Abstract

GOMEZ, Sandra  and  ARBELAEZ, Germán. Response of three rose varieties to Peronospora sparsa Berkeley infection in greenhouse conditions. Agron. colomb. [online]. 2005, vol.23, n.2, pp.246-255. ISSN 0120-9965.

Healthy 'Charlotte', 'Classy' and 'First Red' variety rose plants grafted onto 'Natal Briar' and 'Manetti' rootstocks and others rooted directly were inoculated with a sporangial suspension of Peronospora sparsa and then incubated for 12 h in a moisture chamber in the dark. After that, plants were kept in normal greenhouse conditions. Symptoms of downy mildew were first observed in plants from the three tested varieties on leaves seven days after sporangia inoculation. The symptoms on stems occurred 17 and 18 d after inoculation in 'Charlotte' and between 21 and 28 d in 'Classy' and 'First Red'. The symptoms on flower buds appeared 14 and 16 d after inoculation in 'Charlotte', 14 d after inoculation in 'Classy' and between 16 and 26 d in 'First Red' plants. Defoliation of affected leaves first occurred in 'Classy' 12 d after inoculation. This reaction was observed in 'Charlotte' from 18 to 28 d and in 'First Red' plants from 15 to 28 d. No interactions regarding incidence of the disease were observed between rose variety and plant stratum. Not all stages of disease development were similar in the different treatments employed in this research; some differences were observed, depending on the rootstock to which the materials had been grafted.

Keywords : downy mildew; pathogenicity cycle; rootstocks; 'Charlotte'; 'Classy'; 'First Red'.

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