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A polyphasic taxonomic study of a halotolerant micro-organism, isolated from Kuwait salt marsh soil, revealed that this strain represents a novel Nocardiopsis species. The strain produced substrate and aerial mycelium, grew at 28-35 degrees C in salt concentrations of 0-15% and was slightly keratinolytic. Results of the 165 rDNA sequence comparison revealed that strain F100T clustered with strains of the genus Nocardiopsis. This is consistent with other data such as: (i) growth characteristics, i.e. the formation of a white to yellow aerial mycelium and the typical zig-zag form of hyphae, which fragment when ageing; (ii) the presence of DL-diaminopimelic acid and glucose plus ribose in whole-cell hydrolysates; (iii) the presence of phosphatidyl choline, phosphatidyl inositol, phosphatidyl glycerol, phosphatidyl methylethanolamine and diphosphatidyl glycerol in polar lipid extracts; (iv) the presence of menaquinones MK-10(H(0-6)) and MK-11(H(0-6)) in the non-polar fraction; (v) the presence of iso/anteiso-branched plus 10-methyl-branched fatty acids, showing the diagnostic combination for Nocardiopsis spp. of 14-methyl-hexadecanoic acid (18%), oleic acid (9%) and tuberculostearic acid (2%); and (v) the absence of mycolic acids. Analysis of 16S rDNA revealed that strain F100T represents a distinct taxon within Nocardiopsis. Based upon phenotypic differences to other members of the genus, a novel species, Nocardiopsis halotolerans sp. nov., is proposed. The type strain of the species is F100T (= DSM 44410T = NRRL B-24124T).

Date palm trees (Phoenix dactylifera) were found to be infected with Chalara radicicola and Chalara (Thielaviopsis) paradoxa in 1992. Compared with healthy palms, most of the diseased palms appeared to be drought stressed and poorly maintained in landscape settings and nurseries. Water potential studies conducted in growth chambers with 5- to 6-leaf seedling plants subjected to water stress at -2.3 MPa had relatively larger necrotic lesions that developed into cankers, death of buds, and eventually plant death. Tissue necrosis was directly related to water potential. Histological studies showed many necrotic islands of parenchyma tissue in drought-stressed infected plants. Only a few inoculated plants in the growth chamber study died without developing extensive cankers, apparently due to the invasion of the crown or terminal bud by the pathogens. In vitro studies with potato dextrose agar amended with glycerol, NaCl, and KCl to decrease the osmotic matrix-based water potential of the media (-4.25 MPa) resulted in a decrease in the radial growth, biomass, and the sporulation of C. radicicola and T. paradoxa. Solute potential of -0.35 to -1.97 MPa, however, favored the growth of both fungi. Sodium chloride had the greatest effect on the growth characteristics of both fungal species. These studies indicate that in parts of Kuwait where drought and salinity prevail, opportunistic pathogens such as C. radicicola and T. paradoxa could become aggressive and cause serious damage to date palms.

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