Blister rusts in China: hosts, pathogens, and management

Abstract

SummaryChina has 12 taxa of white pines (subgenus Strobus), including species of wide distribution valuable to plantation forestry and species of rare endemics only distantly related to other white pines. The most important forest diseases of these white pines are caused by the blister rust fungi of the genus Cronartium that alternate to telial host species of Ribes and Pedicularis. The most serious infestations have occurred in southwestern China on Pinus armandii and in northeastern China on P. koraiensis. The blister rust pathogen on P. armandii has usually been identified as Cronartium ribicola. Several lines of evidence, however, imply this pathogen on P. armandii is different from a pathogen on P. koraiensis that appears more closely related to C. ribicola in North America, Europe, and other Asian countries. In China, C. ribicola is designated as a quarantine pest. Silvicultural control of blister rust relies on pruning and thinning infected trees, herbicide removal of telial hosts, and chemical treatment of blister rust cankers. Although plantation forestry is important in China, little information is available on the genetics of resistance in Chinese white pines to native blister rust fungi. Challenges and opportunities are identified in forest management and research for disease assessment and control, rust systematics and biology, and genetic interactions in the white pine blister rust pathosystem.

Genetic Resistance to Fusiform Rust in Southern Pines and White Pine Blister Rust in White Pines—A Contrasting Tale of Two Rust Pathosystems—Current Status and Future Prospects

“…However, a more worrisome scenario is the potential re-introduction of other more virulent races of blister rust from China, or the introduction of a second species of blister rust [23]. No information is currently available on the effectiveness of current partial resistances in North American white pines to either of these cases.…”

“…In the case of the WPBR pathogen, these tools offer the potential to examine the worldwide genetic variation in the rust and the potential existence of new virulent or aggressive races that could still be inadvertently introduced into North America. These tools should also help facilitate understanding more about a second species of rust (in China) that appears to be virulent against at least some species of white pines [23].…”

“…The Eurasian white pine species that presumably co-evolved with the WPBR pathogen generally show much higher levels of genetic resistance than do North America white pine species [20,21]. However, in some cases with changing forest management and climate there is also high incidence of rust infection in some of the Asian white pines [22,23], and this may have parallels with the FR pathosystem or implications for the North American blister rust resistance programs. In this paper we will provide information on genetic resistance present in two pine groups and discuss field performance of resistant materials.…”

White pines, Ribes, and blister rust: a review and synthesis

“…Although the frequently observed white pine blister rust pathogen of Europe and North America might share a closest common ancestor, there appear to be additional lineages of ambiguous relationship such as a native European rust (G äumann 1945, 1950) and several Asian rusts (K im et al. 2010; Z hang et al. 2010).…”

Current and future molecular approaches to investigate the white pine blister rust pathosystem

“…(2009) found at least two distinct phylogenetic groups in Asia—one in Japan and the other in South Korea–northeastern China (see K im et al. 2010; Z hang et al. 2010).…”