The Importance of PGR s. Plant Growth Regulators An Integrated Approach. What Do We Use PGR s For? What Not To Use PGRs For. Types of Applications

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1 Plant Growth Regulators An Integrated Approach NJLA Greenhouse Conference June 18, 2014 Dr. George Wulster CFP Solutions L.L.C Rutgers Floriculture Extension Specialist (Retired) The Importance of PGR s PGRs allow a level of pant manipulation at the production and post production level that can improve quality and post production longevity They can be useful tools to enhance what skilled growers can do by manipulating, light, temperature, humidity and inorganic nutrition during production What Do We Use PGR s For? Increase or decrease height Increase branching Delay senescence i.e leaf yellowing, leaf abscission, flower abscission, etc Defoliation Enhance rooting Improve seed germination What Not To Use PGRs For A substitute for an appropriate greenhouse environment for the crop being grown A substitute for appropriate watering and nutrition A substitute for rational scheduling practices A substitute for final inadequate spacing A substitute for the timely spacing of the crop from propagation to sale Types of Applications Sprays Drenches Preplant dips (usually bulbs) Pre-transplant liner soaks It pays to apply these materials at the lowest effective rate and as accurately as possible! When Applying Sprays Plants should be recently irrigated and not water stressed Observe the proper reentry period A-Rest 12 hrs, B-Nine 24 hrs, Cycocel 12 hrs, Bonzi 12 hrs Do not use a spreader sticker unless indicated on the label Make sure your spray equipment is calibrated and working properly 1 gallon per 200 sq ft. 1

2 When Applying Growing Medium Drenches Plants must have a well developed root system Plants should be recently irrigated Use the recommended drench volume for the pot size being treated. Dose = volume x concentration! Correct volumes avoid waste and pollution from drainage Drench rates require much lower concentrations but greater volumes, i.e. Bonzi, 30 PPM foliar spray vs. 1 PPM drench. Preplant Soaks Difficult to manage but try to to estimate necessary volume as closely as possible to avoid disposal difficulties In this case the dose is the concentration x time of exposure Residual volumes can be a problem Mixing Some PGR s can be mixed together and used as tank mixes i.e. Cycocel and B-Nine Try to use material the same day it is mixed Do not mix PGR s with any other pesticides! Do not add additional spreader sticker! Read the label and follow the directions! Compounds For Height Reduction Triazoles The newest and generally most potent chemical class PPM depending upon species and type of application Bonzi (Paclobutrazol), Syngenta Piccolo (Paclobutrazol), Fine Agrichemicals UK Sumagic (Uniconazole), Valent, Concise Fine Chemicals 2014 What s New in This Class? Piccolo seems basically a new product name for Paclobutrazol which has been around since the early 80 s Piccolo 10X is a 4% solution Recent research results (Latimer, GPN Nov. 2004, Grower Talks 2014) indicate that there was no significant difference between Piccolo and Bonzi sprayed at equal rates four weeks after treatment of a herbaceous perennial species Compounds for Height Reduction Pyrimidinemethanol Class Ancymidol, (A-Rest) SePRO, DowElanco 1971 ** Flurprimidol, (Topflor) SePro, DowElanco 1981 Similar but not identical chemistry with Flurprimidol bein somewhat more active. Flurprimidol was tested extensively in the 80 s in the U.S. and Europe but only marketed in Europe until fairly recently While Topflor is a new name a great deal of use information is expected on the label 2

3 Other Compounds for Height Control Cycocel (chlormquat) American Cyanamid 1964, Citadel, Fine Chemicals 2014 B-Nine (daminozide) Uniroyal 1962, Dazide85 WSG, Fine Chemicals 2014 Cycocel damage compounded by application to a water stressed Geranium Cycocel Older materials used at higher rates i.e to 5000 PPM Cycocel can cause leaf yellowing when used at high concentrations or on sensitive varieties Compounds That May Be Labeled For Increasing Height and Branching BAP-10, Configure, Fine Chemicals, Branching only (Cytokinin) Florel 3.9% Southern Agricultural, Collate 21.7% Branching only. Ethylene releasing compound (may reduce height in some species) Fascination: BA plus GA s 4 & 7 Frescoe: 1:1 BA plus GA s 4 & 7 A lot of interest in these for Poinsettias and perennials Antisenescence / Leaf Yellowing Fascination Frescoe Easter, Asiatic and Oriental species can suffer serious yellowing Poor root system, poor spacing, storage may increase the problem Gibberellins ProGibb, FlorGib, Fine Chemicals 2014 Unlike Fresco or Fascination this is GA 3 Biologically more active Elongation and earlier flowering in some plants Used too often to try and undo over applications of height retarding chemicals Using PGR s Effectively While the names are different the active ingredient is generally the same The concentration of the active ingredient may differ significantly from name to name so read the label. Example Florel =3.9% Collate = 21.7% 3

4 Physical and Environmental Factors Sprays are most effective if evaporation rate is low Humid cloudy days, evening, etc. Some chemicals not transported well so sufficient coverage and placement required Triazoles are good example as they are only xylem mobile (sprench) Watering Practices water stress (especially in young plants). Waiting until plants are slightly wilted before watering. Reduces elongation, slows growth. Over watering increases elongation and height control difficulties. Nutritional Management Requires knowledge of the crops nutritional status. Amounts and forms of Nitrogen: Ammonium vs. Nitrate Withholding phosphorus. Fertilizer in abundance increases growth and contributes to height control problems. Light Intensity Low light levels contribute to elongation and height control problems Play important role in leaf yellowing Glazing, and structural members may reduce light levels. Clean or replace glazing in a timely fashion. Minimize shading from plants overhead. Temperature Management Day and night temperature relationships: DIF Try to avoid day temperatures well in excess of night temperatures. Maintaining equal day and night temperatures or lower day temperatures reduces elongation and height of many species. Humidity Management Environments that are poorly ventilated with a high relative humidity increase elongation. Plant tissue is softer and more subject to disease. Ventilation to control humidity will help reduce height and disease problems. 4

5 Mechanical Manipulation Wind, shaking, touching: Best suited for small lots of plants such as tomato seedlings that grow vigorously Roll out bench systems. Management Practices Scheduling : Schedule seeding and transplanting as precisely as possible to avoid holding plants too long after finish or growing plant for too long a period. Environmental management Combine with chemical control, using plant growth retardants as sprays, drenches or dips when it is required When Considering PGR USE Evaluate all available possibilities Base the decision on; cost, plant quality, and best management practices as it relates to your business. PGR Not Always The Answer Improved branching in these Sunpatiens was nutritional, environmental chemicals unneeded Summary PGRs are useful, cost effective plant management tools when used appropriately New names for old ingredients but ingredient concentrations and inert ingredients may differ When you change products do some comparative evaluations between old and new Make sure that your cultural and environmental Ducks are in a row Additional Resources Latimer J. G Growth Regulators for Containerized Herbaceous Perennial Plants, Ball Publishing, West Chicago Illinois Michigan State University PGR website: hrt.msu.edu/floraoe/pgrinfo 5