Peronospora sparsa on Cultivated Rubus arcticus and Its Detection by PCR Based on ITS Sequences.

In 1994 to 1996, large yield losses were reported in cultivated arctic bramble (Rubus arcticus) due to berries drying in the middle of the growing season in the entire cultivation area (62° to 66° N) in Finland. Interveinal, angular, purple-red lesions on leaves are associated with the dryberry disease. Cultivations of arctic bramble were inspected in 1995 and 1996, and 69 plant samples and 137 rootstocks were collected and examined for fungi in the laboratory. Perono-spora sparsa was the species most commonly found in all types of samples tested, but Fusarium avenaceum, Cylindrocarpon destructans, and Botrytis cinerea also were detected. P. sparsa was shown to overwinter in the underground parts of arctic bramble. Laboratory tests showed that the two main cultivars of arctic bramble (Pima and Mespi) were susceptible to P. sparsa. Sequences of the internal transcribed spacer (ITS) regions 1 and 2 of the rDNA genes were determined in four and six isolates, respectively, of P. sparsa, and little sequence variability was detected. The corresponding ITS regions of arctic bramble, the above mentioned fungi, a Phoma sp. previously isolated from arctic bramble, and Phytophthora cactorum isolated from strawberry were also determined and compared with the corresponding sequences of P. sparsa. Subsequently, two pairs of primers were designed to the ITS regions that could be used to detect either P. sparsa and Phytophthora cactorum, or only P. sparsa, respectively, by polymerase chain reaction (PCR) using two different types of thermal cyclers ("heated block" Mini Cycler and "hot air flow" Rapid Cycler).

Infection of the Sunagoke moss panels with fungal pathogens hampers sustainable greening in urban environments.

Drought and heat tolerance of the Sunagoke moss (Racomitrium japonicum) and the low thermal conductivity of the dry moss tissue offer novel greening and insulation possibilities of roofs and walls to mitigate the heat island phenomenon in urban environments. However, damage may appear in the moss panels under humid conditions in Japan. In this study we characterized fungi associated with the damaged areas of the Sunagoke moss panels. Fungi were identified by morphology and internal transcribed spacer (ITS) sequence analysis and tested for pathogenicity on R. japonicum (Grimmiaceae) and an unrelated moss species (Physcomitrella patens; Funariaceae) under controlled conditions. Alternaria alternata, Fusarium avenaceum and Fusarium oxysporum caused severe necrosis and death, whereas Cladosporium oxysporum and Epicoccum nigrum caused milder discoloration or chlorosis in both moss species. The fungi pathogenic on moss were closely related to fungal pathogens described from cultivated vascular plants. Ammonium increased severity of fungal diseases in moss. This study demonstrated that fungi can cause economically significant diseases in cultivated moss and hamper commercial use of the moss panels unless appropriate control methods are developed. Use of a single moss clone to cover large surfaces and the air pollutants such as ammonium may increase the risk for fungal disease problems.