This first appeared as “Spotlight on Ornamentals: It’s Mum Season” in the IR-4 Newsletter 41(4):13.
Blooming in September through November and with the prevalence of orange, red, gold and yellow cultivars, chrysanthemums are the epitome of fall. As the third largest single ornamental horticulture pot crop (behind orchids and poinsettias), mums possess an annual wholesale value of over $135 million, with more than 51,500 pots of hardy and indoor florists mums sold annually. This does not include the mums grown as cut flowers and placed in floral arrangements year-round.
Main Disease and Pest Problems
Chrysanthemums are prone to a number of pests & diseases. Some of the common diseases include Pythium and Fusarium root rots, foliar nematodes, leaf spots, viruses, and bacterial blights. Chrysanthemums brown rust and white ruse can cause sever issues during the late stages of production right before plants are harvested for shipping to retail outlets. Pest problems include aphids, thrips, whiteflies, scale, mealybugs, leafminers, mites and foliar feeding caterpillars.
Over the last 10 years, IR-4 has tested more than 140 disease, pest and weed management products to help growers produce healthy high quality mum crops. Much of the research has focused on crop safety, but there were many experiments for the control of bacterial diseases, thrips and whiteflies. Current research projects on mum pest issues include Pythium and Fusarium efficacy along with starting a project on Foliar Nematodes, Some of the researched products include newly registered fungicides, insecticides and herbicides such as Adorn, Flagship and Freehand. While other products tested are already EPA registered, IR-4 is expanding the available uses; examples of these include Conserve, ProStar and Snapshot
Mention of a specific product does not constitute a recommendation for use. As always, consult product labels prior to application and follow all label directions.
Growing mums is an easy task as long as you keep a few things in mind. Plant mums in well-drained, evenly moist soil; this is crucial for healthy mums. Chrysanthemums do not like standing water and will quickly rot if left too wet. If you have a heavy, dry soil, such as hard clay, mums would benefit from added compost and peat moss to loosen the soil. Mums can also be considered heavy feeders; it is a good idea to dive them supplemental fertilizer throughout the growing season, especially if you’re growing them in posts.
For best results from you mum plant, plant in full sun, which will ensure a high bud count and improved plant habits. Although some mums are part shade tolerant, overall your mums will fare better in a full sun environment. Too much shade will cause suffering in flowering habits and stem strength. As with many other flower species, there is a greater risk of foliar fungus and root rot if not planted in full sun.
Planting mums too late in the fall can jeopardize the hardiness of your plants. Planting them too late does not allow enough time for roots to form before it’s time to overwinter them. Ensure that these plants make it through the winder, supply them with a think layer of mulch.
Pruning and Maintenance
Mums are interesting plants because you can manipulate their flower size and shape with careful pruning. One of the most common ways to use this to your advantage is to keep plants pitched and pruned back in the spring before the Fourth of July. Simply pitching the early buds can potentially double the amount of buds your plants will grow in the fall. if you’re growing mums for cut flowers, try disbudding, which removed all of the side buds to encourage one central bloom. Another interesting pruning technique is called the thousand-bloom chrysanthemum, or ozukuri, which grows one extremely large pant and carefully trains the blooms to create a giant, uniform mound of blooms.