Analysis of arsenic concentrations and correlation in water, soil and aurum by neutron activation analysis technique: a case study in Bagerhat, Bangladesh.

Arsenic concentrations were measured in water, soil and arum (vegetables) samples using the Neutron Activation Analysis method and a correlation between arsenic concentrations in the samples was investigated. The case study at Bagerhat, Bangladesh revealed that almost all the water samples were contaminated by a hazardous level of arsenic that exceeding the World Health Organization recommended value of 0.05 mg/L for Bangladesh. Arsenic concentration of all the water samples ranged from 0.09 to 0.87 mg/L. The concentrations in soil and aurum samples were found to be in the range of 2.22-35.21 and 0.07-0.73 mg/kg, respectively. A positive correlation between arsenic concentrations in soil and water samples was observed. Aurum sample was found to be contaminated by arsenic to a harmful level if the corresponding water sample was also highly contaminated.

Characterization of Phytophthora capsici Isolates from Processing Pumpkin in Illinois.

This study was conducted to investigate pathogenic, morphologic, and genetic variations among Phytophthora capsici isolates from processing pumpkin (Cucurbita moschata) fields in Illinois. Random amplified polymorphic DNA (RAPD) markers were employed to assess genetic variation among 24 isolates of P. capsici from 10 individual fields at six locations. Unweighted mean pair group analysis clustered isolates into six groups. The genetic distances ranged from 0.03 to 0.45. Inoculation of pumpkin seedlings in the greenhouse revealed that the isolates belonged to six distinct genetic groups differing significantly (P = 0.05) in virulence. Isolates tested exhibited four growth patterns in culture: cottony, rosaceous, petaloid, and stellate. P. capsici isolates, including an ATCC isolate (ATCC-15427), with cottony growth pattern did not grow at 36°C. The mean oospore diameter of A1 mating type isolates was greater than that of A2 mating type isolates. Nine of 24 isolates tested produced chlamydospores in V8-CaCO3 liquid medium.

Fungicide Seed Treatment Effects on Seedling Damping-off of Pumpkin Caused by Phytophthora capsici.

Apron XL LS (mefenoxam) and Allegiance FL (metalaxyl) were highly inhibitory to growth of mycelium of Phytophthora capsici in vitro. Effective dose (ED50) of mefenoxam and metalaxyl for 50% inhibition of mycelial growth, for all five isolates of P. capsici tested, was 0.98 and 0.99 µg a.i./ml of culture medium, respectively. For mefenoxam at 200 µg a.i./ml, sporangium and zoospore germination were reduced by 92 and 96%, respectively, and 21 and 24%, respectively, for metalaxyl. In greenhouse studies, seed treatment with mefenoxam (0.42 ml of Apron XL LS/kg of seed) and metalaxyl (0.98 ml of Allegiance FL/kg of seed) significantly reduced pre- and post-emergence damping-off of seedlings caused by P. capsici in three pumpkin cultivars (Dickinson, Hybrid-401, and Hybrid-698) tested. Thirty-one days after seeding, at inoculum levels of 0, 90, 600, 1,400, and 4,000 CFU/g of soil, the average seedling stands for mefenoxam treatment were 98.4, 93.8, 88.3, 77.8, and 64.8%; for metalaxyl, 99.1, 85.3, 85.8, 73.5, and 59.3; and for the untreated control, 97.5, 55.2, 45.7, 37.0, and 22.9%, respectively. In field trials, the average seedling stands 35 days after seeding were 76.7, 74.7, and 44.9% for mefenoxam, metalaxyl, and untreated control, respectively. Seed treatment with mefenoxam or metalaxyl did not have any significant effect on either seed germination or seedling vigor.

Leaf Spot Disease of Broad Bean Caused by Alternaria tenuissima in Japan.

In April 1999, a leaf spot of broad bean (Vicia faba L.) was observed in commercial fields in Shimane prefecture of Western Japan. Lesions were concentric and brown in color. Older leaves were particularly affected. In later stages of the disease, plants defoliated as leaves blighted from margin to the center. Isolation was made from infected leaf tissue. The isolated fungus produced conidia on V8 medium (2) either in dark or under continuous irradiation of near ultraviolet radiation (NUV) from BLB fluorescent lamps. Conidial chains were unbranched or rarely formed a few lateral branches with a few conidia. The conidia of the fungus grown under continuous NUV were dark and smoothly tapered into the apical beak, and each conidium had a conspicuously thickened primary septum with a constriction of the conidial wall and often a darker median transverse septum. The conidia measured 21.2 to 45.5 µm (mean = 32.9 µm) × 7.3 to 17.7 µm (mean = 11.4 µm ) on V8 medium. Conidia produced on leaves and stem collected from field were similar in size and appearance. The fungus was identified as Alternaria tenuissima based on its cultural and morphological characteristics (2). An isolate was also sent to CABI Bioscience Identification Services (Egham, UK), which also identified the fungus as A. tenuissima. A conidial suspension (107 spores/ml) was prepared and used to inoculate detached leaves and intact plants of broad bean. Intact plants were inoculated by spaying with spore suspension and covered with polyethylene bags for maintaining high humidity. Detached leaves in moist petri dishes were inoculated with drops of spore suspension. Symptom developed on both detached and intact leaves 3 to 4 days after inoculation. Reisolating the pathogen from infected leaves completed Koch's postulates. In June 2000, the leaf spot was observed in all 15 fields surveyed in other areas of Shimane prefecture. In some fields, plants were defoliated and stems and pods were also infected. Isolates of A. tenuissima also were obtained from those fields. This pathogen has been isolated from other hosts in Japan (1). This is the first report of A. tenuissima on broad bean in Japan. References: (1) Anonymous. 2000. Common Names of Plant Diseases in Japan. The Phytopathological Society of Japan, Tokyo. (2) E. G. Simmon. Mycotaxon 37:79-119, 1990.

Phototropism of Conidial Germ Tubes of Botrytis cinerea and Its Implication in Plant Infection Processes.

The germ tubes of Botrytis cinerea showed negative phototropism to near ultraviolet (NUV) and blue (300 to 520 nm) light followed by far-red (700 to 810 nm), whereas red light (600 to 700 nm) induced positive phototropism significantly. Minimum germ tube growth occurred during exposure to negative phototropism-inducing wavelengths, whereas it was maximum under positive phototropism-inducing wavelengths. NUV radiation and blue light that induced negative phototropism of B. cinerea promoted infection-hypha formation on both onion scale and broad bean (Vicia faba) leaf epidermal strips, whereas positive phototropism-inducing red light suppressed it, resulting in a high proportion of germ tubes without infection hyphae. In broad bean leaf infection, the number of infection points and area of necrosis per drop of conidial suspension were higher under NUV radiation and blue light than that of a dark control or leaflets pretreated with NUV radiation and blue light. In contrast, lower numbers of infection points and very small necrotic lesions developed under red light. In the case of red-light-pretreated leaflets, the number of infection points developed were higher, but areas of necrosis did not increase significantly compared with leaflets kept under red light without pretreatment. These results show the importance of phototropism of conidium germ tubes in plant infection.

Inferior vena cava injuries: noninvasive follow-up of venorrhaphy.

BACKGROUND AND METHODS: Recent reports have documented a reduced mortality from injuries to the inferior vena cava (IVC). Few reports, however, have addressed the follow-up of the repaired IVC. From January of 1984 to December of 1995, we prospectively collected data on all patients with IVC injuries at Lincoln Medical and Mental Health Center, an urban Level I trauma center. RESULTS: There were 81 patients with IVC injuries: 60 gunshot wounds, 17 stab wounds, and four blunt injuries. Overall, 45 patients survived (56%). Excluding those who arrived without vital signs and those who did not have emergency department thoracotomies, the survival was 68%. Of the survivors, 38 patients received lateral venorrhaphy, and seven patients underwent ligation. Of the 38 survivors with lateral venorrhaphy, 30 patients (79%) underwent noninvasive follow-up: 13 patients by sonography, 11 patients by computed tomographic scan, and six patients by both modalities. The IVC was visualized in 28 patients (93%) and was found to be patent in 24 (86%). There were four thromboses documented noninvasively, with three cases being confirmed by contrast venorrhaphy. All three resolved with systemic anticoagulation. CONCLUSIONS: We conclude that sonography and computed tomographic scan provide reliable noninvasive evaluation of the repaired IVC. We recommend that all patients with an IVC injury, which has been repaired, undergo evaluation for patency before discharge.