Job offersmore »

Tweeting Growers

Last commentsmore »

Top 5 - yesterday

Top 5 - last week

Top 5 - last month

Exchange ratesmore »

Cool night temperatures induce crown buds in garden mums

Outdoor production of garden mums exposed to several cool nights of temperatures below 60 degrees Fahrenheit induce premature bud formation or crown buds.

Figure 1. Crown buds in outdoor garden mum production. All photos by W. Garrett Owen, MSU Extenson.

Light and temperature influence plant growth and development, and for outdoor garden mum (Chrysanthemum morifolium) production, growers usually rely on natural daylength (photoperiod) and temperature to control crop timing. Garden mums are short-day plants, meaning flower initiation and bud development occurs rapidly when the day length is short and nights are long. However, temperature interacts with photoperiod and can have a greater influence on flower initiation and bud development in mums.

In Michigan, outdoor production of fall garden mums can be challenging, especially when summer nighttime temperatures fall below 60 degrees Fahrenheit. For example, according to the Michigan State University Enviroweather station at Romeo, Michigan, the low temperatures at night averaged 55 F for five days in early July 2018. The several nights of cool temperatures can induce undesirable premature bud formation, which are known as crown buds (Figs. 1 and 2).

One cool night will likely not induce crown bud formation, but several consecutive cool nights can. During this time, flower bud initiation is triggered and the vegetative growth phase ceases, resulting in plants with fewer nodes and leaves, thus finishing small. In addition, stress such as inadequate irrigation and fertility can cause premature bud formation. Therefore, ensure the crop is irrigated as needed and supplied with adequate nutrition of 150 to 250 ppm nitrogen during the vegetative phase.

Figure 2. Crown buds in outdoor garden mum production.

If crown budding occurs, unfortunately there is no corrective procedure. You must be proactive early in the production cycle to prevent early onset of flower buds. Guidelines for preventing premature budding developed by MSU professor emeritus Royal Heins reported using ethephon (Florel or Collate) sprays early in production to delay flowering. MSU Extension recommends growers conduct a small, in-house trial to be certain you achieve the desired response and no phytotoxicity occurs.

Guidelines when using ethephon on garden mums to prevent crown buds:
  • A spray application rate of 500 ppm ethephon is appropriate. Adjust spray water to a pH of 5.0 before adding the ethephon, and add a surfactant if the solution runs off the foliage.
  • Apply the first ethephon treatment about 10 to 12 days after sticking of cuttings, once plants have sufficiently rooted.
  • Repeat seven to 14 days after pinch. Earlier applications (at seven days after pinch) are more important when plants are exposed to cool night temperatures following pinching.
If these guidelines are followed, the number of ethephon spray applications will be dependent on the pot size. According to Heins, mums grown in 6-inch containers need one application before pinch, 8-inch containers require an application before and after pinch, and larger containers require an application before and two after pinch. To prevent delayed flowering, make sure the last ethephon spray application is made eight to nine weeks before the desired ship week.

Also note that pinching the crop will delay flowering and the crop likely will not become revegetated.

Publication date: 8/8/2018



Other news in this sector:

8/17/2018 US: Still a lot unclear surrounding chlorpyrifos ban
8/16/2018 US: Rose rosette disease confirmed in north Louisiana
8/16/2018 Canada to phase out outdoor use of two neonicotinoid pesticides
8/15/2018 New Zealand: Successful partnership prevented establishment of new pest
8/14/2018 US (CA): Chlorpyrifos use down in Santa Barbara County
8/14/2018 US (MA): Fusarium wilt of chrysanthemum
8/14/2018 UK: SCEPTREplus delivers new biopesticide
8/14/2018 "15 percent of pesticide products in Kenya are fake"
8/14/2018 Ethiopia: IPM technical committee for horticulture sector established
8/13/2018 NL: Every day fresh predatory mites in the crop with Bugline 2.0
8/10/2018 US (MI): Pest management in fall aster production
8/10/2018 India: First whitefly attack on crops in Assam
8/9/2018 New production site enables rapid response for gall midge demand
8/9/2018 US: Insect solutions guides available for ornamental growers
8/8/2018 UK: Ash dieback found on three new host species of tree
8/6/2018 UK: New tool against thrips in protected ornamentals
8/6/2018 "Application of Serenade on roses depends on circumstances"
8/6/2018 Pac O is the new name for OHP Plant Growth Regulator
7/20/2018 MSUE to organize course on biological control in protected agriculture
7/19/2018 US: Tick-harboring Japanese barberry could be banned in Pennsylvania



Dear Sir/Madam,

The same phenomena of crown bud formation in chrysanthemum cv. Dendiger also recorded in farmers polyhouses during the month of April-May. Particularly this year we observed very cool night temperatures (17-18 o C) during the month of March and day length of 13 hours. As per your article i can understood that the reason might be cool low temperatures during the month of March. Later on these crown buds failed to open in the months of April and may due to long days and high temp
Dr.K.Ravindra Kumar, Rajahamundry, Andhra Pradesh, India (email) - 8/9/2018 6:38:44 AM

Leave a comment: (max. 500 characters)

  1. All comments which are not related to the article contents will be removed.
  2. All comments with non-related commercial content, will be removed.
  3. All comments with offensive language, will be removed.

  Display email address

  new code