A method for in vitro production of conidia of Elsinoe veneta and the inoculation of raspberry cultivars

Abstract

Su in mar)Conidia of two isolates of Elsinor venefa were consistently produced in vitro by a 3-stage culture system in which spai-sely sporulating microcolonies produced on corn meal agar were used to 'seed' C'mpek-Dox V 8 juice agar. E. veneta then spoi-ulated on this medium i f discs wet-e floated mycelium uppermost on sterile distilled \later f'or 24 ti at 25°C. Both isolates also produced microconidia in vifro.Only the growing apices of raspberry canes were susceptible to infection. Of 12 genotypes inoculated in the glasshouse, a red raspberry derivative of Rirbirs coi.eu~/r5, Ehl RS 2769/9, was the most resistant and the black raspberry selection SCRl 815286 and cv. Malling Delight were the most susceptible. Of four red ra5pbert-y cultivars inoculated in the field cc'. Malling Orion was the most susceptible. Inoculated flowers and debeloping fruits produced malformed fruits bccnuse int'ccled drupelcts were sniallcr o r slower to ripen than uninfected ones. 111 trod tic t ion Elsinoe \eneta (Burkh.) Jenkins (conidial state: Sphaceloiiia necator (Ell. & Ev.) Jenkins & Shear) causes cane spot or anthracnose on the canes and leaves of cultivars of the genus R~i D u 5 , most notably cultivars of black I-aspberrv ( R . occidentulis L.), red raspberry ( R . idueus

The histology of lesion development in raspberry canes infected by Elsinoe veneta

“…The patterns of infection of cortex, polyderm and phloem tissues and the host responses to them were similar in all the genotypes examined, despite a marked contrast in numbers and sizes of lesions found previously (Williamson et al, 1989). The low incidence of infection and small lesions shown by EMRS 276919 may be due to resistance expressed at a very early stage in the infection process.…”

“…in water to 'seed' plates of Czapek-Dox V8 juice agar containing full nutrient supplement (Cz V8) and then floating discs of agar mycelial weft uppermost on distilled water for 24 h. Conidia were released abundantly in water by brushing the agar discs (Williamson et a/., 1989). The apex and first-expanding leaf of fast-growing young raspberry canes were inoculated with a suspension of 1.0 x loh conidia/ml applied with a small camel-hair brush.…”