Chaozhou and Fujian Oolong Carry Different Red Rust Algae
A survey of 785 composite leaf samples found one alga dominant in Chaozhou and the only one identified in Fujian, at 46.59% and 7.58% positivity.
Red rust, which researchers say is an increasingly significant threat to oolong cultivation, is carried by different algae in China's two great oolong regions, a survey published Aug. 11 finds.
The survey ran in the journal Plant Disease, with Fengnian Wu as lead author and 14 co-authors. It sampled the two regions a Dancong or a Wuyi and Anxi drinker would recognize: Phoenix Dancong country in Chaozhou, Guangdong, and the home of Wuyi yancha (rock tea) and Anxi Tieguanyin in Fujian, set out in Oolong Regions and Origins.
Across 785 composite leaf samples, the alga Cephaleuros turned up in 30.19% overall, at 46.59% in Chaozhou against 7.58% in Fujian. A DNA test targeting a chloroplast gene told the two species apart: C. parasiticus accounted for 95.3% of the Chaozhou detections, while C. virescens was the only species identified in Fujian. No mixed infections were identified anywhere in the survey. A separate 2025 field survey in India, published in Biological Control, found the same two species causing red rust there and tested bacterial treatments against them.
Anthocyanin rose about 62% in the etiolated mutant of Juduozai, a Phoenix Dancong cultivar named for its saw-toothed leaf edges and classed among the aroma types as almond fragrance, 杏仁香, according to 小玲茶业, a Chaozhou tea seller writing on NetEase's self-publishing platform. The paper measured that etiolated mutant, a pale-leaf variant, not the standard bush, and found it answered infection the opposite way from ordinary green-leaf cultivars: those generally lost chlorophyll a and b, with significance varying by cultivar, while the pale mutants gained it, chlorophyll a rising 2.0- to 3.7-fold and carotenoids about 1.5- to 1.6-fold.
Peroxidase and catalase were strongly induced at the edge of each lesion and reduced at its center; superoxide dismutase rose more modestly at the margins. The authors combined the peroxidase and superoxide dismutase readings into a reaction index, sorting cultivars into high- and moderate-response categories, a tool they said could help growers pick more resistant cultivars to plant.
In the Chaozhou samples, histology placed the alga's body beneath both leaf surfaces, with necrosis of the leaf's inner tissue layers. The authors said that suggested deeper invasion by C. parasiticus than by C. virescens.
The paper is paywalled beyond its abstract, and every figure here comes from that abstract. It reports no yield loss and describes no outbreak; whether a cultivar that scores as more resistant actually keeps more of its crop, or tastes any different, is not yet tested.
Sources: Plant Disease, The Cephaleuros spp. Causing Red Rust Disease in Oolong Tea (Camellia sinensis): Genetic Diversity, Pathogenicity, and Host Defense; Europe PMC, record for the same paper, PMID 41678408; Biological Control, Identification and characterization of the pathogens associated with tea red rust in India; 小玲茶业 via 网易号, 锯朵仔是一款怎样的凤凰单丛茶，为何又称为杏仁香 | zh-Hans.