Host plants of the powdery mildew fungus Podosphaera xanthii in Taiwan

Abstract

Podosphaera xanthii is presently considered as one of the powdery mildew fungi with the broadest host range. Confusion is caused by taxonomical and nomenclatural changes of the host plants and the fungal parasite. Based on the list of powdery mildews from Taiwan from 1998, an updated list of host plants of P. xanthii in this country is presented. New hosts from Taiwan are wild and horticultural herbs and woody plants collected between 2011 and 2020. Fifteen plant species were found to be the host of P. xanthii based on new collections of the anamorph and internal transcribed spacer (ITS) sequences. Among them, Cuphea carthagenensis, Cuphea hyssopifolia, Erigeron bellioides, Mazus pumilus, Phyllanthus tenellus, Salvia farinacea, and Sphagneticola trilobata were new hosts worldwide, whereas Bidens pilosa, Eclipta prostrata, Pouzolzia zeylanica, and Torenia fournieri were new hosts in Taiwan. Four further plant species were confirmed as known hosts (Emilia sonchifolia, Sesamum indicum, Trema orientalis, Zinnia elegans). Asteraceae contained most host species in Taiwan, which appeared proportional to the high species diversity in this plant family. The second highest host diversity in the Cucurbitaceae, however, was not proportional to plant diversity. Although the fungus is able to cause similar symptoms on a broad range of hosts, certain host species showed specific responses to infection. In some species, infection remains limited to old leaves, whereas in other species, only young leaves or mainly stems are infected.

Morphological and molecular characterization of Podosphaera xanthii, causal agent of powdery mildew in husk tomato and watermelon

“…The results suggest that there is morphological variation of P. xanthii based on their host of origin. In a study carried out in Taiwan, Yeh et al (2021) reported notable morphological variability of P. xanthii in the anamorph stage, which was influenced according to the host where it was isolated; similar results were determined in this study.…”

New Records of Powdery Mildews from Taiwan: Erysiphe ipomoeae comb. nov., E. aff. betae on Buckwheat, and E. neolycopersici comb. nov. on Cardiospermum halicacabum

“…In the present study, the occurrence periods of the PMs in the winter and spring imply they prefer mild weather instead of excessively high temperature (up to 35 • C) in summer, and it is suggested that the PMs in the subtropical regions may stay in a quiescent state in their hosts during hot summers. However, chasmothecia are rarely formed in subtropical and tropical environments [23,47,77,94]. Thus, the reservoirs of the PMs on all their possible hosts as mycelia or other structures are crucial for their survival and for the infection in the next season.…”

Evaluating the Efficacy of the Fermentation Formula of Bacillus velezensis Strain Tcb43 in Controlling Cucumber Powdery Mildew

“…There are more than 200 species of powdery mildew hosts in Taiwan, but the pathogens are different and specific. Among the economically important crops affected are melons, members of the Solanaceae family, leguminous crops, and various fruit trees, among others [4]. Cucumber powdery mildew is an important leaf disease and seriously affects yields.…”