Residues of diflubenzuron on horse chestnut (Aesculus hippocastanum) leaves and their efficacy against the horse chestnut leafminer, Cameraria ohridella.

Residues of the insect growth regulator diflubenzuron were quantified on horse chestnut (Aesculus hippocastanum L.) leaves treated with a diflubenzuron 480 g litre(-1) SC, Dimilin. To analyse the samples, an analytical procedure was developed involving a simple extraction step followed by high-performance liquid chromatography on an octadecyl-modified silica column with methanol + 0.

First Detection of Phytoplasmas in Rhododendron in the Czech Republic.

A 10-year-old plant of rhododendron ('Cunningham's White' PS986) with leaf malformation and variegation was observed in Prague in 1997. This plant was micropropagated, and regenerants with severe, mild and no symptoms were obtained. Phytoplasma infection was detected using nested polymerase chain reaction (PCR) in the original PS986 plant and the symptomatic regenerants but not in nonsymptomatic plants.

Hydrocarbon deposition and soil microflora as affected by highway traffic.

The proximity of a busy highway (90,000 vehicles/day) increased the amount of polycyclic aromatic hydrocarbons (PAHs) in soil at the depth of 5-15 cm from 106 ng/g as a grassland background to 3095 ng/g dry soil at the highway verge (a sum of 10 PAH species). The PAH concentration was related to the distance from the source and exhibited a biphasic character, which is interpreted in terms of bimodal distribution of the exhaust microparticles with different rates of deposition. Similarly, the tendency of benz(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene to decrease their proportion with distance from the highway, in contrast to phenanthrene, fluoranthene, pyrene, benzo(a)pyrene, and benzo(g,h,i)perylene, was attributed to their prevalent localisation on the heavier particle fraction.

First Report of Impatiens necrotic spot virus in the Czech Republic.

Impatiens necrotic spot virus (INSV) was found for the first time in the Czech Republic in 1999 in Columnea sp. and Curcuma sp. plants that were imported.

Tomato spotted wilt virus in ornamental plants, vegetables and weeds in the Czech Republic.

The occurrence of tomato spotted wilt virus (TSWV) in horticulture crops and weeds in the Czech Republic has been studied in 1992-1997. During this period TSWV was established in 91 plant species. Virus identity was based on the host range, serology and electron microscopy.