02110nas a2200157 4500008004100000245013700041210006900178260001800247300001400265490000700279520156400286100002101850700002401871700001401895856004301909 2015 eng d00aVariation in pathogenicity among the three subspecies of Phytophthora alni on detached leaves, twigs and branches of Alnus glutinosa0 aVariation in pathogenicity among the three subspecies of Phytoph cDecember 2015 a484–4910 v453 a

Pathogenicity tests were carried out on leaves, twigs and branches of Alnus glutinosa using several isolates of Phytophthora alni ssp. alni, P. alni ssp. multiformis and P. alni ssp. uniformis in vitro. Healthy fresh leaves were collected from disease-free areas and inoculated with mycelium on agar discs or by dipping in zoospore suspensions. In addition, twigs and branches were collected from both disease-free and disease-affected areas, inoculated with mycelium on agar discs and incubated at four temperatures (15, 20, 25, 30°C). All subspecies tested were pathogenic but with varied level of virulence. In inoculation tests on foliage, wounding was a key factor in causing infections: lesions on inoculated wounded leaves were larger than on non-wounded leaves. In the twig and branch inoculation tests, no differences in virulence were observed among the P. alni subspecies in terms of sampling locations, but lesions differed in size according to incubation temperature, with the largest lesions occurring on tissues incubated at 25°C. The work is the first to report foliar necrosis caused by P. alni on A. glutinosa. P. alni ssp. uniformis was the least virulent of the subspecies in branch inoculations. These findings demonstrate that various tissues of A. glutinosa could act as sources of pathogen inoculum and may disseminate alder Phytophthora in natural ecosystems.

1 aHaque, M., M. U.1 aMartín-García, J.1 aDiez, J J uhttp://doi.wiley.com/10.1111/efp.12198