[2] The fungus Puccinia horiana was first described and published by German mycologist Paul Christoph Hennings (1841–1908), when found on the leaves of Chrysanthemum sinense in Honshu, Japan.

[4] It has been found in the United States on several occasions, but early detection and eradication efforts have prevented the disease from becoming established.

[2] Puccinia horiana is a microcyclic, autoecious rust, meaning that the fungus has two known spore stages: teliospores and basidiospores, as well as no known alternate host.

[6] Similar to other microcyclic rusts, two-celled teliospores produce unicellular basidiospores which are then dispersed via air currents.

[6] Under a laboratory setting, it has been shown to both spores need high humidity (50-90% RH) and no less than 5 hours of constant leaf wetness to germinate.

Establishment of CWR may have devastating consequences, it has been shown that Turkey and Poland experience anywhere from 80% to 100% crop loss, which is significant as they are the top producers of Chrysanthemums.

[10] The best form of prevention for CWR is to purchase plants, seeds, and materials from reputable sources to avoid P. horiana from ever entering the facility.

This stops the growth of the fungus, effectively preventing further infection and/or invasion of host tissues [11] APHIS outlines management practices in three different categories for CWR.