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Diffuse light enhanced crop photosynthesis. A more uniform horizontal PPFD distribution played the most important role in this enhancement, and a more uniform vertical PPFD distribution and higher leaf photosynthetic capacity contributed more to the enhancement of crop photosynthesis than did higher values of LAI.

A polyphasic approach was used to describe the phylogenetic position of 22 chitinolytic bacterial isolates that were able to grow at the expense of intact, living hyphae of several soil fungi. These isolates, which were found in slightly acidic dune soils in the Netherlands, were strictly aerobic, Gram-negative rods. Cells grown in liquid cultures were flagellated and possessed pili. A wide range of sugars, alcohols, organic acids and amino acids could be metabolized, whereas several di- and trisaccharides could not be used as substrates. The major cellular fatty acids were C16 : 0, C16 : 1 ω7c and C18 : 1 ω7c. DNA G+C contents were 57–62 mol%. Analysis of nearly full-length 16S rDNA sequences showed that the isolates were related closely to each other (>98·6 % sequence similarity) and could be assigned to the β-Proteobacteria, family ‘Oxalobacteraceae’, order ‘Burkholderiales’. The most closely related species belonged to the genera Herbaspirillum and Janthinobacterium, exhibiting 95·9–96·7 % (Herbaspirillum species) and 94·3–95·6 % (Janthinobacterium species) 16S rDNA sequence similarity to the isolates. Several physiological and biochemical properties indicated that the isolates could be distinguished clearly from both of these genera. Therefore, it is proposed that the isolates described in this study are representatives of a novel genus, Collimonas gen. nov. Genomic fingerprinting (BOX-PCR), detailed analysis of 16S rDNA patterns and physiological characterization (Biolog) of the isolates revealed the existence of four subclusters. The name Collimonas fungivorans gen. nov., sp. nov. has been given to one subcluster (four isolates) that appears to be in the centre of the novel genus; isolates in the other subclusters have been tentatively named Collimonas sp. The type strain of Collimonas fungivorans gen. nov., sp. nov. is Ter6T (=NCCB 100033T=LMG 21973T).

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Since 1992 an increased number of outbreaks of potato brown rot, caused by the bacterium Ralstonia (Burkholderia, Pseudomonas) solanacearum race 3, biovar 2, has been reported in several EPPO member countries, including more northern states like Belgium, France, The Netherlands and the UK. The largest outbreak took place in The Netherlands in 1995, mainly through one heavily infected seed‐tuber line. The bacterium was found in most infested countries in surface water and in the weed Solanum dulcamara growing along waterways. In some countries, tomato was also found to be infected. The history of the so‐called‘low‐temperature’race 3, adapted to more temperate climates (also occurring at higher altitudes in the tropics) is described, together with details on its host range and geographical distribution. Possible origins of the disease in western Europe are discussed, including introduction through import of infected early ware or industrial potatoes from some countries in the Mediterranean area, where the disease is established. The brown rot bacterium has many similarities concerning its biology and epidemiology with some other infectious diseases, e.g. with cholera, and useful comparisons can be made for control strategies. A detailed account on the epidemiology of P. solanacearum and possible prevention and control strategies is presented. These strategies are: (1) responsibility for prevention and control is for the country where the disease occurs; (2) countries where the disease occurs should report outbreaks as soon as possible; (3) early and sure detection and diagnosis of the pathogen are the core of the system; (4) adequate prevention and control measures should be taken after an outbreak; (5) production of healthy seed tubers should be guaranteed and surveys and (laboratory) checks for (latent) infections performed; (6) education of scientific personnel and the public (farmers, traders, advisory service, etc.) is essential. It is foreseen that hygienic measures and avoidance of surface water for irrigation will be key factors in successful control of the disease.