Lecture 2 Flashcards
Define “Turfgrass Growth Regulator”
• A compound of either organic or synthetic composition which when applied in small amounts results in a change in turf growth or development
Major problems with old PGR chemistries and the settings they were mainly used in
Older chemistries were set up to affect all forms of GA. The only one needed was GA1 but they were all affected. Older chemistries typically used to control growth in out-of-play areas • Areas with low monetary value • High chance for phytotoxicity burn to occur
Differences between Type I and Type II turf PGRs for old classification
Type 1 - slowed overall rates of cell division
Type 2- slowed overall rates of cell elongation
Criteria which determines how a new chemical is classified:
Classified by
- Mode of Action (what do they do?)
- Site of Uptake (leafs, roots etc.)
- Effects on Turfgrass development
Class A:
Late GA synthesis blockers
Class B:
Early GA synthesis blockers (Blocks all forms of GA)
Class C:
Mitotic inhibitors (cell division)
Class D:
Herbicidal with PGR activity
Class E:
Ethylene production enhancement
Class F:
PGR combinations
Site of uptake for Primo and field settings it can be used in
Site of Uptake: Crown
• Use on all turf species
• Can be used on greens,
fairways, tees, roughs
• Apply to actively-growing turf
• Repeat every 3-4 weeks
- Best PGR to maintain Poa annua
explain the ‘rebound effect’ and how to avoid it from occurring
When the plant rebounds (treatment wears off), it comes back stronger than it started and will grow rapidly for a while. Avoid this by having a consistant application schedule.
Describe Morphological changes to the plant in response to GA blockers/inhibitors
Class A (Late GA synthesis blocker)
• Rates of cell elongation slow
• Shorter internodes and compact leaves
• Increased density; same number of leaves but
smaller stem length
• Vertical growth slows
• Resources (carbohydrates) redirected to tillers,
rhizomes, and stolons
• Lateral spread increases turf density
Difference between Embark 2S and Embark TO and main use for the product
Embark TO is 10% as potent as Embark 2S.
While both of them are not to be used on young plants, Embark TO can be used CAREFULLY on putting greens.
Which plant hormone does Proxy stimulate and the main use for the product.
Stimulates Ethylene release.
Main use for the product is to prevent the growth of seedheads in Poa Annua.
What is the main goal when applying Embark TO?
TO suppress seedheads on Poa Annua and to suppress foliar growth on C3 grasses in general.
- It is a mitotic inhibitor
- Inhibits cell division and cell differentiation in meristems
Paclobutrazol
• Site of uptake: roots
• Need to water-in
• Use on cool-season species
• Can be used on bentgrass
greens and fairways
• Mainly for Poa annua reduction
• Apply to actively-growing turf
• Slow uptake (1-2 weeks)
• Effects last 4-6 weeks
Blocks ALL forms of GA..
Embark TO
- 10% a.i. as 2-S
- Site of uptake: leaves (foliar)
- Use on cool-season species
- Safe to use on greens
- DO NOT apply to young tissue
- Poa annua seedhead suppress
- Suppress foliar growth of turf
- Rapid effects (5-7days)
- Effects last 3-4 weeks
Embark 2S
• Mefluidide (Embark 2-S)
• Labeled in mid-1970s
• Site of uptake: leaves (foliar)
• Use on cool-season species
• DO NOT use on greens
• DO NOT apply to young tissue
• Used for suppression of Poa
annua seedheads
• Rapid effects (5-7days)
• Effects last 3-4 weeks
How do Class D products work?
• Inhibit growth by disrupting amino acid
synthesis or fatty acid biosynthesis
• Amino acids - proteins
• Fatty acids - cell membranes
Where do you primarily use Class D products?
Why?
- Out of play areas
- Rough
- Steep Hillsides
- Road Sides
Use is in these areas becuase the label rates usualy cause phototoxicity.
Why would you apply a Class E product?
To slow turf growth and seedhead production.
Mainly used for Poa Annua
Auxin….What does it do?
-Inhibits the growth of tillers, promotes apical dominance. -Maintains active root growth
Cytokinin….What does it do?
-Promotes Lateral shoot growth and Inhibits root growth. -Opposite of Auxin
What is the main function of Gibberellins in a plant?
Cell elongation. Makes the plants tall/long. Induces seed germination and makes plants flower faster.
What does ABA do?
ABA induces stomal closure. It promotes plants to become more drought resistant by decreasing transpiration.
Class B Considerations:
- Mainly for Poa Annua reduction
- Site of Uptake: Roots = slow uptake 1-2 weeks
- Effects last 4 - 6 weeks
- Need to water in (root uptake)
- Apply to actively growing turf
Class A considerations:
- Vertical growth slows
- Carbohydrates (resources) redirected to Tillers, Rhizomes or Stolons
- Lateral Spread increases turf density
- Site of uptake : Crown
- Can be used anywhere
- Apply to actively growing turf
Class C Considerations:
- Inhibits cell division and differentiation in meristems (It stops the plant from growing. period)
- Site of uptake : Leaves
- rapid effects : 5-7 days, Lasts 3 - 4 weeks.
- Used to suppress Poa Annua seedheads
- Some more potent forms (Embark2S) can have very bad phototoxicity problems
- Apply to actively growing turf
Class D Considerations:
- Site of uptake: Leaves or Roots
- Primarily used for low-maintenence areas
- ****Phototoxicity is likely to occur at label rate****
- Use Sub-Lethal rates for PGR results
Class E Considerations:
- Uptake : Leaves (foliar)
- Visual results within 2 weeks
- **Typically mixed with Primo Maxx**
- Suppresses seed heads (poa annua)
- Add fertilizer to minimize potential decrease in rooting
*
Class F Considerations:
- Combinations of PGR’s (PGR Cocktail)
- Uptake : depends on products used
- Growth Suppression and Poa Seedhead Control
- Rebound effect not as bad
