Garrett Owen, PhD Student and Floriculture Technician, Purdue University Roberto G. Lopez, Ph.D., Associate Professor & Floriculture Extension Specialist, Purdue University
Florel, a plant growth regulator (PGR) is typically used as a spray to increase lateral branching, abort flowers and buds, and inhibit internode elongation on a wide range of floricultural crops. These crops include, but are not limited to: Azalea, Begonia, Chrysanthemum, Fuchsia, Zonal and Ivy Geraniums, Impatiens, English ivy, Lantana, Petunia, Poinsettia, Verbena, and Vinca vine (Vinca major).
New growth of zonal geraniums exhibiting Florel phytotoxicity will appear yellow or chlorotic (Figure 1). Leaf margins of young leaves will turn yellow, become yellow between the veins (interveinal chlorosis; Figure 2), and distorted or misshaped (Figure 2 and 3). Symptoms may appear nutritional. However with accurate crop records and routine scouting, diagnosis can be determined.
Most importantly, it is recommended to read the label of any chemical prior to application. Product labels will typically provide growers with recommended application rates of crops previously tested or trialed. In addition, labels will include other valuable information such as: environmental temperatures for best results, concentration and coverage, required protective equipment and clothing, re-entry period/interval, health and safety information, and storage and disposal.
It is important to note, that a single application rate of Florel may not be effective for all floricultural crops and varieties. Therefore, growers should check the label to determine if the desired crop to be treated is listed and follow the recommended application rate. If a specific floricultural crop or variety is not listed, it is recommended to treat a sample of plants with lower than recommended application rates to determine the effectiveness and phytotoxicity potential.