Page Banner

United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: Examining Plant Growth Regulator (Pgr) and Herbicial Activity on Container-Grown Crops Produces in Alternative Soilless Substrates

Location: Southern Horticultural Research

2013 Annual Report


1a.Objectives (from AD-416):
The objective of this cooperative research is to characterize and fully measure the efficacy of certain herbicides and plant growth regulators applied to crops grown in various soilless substrates.


1b.Approach (from AD-416):
Different rates of herbicides and plant growth regulators (PGRs) will be applied to container-grown plants produced in various soilless substrates. Using a nutrient recovery system, the effluent and/or substrate at various depths will be collected and analyzed to determine the rate of leaching. In addition, applied radio-labeled herbicides will be analyzed to determine efficacy in these alternative substrates, especially in the root zone.


3.Progress Report:

An Initial Greenhouse study was initiated at the Auburn University Paterson Greenhouse on February 22, 2013. The study evaluated drench applied paclobutrazol (PGR)(Bonzi) to access the affects of alternative substrates on growth and flowering of petunia and impatiens. Results from the study indicate there is possible concern that the efficacy of Bonzi drench is affected by the use of the alternative substrates components of WholeTree or distilled cedar when blended with peat moss (50:50, v:v) and compared to a peatlite industry standard (75:25 peat:perlite, v:v). Results of this initial study will be presented at the Southern Nursery Association Research Conference in Atlanta, GA on August 5, 2013 and published in the conference proceedings.

The initial study was repeated in June 2013 and the results are being analyzed and appear to support the results of the first study. A manuscript of these initial studies is being prepared for submission to the Journal of Environmental Horticulture. Further studies are planned with one study planned for August 2013 on poinsettia, a major fall crop for the greenhouse industry.


Last Modified: 12/18/2014
Footer Content Back to Top of Page