Powdery mildew (Erysiphaceae) on Calibrachoa hybrids in Germany, Nicaragua and the USA
2015
Brielmaier-Liebetanz, Ulrike | Field, A. E. | Warfield, C.Y. | Braun, U.
Cultivated Calibrachoa hybrids were previously thought to be resistant to powdery mildew, but infections have been recently encountered in Germany, USA and Nicaragua. The exclusive development of asexual morphs (anamorphs) led to the question as to which powdery mildew species might be involved as causal agents. Based on inoculation experiments and molecular sequence analyses, it was determined that powdery mildew infections on Calibrachoa in Europe (Germany), North America (USA), and Central America (Nicaragua) were found to be caused by the plurivorous Podosphaera xanthii. The anamorph is a typical Fibroidium characterized by conidia formed in chains (catenescent), containing distinct fibrosin bodies. Calibrachoa powdery mildew caused by P. xanthii could be easily transferred to cucumber, squash and Verbena ×hybrida and vice versa in the latter case. Attempts to inoculate petunias failed. In addition to P. xanthii, two additional powdery mildew species were found infecting Calibrachoa ×hybrida in Germany. The first, characterized by having lobed hyphal appressoria and conidia formed singly, can be assigned to Pseudoidium neolycopersici, and the second species, readily distinguishable by its very long conidiophores, conidia in chains with sinuate outline and nipple-shaped hyphal appressoria, belongs to Euoidium longipes. In the course of the current examinations, E. longipes was also found on Verbena ×hybrida, which represents the first record of this species on a non-solanaceous host.
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Editeur Mae Fah Luang University, Institute of Excellence in Fungal Research
ISSN 2229-2217Cette notice bibliographique a été fournie par Julius Kühn-Institut
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