Response of Pisum sativum germplasm resistant to Erysiphe pisi to inoculation with Erysiphe baeumleri, a new pathogen of pea

Abstract

Cultivars, homozygous sources and lines of pea (<I>Pisum sativum</I> L.) resistant to <I>Erysiphe pisi</I> had recently been attacked by another powdery mildew species, <I>Erysiphe</I> <I>baeumleri,</I> in the field and in glasshouse conditions. Inoculation with <I>E. baeumleri</I> was carried out in the glasshouse to evaluate the level of resistance of 16 pea genotypes. Susceptible pea lines produced abundant conidia and cleistocarps on petioles and leaves. Only the genotype Tudor (Cebeco 4119) was found to be completely resistant to <I>E. baeumleri</I>. Nineteen pea genotypes (with gene <I>er-1</I>) were tested to natural infection by <I>E. baeumleri</I> in field screening trials. Only few of them demonstrated a high level of resistance (Fallon, AC Melfort and Joel). Consort R, SGL 2024, SGL 1977 and Franklin were very susceptible to <I>E. baeumleri</I>. Cleistocarps with 1–4× dichotomously branching apices of appendages were formed only on susceptible and very susceptible plants of genotypes SGL 444/2185, Consort R, SGL 2024, SGL 1977, LU 390-R2, Lifter, Highlight, Cebeco 1171 and Carneval R in the field and glasshouse. Susceptible control genotypes without gene <I>er-1</I> (Komet, Adept and Gotik) were attacked in the trials by <I>E. pisi</I> only.