Phytophthora hibernalis - a new pathogen on roses

摘要

Reqierunqsprasidium Giessen, Dez. 51.4 Pflanzenschutzdienst Hessen, Wetzlar, Germany At the end of March 2007 an unusual twig blight was observed on imported containerized grafted Rosa cv. Chevy Chase. The roses had been overwintered outdoor under a plastic sheet to prevent frost damage. When the sheet was removed in spring, most of the roses looked dead and the rest had dark violet to black lesions at the base of the stems close to the soil surface (Fig. 1) and also on the twigs up to 30 cm in height. The root-stock of these plants looked healthy. The discoloured regions of the twigs were clearly distinct from the apparently healthy sections of the twigs. Removal of the discoloured bark exposed brown lesions in the wood beneath. Above the discoloured regions the twigs had died. Soon after sampling all the diseased roses were removed from the container area and destroyed.