A supplemental label for Fresco has been approved and now includes application as a substrate drench or a foliar spray. Until now, products that contain gibberellins (GA) and benzyladenine (BA) could only be applied as a foliar spray. There is some evidence to suggest that a substrate drench provides a more uniform growth response than a foliar spray. Fresco drench application guidelines include:

• A sufficient volume so that the solution uniformly reaches the entire pot volume.
• Application to moist, but not wet media.
• Reducing the rate by 25 to 50 percent when applied through sub-irrigation.

Generally, GA products are applied to ornamental plants that are shorter than desired, which can occur when plant growth retardants are applied at an excessive rate or volume. These products can also be used to delay leaf yellowing on lilies, delay flower senescence of bulb crops and increase poinsettia bract size. As with all plant growth regulators, growers are encouraged to perform their own small-scale trials to determine appropriate rates and application strategy. In many instances, an application rate of 2 to 5 ppm provides a desirable growth promotion response.

For more information on Fresco, visit the Fine Americas website. For more information on plant growth regulator applications, visit the Michigan State University Extension Floriculture website.

Photo credit: Erik Runkle, MSU

Dr. Runkle's work is funded in part by MSU's AgBioResearch.