12/15/2008
GrowersTalk Production: Fascination for Poinsettias
Joe Moore
Tools are great. The correct tool, along with the ability to use it properly, can lead to impressive results. Improper use of that tool, or using the wrong tool for the job, can lead to disaster. Many poinsettia growers have begun using a plant growth retardant called Fascination (gibberellin GA4+7 and cytokinin benzyladenine, also marketed under the trade name Fresco) that can be used to increase plant height and bract size on poinsettias. Instead of inhibiting the formation of gibberellins in a plant, it increases them. In layman’s terms, it’s a reverse growth regulator. The three most common reasons I see growers using Fascination on poinsettias are to increase bract size on varieties that traditionally have smaller bracts, to reverse the effects of a late growth regulator application on bract size and to increase overall plant height on a crop that’s shorter than desired.
Increased bract size. A 3 ppm spray, applied between November 10 and 15, can be used to increase bract size by as much as 20 to 30%. A single application is generally sufficient for this. An application earlier than the 10th will have a greater increase in overall plant height. One that’s done later than the 15th will tend to not impact overall plant height as much and will have less of an effect on increased bract size. The dates may need to be adjusted slightly forward for the earliest flowering varieties and back for some of the later ones. Since the treated bracts are larger than what may be natural for the variety, there can be a duller appearance to the color. This is generally less noticeable as you get farther away from the date of application. As a general rule of thumb, it takes three to four days for results to begin appearing and 10 days to two weeks to see the full effect. An added benefit is the bract tends to get pulled up on top of the foliage. If you aren’t already spraying calcium chloride as a common practice, at least consider it for those plants being treated with Fascination in order to have plenty of calcium in the larger bracts to avoid edge burn.
Late growth regulator reversal. A common mistake growers make with poinsettias is applying traditional growth regulators too late after the beginning of short days. This results in bracts that are smaller than desired and tucked down into the foliage. For years the only remedy for this situation was to raise the day and night temperatures and wait and pray that the bracts would develop over time. A 3 ppm Fascination spray applied as early as November 1 to the affected varieties can help to pull these bracts up out of the foliage and expand them. Depending upon the amount of overregulation that has taken place, a follow-up spray two weeks later may be necessary. It’s important to give the first application time to fully react before deciding if a second application is necessary.
Increased plant height. The best application for this is a case where a crop needs one or two more inches of final height to reach specs. This can usually be accomplished with a 3 ppm spray in early November. Past history has shown that an early November application, along with normal growing temperatures of 64-66F (17-19C) nights/70-72F (21-22C) days, will add an average of 1 to 2 in. of final height. I’ve seen cases where growers who needed extra plant height have applied Fascination multiple times, two weeks apart. As a general rule of thumb I don’t recommend it except in cases of over growth regulation.
Potential pitfalls. Fascination is an extremely active chemical. A 3 ppm spray is the equivalent of 30 ml in 50 gal., so it’s very easy to make a mistake when mixing up the final spray. I once visited a grower who swore to me that he had applied the correct rate. The 6 in. of space between the first transition bract and the top of the plant and the long, strappy leaves told me otherwise. You’ve heard of “measure twice, cut once.” Well, just remember once you’ve sprayed it on, you can’t change it, so make sure you’re accurate. As always, when possible do some small trials before treating any large areas.
Joe Moore is head grower for Lucas Greenhouses, Monroeville, New Jersey.