The Canadian Food Inspection Agency (CFIA) is asking home gardeners in British Columbia to dispose of their chrysanthemums this fall, to prevent the spread of chrysanthemum white rust (CWR).
In August, CWR was found in several commercial chrysanthemum growing facilities in British Columbia. Following initial discovery of the diseased plants, the CFIA issued quarantine notices and placed destruction orders on infected plants. Plants and cutting are currently being traced back to their point of origin to determine the source of the outbreak. The disease could have severe trade and economic implications for U.S. commercial chrysanthemum growers. While affected greenhouses and nurseries have been quarantined, a large portion of the crop had already been sold.
Therefore, the CFIA is asking consumers who have purchased a potted chrysanthemum not to plant it in the garden and not compost the plants. Instead, they are asked to dispose of it with household garbage.
In a Canadian Press article, Ken Wong, a plant health program officer with the CFIA explained that “throwing the plants in the garbage once they’re spent, instead of planting them in the garden, would be little cost to the consumer and could save British Columbia’s $4-million chrysanthemum industry.”
The first symptoms of CWR are whitish-yellow circular spots on the upper leaf surface. Spots vary in size from pinhead size to 5 mm across. As the infection develops, the spot becomes sunken and a whitish or buff-colored pustule appears on the undersurface of the leaf.
The disease survives inside the plant, so if a chrysanthemum with CWR survives the winter in the garden, it can spread the disease to other chrysanthemums and surrounding gardens or to commercial growers during the following year. It is also possible that other chrysanthemums in the garden have already been infected. Symptoms are not always obvious in the early stages of infection.