ANAEROBIC SOIL DISINFESTATION IN MICROCOSMS OF TWO SANDY SOILS.

In recent years, anaerobic soil disinfestation (ASD) has been proposed as an alternative control method of soil-borne plant pathogens. It involves adding a labile carbon source, irrigating the soil to stimulate decomposition of organic material and then covering the soil with air-tight plastic to limit gas exchange. During the ASD process, soil microorganisms switch from aerobic to anaerobic metabolism. As a result, by-products of anaerobic metabolism are released into the soil environment such as various organic acids and gases. These by-products are reported to have a negative effect on survival of soil-borne plant pathogens. However, the efficacy of ASD to reduce soil-borne pathogens in practice may vary significantly. Therefore, we studied the efficacy of the ASD process in two different soils. In addition, it was investigated whether a pre-treatment with an anaerobic bacterial inoculum prior to ASD affected the efficacy of the process. Two sandy soils (dune sand and glacial sand) were inoculated in 2 L soil microcosms. We tested the efficacy of ASD treatment against the potato cyst nematode Globodera pallida. For each soil, three treatments were used: control treatment (no Herbie addition, aerobic incubation), ASD 1 (organic substrate addition, anaerobic incubation) and ASD 2 (organic substrate and anaerobic bacterial inoculum addition, anaerobic incubation). Soil microcosms were incubated in the dark at 20°C for two weeks. We observed that anaerobic soil disinfestation treatments were highly effective against Potato Cyst Nematode (PCN), with pathogen being eradicated totally in all but one ASD treatment (glacial sand ASD2) within two weeks. The relative abundance of Firmicutes (spore-forming bacteria, often fermentative) in total bacteria increased significantly in ASD treated soils. Numbers of these bacteria correlated positively with increased concentrations of acetic and butyric acids in soil water phase in ASD treatments.

Effects of temperature on the flight activity of Graphocephala atropunctata (Hemiptera: Cicadellidae).

Graphocephala atropunctata (Signoret) is the principal vector of Xylella fastidiosa (Wells, Raju, Hung, Weisberg, Mandelco-Paul and Brenner), the bacterium that causes Pierce's disease of grapevine in coastal California. Monitoring the activity of C. atropunctata in the early spring is important for timing insecticide sprays and assessing the potential for disease spread to adjacent vineyards. Trapping studies with yellow sticky traps over 3 yr in Napa Valley, CA, established a significant correlation between early spring trap catch and temperature. Sticky trap catches of G. atropunctata occurred in the springs of 1996-1998 only when temperature was greater than or equal to 14.5 degrees C. In 1997 and 1998, the degree-hours (> 14.5 degrees C) per day from sunrise to sunset during March and April, but not in May, correlated significantly with trap catches. The temperature threshold of 14.5 degrees C in the early spring can be used to improve the timing of insecticidal applications aimed at reducing C. atropunctata populations in vineyards affected by Pierce's disease.

Relevance of aquatic biodegradation tests for predicting degradation of polymeric materials during biological solid waste treatment.

The aquatic biodegradability of cellulose and cellulose acetate with degrees of substitution (d.s.) in the range of 1.5 to 3.0, was compared with the mineralization under laboratory controlled composting conditions. In line with previous observations, it was found that cellulose acetates with d.s. < or = 2.5 were readily mineralized to CO2 in the controlled composting test. The degradation rate was clearly affected by the degree of substitution (d.s. 1.5 > d.s. 2.5 > d.s. 3.0). Surprisingly, however, biodegradation of cellulose acetate materials was not observed in the aquatic Strum test. Modifications of the pH and the inoculum source in an attempt to improve the activity of fungi and actinomycetes in the aquatic environment, did not increase CO2-evolution. It is concluded that the relevance of modified Strum tests is limited for predicting complete biodegradation of polymeric materials during biological waste processing. For evaluation of the compostability of polymeric products or packaging materials, more relevant laboratory controlled composting tests should be used.

Effects of Seasonal and Site Factors on Xiphinema index Populations in Two California Vineyards.

Sampling of Xiphinema index for 2 years (1993-95) in two California vineyards indicated that a greater number of nematodes occurred during the winter months. The number of juveniles increased four-fold from December 1993 to January 1994, indicating a high reproductive rate during this time. Extremely high or low soil temperatures corresponded to low nematode numbers. Samples were taken from 0 to 31 cm and 31 to 62 cm deep both within and between the vine rows. Numbers of nematodes were greatest at the 0- to 31-cm depth in one vineyard with a loamy sand soil, and at a depth of 31 to 62 cm in the second vineyard, which had a silt loam soil. In both vineyards, X. index population densities were greater within the vine row.

In vivo fragmentation of microporous polyurethane- and copolyesterether elastomer-based vascular prostheses.

A previous study showed that microporous, compliant and (bio)degradable vascular prostheses prepared from a polyurethane/poly(L-lactic acid) mixture can function as a temporary scaffold for the regeneration of small-calibre arteries. In this study the mechanism of fragmentation of vascular prostheses made of polyurethane, copolyesterether and blends of either polyurethane or copolyesterether with polymers differing in biodegradability, crystallinity and glass transition temperature is investigated. Animal studies revealed that after 6 wk of implantation only the prostheses made of blends containing a second polymer which was non-elastic at 37 degrees C were fragmented extensively, whether the second polymer was (bio)degradable or not. It is concluded that fragmentation of the prostheses is mainly caused by alternating stresses induced by the arterial pulsations and that (bio)degradation plays a minor role.

[Home treatment of cancer: experiences with ambulatory intra-arterial chemotherapy of liver metastases]. / Onkologische Behandlung zu Hause: Erfahrungen mit einer ambulanten intraarteriellen Chemotherapie von Lebermetastasen.

We have attempted to determine how far it would be feasible to administer intraarterial chemotherapy in patients with colorectal liver metastases on a domiciliary basis. Care of the patients was in the hands of a permanent team consisting of a doctor, a nurse and a psychologist. So far 43 patients have been treated this way. An increased complication rate has not been found during the 225 chemotherapy cycles carried out to date. The median survival of the patients was 14 months, with enhanced quality of life through chemotherapy performed at home.