sugar beet roots (cv. Rizor) by placing a 5-mm-diameter PDA plug of actively growing mycelium in wounds made with a sterile knife. Sterile PDA plugs were placed in wounds made in control beet roots. Ten roots were inoculated per isolate. Roots were kept at 25°C in the dark for 10 days. Extensive decay of inoculated roots developed, similar to decay observed in the field, and M. phaseolina was reisolated from rotted tissue. Control roots showed no decay. This pathogen has been previously reported as a root rot pathogen of sugar beet in California, India, and countries of the former USSR. Charcoal rot is of minor economic importance since M. phaseolina attacks mainly weakened plants under conditions of high temperature (2). To our knowledge, this is the first report of charcoal root rot of sugar beet in Greece. References: (1) Anonymous. Macrophomina phaseolina. No. 275 in: Descriptions of Plant Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) J. E. Duffus and E. G. Ruppel. Diseases. Page 347 in: The Sugar Beet Crop. Science into Practice. D. A. Cooke and R. K. Scott eds. Chapman and Hall, NY, 1993.

First Report of Anthracnose on Weeping Willow in Greece.

A serious disease of weeping willow (Salix babylonica) trees in home and public gardens was observed in the Chalkidiki region (northern Greece) during the spring of 1995 and 1996. Purplish-brown or black, small necrotic spots appeared on the leaves and often on leaf veins. Leaves became distorted and fell. Small, light, sunken cankers with dark brown rim and paler center, elongated in shape, appeared on the young shoots and on the leaf petioles. Severely affected shoots lost their weeping habit on which the tree's ornamental value is based. Whitish acervuli covered the leaf spots and the cankers. Masses of conidia emerged from the acervuli under high relative humidity conditions. The conidia were hyaline, clavate to pyriform, two-celled (unequally), measuring 14 to 19 × 4 to 7 µm, and belonged to the fungus Marssonina salicicola (Bres.) Magnus (1), which is the anamorph of the ascomycete Drepanopeziza sphaeroides (Pers.) Hohnel, the cause of anthracnose of weeping willow. The outbreak of the disease can be attributed to the rainy weather (70.5 and 105.5 mm of rain occurred in spring 1995 and spring 1996, respectively) and temperatures of 20°C. The disease is known to cause serious damage in some European countries, Canada, Egypt, Argentina, and New Zealand. This is the first report of the disease in Greece. Reference: (1) I. Vegh and J. Velastegui. Cryptogam. Mycol. 4:345, 1983.

Neutron capture cross section measurement of 151Sm at the CERN neutron time of flight facility (n_TOF).

The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant branch stars. At a thermal energy of kT=30 keV the Maxwellian averaged cross section of this unstable isotope (t(1/2)=93 yr) was determined to be 3100+/-160 mb, significantly larger than theoretical predictions.