First report of gladiolus rust caused by Uromyces transversalis in Cuba

In March 2010, rust lesions were observed on leaves of hybrid gladiolus plants in a garden located in the outskirts of Santiago de Cuba city and in a flower production field in Güira de Melena (Santiago de Cuba and Havana provinces respectively).The incidence of the disease in both locations was near 100% with varying levels of severity. Lesions bearing uredinia were bright orange, variable in shape from globose to oval to transversely elongate. Uredinia (1-3 mm long) were scattered or grouped, orange, elliptical to irregular, and arranged transversely across the leaf (Fig.1). Urediniospores were bright yellow gold, ovate to oblong, and measured 16-26 x 13-19 µm (Fig. 2). The urediniospore wall was hyaline, minutely echinulate and 1.5-2.5 µm thick. Telia were scattered, dark brown, elliptical, bearing nonseptate, light-to-brown teliospores that measured 22-25 x 14-18 µm with an apical thickening measuring 2-4 µm. Paraphyses were densely aggregated (Fig. 3).

Three Uromyces species have been reported in gladiolus: Uromyces transversalis, U. gladioli and U. nyikensis (Hernández, 2004): U. transversalis has been reported in Africa, Europe, Australasia, several South American countries, United States and Mexico. Uromyces gladioli has been reported from several African countries, Argentina and Uruguay, while U. nyikensis has been only reported in Zambia and is not considered of economic importance (Hernández, 2004. U. transversalis has transverse sori that develop across the width of the leaves and are up to 3 mm long, producing telia with paraphyses (teliospores measuring [17.5-] 20-25 [-34] × [14-] 15-17.5 [-21] µm). Uromyces gladioli (teliospores measuring 20-37[-40] × 18-26 µm) and U. nyikensis (teliospores measuring 19-32 × 14-22 µm) lack transverse sori and produce telia without paraphyses(Smith et al., 1992). On the basis of these characters, the rust was identified as Uromyces transversalis (Hernández, 2004). This is the first report of U. transversalis causing gladiolus rust in Cuba.