Photo courtesy of Fine Americas

Greenhouse Management: Why isn’t my ethephon PGR working effectively?

Dudley Dabbs: As we approach summer and warmer temps, we hear from more growers asking for support on ethephon products (such as Collate and Florel), which are used for increased branching. Many of the larger commercial greenhouses prefer overhead boom applications for ethephon where the 6X more concentrated Collate has a better fit than Florel. The increased concentration of the Collate formulation eliminates the boom overwatering issue with Florel because it takes so much of the less concentrated formula to achieve the desired results. In addition, Collate increases storage and shipping cost while reducing the number of containers needed to do the job.

Every year we hear about failures — whatever product they’re using, we get the call. We have identified two of the most common pitfalls to avoid.

First, make sure your spray tank water is buffered so that the pH is between 4 and 5. Ethephon is stable at low pH, but at higher pH levels, it will destabilize and not be as effective.

Second, avoid high temperatures at application. That means making late evening or early morning applications during warm weather so that you can avoid doing applications at temperatures higher than 79° F.

We have confirmed this through Fine Americas-funded studies conducted by Dr. Roberto Lopez at Michigan State University.

If you make sure these two factors are addressed, you can avoid failures and increase your chance of success with ethephon PGRs.

GM: What’s the best way to start tank mixing PGRs?

DD: As growers mature in their PGR use, they often advance to tank mixing two or more PGRs together to achieve the results they’re looking for. Before doing that, it’s very important that you understand what the different PGRs do. Understanding the different plant growth regulators’ modes of action is the first step toward success with tank mixing.

GM: How can I successfully use the Trifecta tank mix I’ve heard about?

DD: Some very experienced users are tank mixing three PGRs — Dazide, Collate and Configure — to achieve the utmost precision: Dazide for height control, Collate for branching and Configure for branching through a different mode of action. These growers have coined the phrase Trifecta as a nickname for this three-way combination.

Using these three products together does achieve excellent results, but it is not for the inexperienced PGR user. It takes great knowledge and careful management to succeed. One of the most critical aspects of mixing PGRs is proper application timing. Using these three PGRs together really optimizes your outstanding plant production if you can achieve the proper plant growth stage timing.

You get the plant to maintenance growth, but you also encourage it to branch and fill out the pot, growing wider than taller. You end up with a tight internodes and lots of breaks — a really tight plant. You get that way quicker and with only one application. These plants have nice architecture while maintaining plant growth.

If you’re really interested in delving into more enhanced PGR use, Dr. Joyce Latimer of Virginia Tech University, Dr. Brian Whipker of North Carolina State University, and Dr. Roberto Lopez of Michigan State University will be presenting a Branching Out with PGRs seminar sponsored by Fine Americas at Cultivate’19, Sunday, July 14, at 2:45 p.m. And you can also attend Managing and Improving Plant Vigor with PGRs on Monday, July 15 with Latimer and Whipker at 9:45 a.m.