Garden mum growers who have been in the industry as long I have should remember bending over and straddling row after row of containerized mums as you carefully pinched the new growth out on a hot, humid June day. After the first thousand or so, you swore that you would never grow them again, but each year like swallows to Capistrano you would set out another 500 to 1000 containerized garden mums in your field. In hindsight, while the work was back-breaking, the money was good in the 80's and 90's and the cash flow helped you to keep your best employees on payroll through the summer.
Today's modern garden mum growers are benefitting greatly from improved genetics and the use of ethephon as a plant growth regulator. Ethephon which is active in the product Florel prevents the premature budding of garden mums resulting in later flowering and better garden mum quality. As a rule Florel (ethephon) is applied at the 300 to 500 ppm rate approximately 10-12 days after sticking the garden mum cuttings. Repeat applications of Florel are made every 10-14 days until approximately eight weeks before the targeted flowering date.
If the Florel is applied correctly, the garden mums will refrain from floral bud development until the influence of the ethephon product (Florel) has begun to wane. There are hundreds of garden mum cultivars on the market and some varieties may have varying degrees of sensitivity to ethephon (Florel). As in the case with all PGRs, trial the ethephon (Florel) on a small subset of the new cultivar first before exposing the entire group to the effects of the PGR. This simple step may prevent a widespread episode of phytotoxicity in this new cultivar of garden mum.
Florel as I've mentioned is routinely applied by garden mum growers throughout Pennsylvania. While there have been very few documented failures of this product to prevent floral bud development, there are a few growers each year that claimed to have witnessed a reduction in product efficacy. To avoid a reduction in the efficacy of Florel and/or other ethephon based growth regulators please read the product label and adhere to all precautions listed on the label.
To maximize the efficacy of Florel on garden mums consider the following:
- When mixing Florel use cool water (less than 75°F) in the spray tank. Warmer water over 75°F causes a premature release of the ethylene which may reduce efficacy in the plant.
- Florel degrades rapidly when mixed in water that has an elevated pH. Adjust the pH of the spray solution to 5.0 with a buffering solution before adding the Florel product to the spray tank. Florel is dissolved in a weak acid, but the acid concentration in the Florel product is insufficient to lower the pH of some water sources. Florel has the greatest efficacy when the spray solution pH is maintained between 3.5 and 4.5. Growers drawing their water from limestone aquifers often see the greatest failure rate of Florel on their garden mums because they failed to reduce the pH of their alkaline spay water sufficiently to slow down the degradation of the Florel product in the spray tank. Adjust the spray solution pH first and then add the Florel for best results.
- Add a spreader sticker to the spray mixture to allow for better coverage on the plant. Florel is not systemic so thorough coverage is the key.
- Spray the Florel to the point of run-off in the morning or late afternoon to maximize absorption potential and lengthen drying times (4 hours is desirable).
- Florel is sensitive to solar radiation and will photo-degrade if exposed to high intensity sunlight.