1. Plant Growth Regulators

2. Plant Growth Regulators are naturally occurring or synthetic compounds that affect plant growth and development

3. 3 Types of Chemical Plant Growth Regulators
Growth-inhibiting chemicals
Growth-promoting chemicals
Root-promoting chemicals

4. Plant Hormones “Chemical Messengers”
Auxins
Cytokinins
Gibberellins
Ethylene

5. Rooting Hormones
Auxin, which stimulates rooting, is the main component
IAA (indoleacetic acid)
IBA (indolebutyric acid)
NAA (naphthaleneacetic acid)

6. Rooting Hormones Combination of IBA and NAA Powder Formulations
Hormodin
Hormo-Root
Rhizopon AA
Liquid Formulations
Woods Rooting Compound
Dip’ N Grow

7. Liquid Hormones

8. Powder Hormones

9. Cytokinins Responsible for shoot initiation
Present in rapidly dividing tissue
Benzyladenine (BA)
synthetic cytokinin
increases offset formation in hosta

10. Gibberellic Acid (GA)
Promotes cellular elongation (stretched internodes)
Increases fruit set
Pro-Gibb: Enlarges flowers and elongates peduncles (stems supporting flowers)

11. Ethylene Gas Affects cell division and development Cause flowering
Causes fruit ripening
Causes leaf abscission

12. Plant Growth Retardants (PGRs) are any chemicals that slow cell division and elongation in shoot tissues

13. Why Control Growth? Blow-over Plants out-grow pots
Watering becomes difficult
Increased shipping costs
Leggy, low quality plants

14. Methods of Growth Control
Pruning
costly and time consuming
Genetics
not always available
consumers wary of GMOs

15. Methods of Growth Control
Environmental controls
Low fertility
Negative DIF (Temp)
Water Stress
Brushing, vibrations, and other mechanical disturbances

16. Many growers find chemical plant growth retardants to be an effective and inexpensive method of growth control

17. How do they work? Gibberellin Biosynthesis Inhibitors
Release of Ethylene

18. Notice branching effects

19. Notice height control

21. Synergistic effects of two PGRs

22. Increasing PGR Effectiveness In Non-responsive Perennials

23. Additional Benefits: Control production schedule Increase branching
Induce flowering
Drought tolerant
Pollution tolerant

24. Additional Benefits: Intensely green foliage
Resistant to mechanical damage
Protection from some pests (whiteflies)
Overall higher quality and aesthetic value

25. PGRs for use in Greenhouses:
B-Nine
Cycocel
Bonzi
Sumagic
Florel
A-Rest

26. Chemical PGRs B-Nine (Daminozide) Cycocel (Chlormequatchloride)
labeled for annuals and herbaceous perennials
low activity (relatively safe)
Cycocel (Chlormequatchloride)
not labeled on many crops
causes yellowing above 1500 ppm

27. Chemical PGRs B-Nine/Cycocel tank mixes Synergistic combination
Cycocel 800-1,500 ppm
B-Nine 800-5,000 ppm

28. Chemical PGRs
A-Rest (Ancymidol)
intermediate activity
broad label

29. Chemical PGRs Bonzi (Paclobutrazol) Sumagic (Uniconazole)
broad spectrum label
high activity
Sumagic (Uniconazole)
most active PGR

30. Chemical PGRs Florel, Ethrel, Pistill, (Ethephon)
causes plant to release ethylene
narrow-spectrum label

31. PGR Efficacy Application timing Dosage Target tissue foliage/stems
substrate

32. PGR Efficacy Environmental Conditions Application Technique
environment at application
status of plant
post-application treatment
Application Technique

33. Application Chemical must be accurately measured
ALWAYS wear long sleeves, pants, gloves, and shoes with closed toes when mixing and applying PGRs!!!!!!

34. Media Drenches
specific volume/pot

35. Foliar Sprays
Specific volume/area (0.5gallons/ 100ft2)

36. PGR overdose Example: Bonzi overdose on pansies Ways To Reverse
gibberellins (Pro-Gibb)
high-N nutrition

37. QUESTIONS?