Collate 2L (Ethephon) Drenches Now Registered
The use of ethephon in greenhouse production goes back over 30 years with insights provided by Dr. Peter Konjoian with Florel foliar sprays. Florel and other ethephon product Collate 2L are useful tools in controlling excessive plant growth, improving branching, and avoiding premature flowering in greenhouse plants.
From that initial work, in 2014 a group of researchers lead by Dr. Bill Miller of Cornell University published their findings on using ethephon drenches to control excessive plant growth. Drenches offered similar growth control as a foliar spray, and when used at appropriate concentrations avoided the issue of flowering delay.
Since then, a number of researchers at Cornell University, Purdue University, Michigan State University, Iowa State University, Ohio State University, Virginia Tech, and North Carolina State University have investigated the use of ethephon drenches and refined protocols and recommended rates. For the past 5 years, Fine Americas has supported many of those studies in order to develop a drench use label for Collate 2L. The new use label has finally been approved by EPA. This allows for growers to make Collate 2L drench applications. Legally, Collate 2L is the only ethephon formulation that can be used as a drench.
Collate 2L drenches were highlighted in the 2025 Annual PGR Guide (starting on page 6), along with Collate Use Tips (starting on page 3).
Link to the: 2025 Annual PGR Guide
In addition, in order to use Collate 2L as a drench, it requires that you have the updated use label.
Link to the: Revised Collate 2L label
Brian Whipker
Professor, Horticulture, North Carolina State UniversityBrian E. Whipker is a professor of floriculture at North Carolina State University. He has an appointment split between extension and research, but also teaches the graduate level plant nutrition course at NC State. His specialization is plant nutrition, plant growth regulators, and problem diagnostics. He brings over 30 year of experience in diagnosing grower plant problems.
