pgrs and tgrs

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PGRs and TGRs

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PGRs and TGRs. Different Modes of Action- Type I and Type II. Type I growth regulators inhibit cell division. Type I growth regulators are foliar absorbed. Different Modes of Action- Type I and Type II. - PowerPoint PPT Presentation

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Page 1: PGRs and TGRs

PGRs and TGRs

Page 2: PGRs and TGRs

Different Modes of Action- Type I and Type II

• Type I growth regulators inhibit cell division.

• Type I growth regulators are foliar absorbed.

Page 3: PGRs and TGRs

Different Modes of Action- Type I and Type II

• Most Type I Growth regulators are older materials that cause some phytotoxicity on grass.

• Mefluidide (Embark) is utilized more than any other type I growth regulator, but it yellows and thins turf when used during hot weather conditions.

Page 4: PGRs and TGRs

Different Modes of Action- Type I and Type II

• Maleic hydrazide (MH-30, Royal Slo-Gro) is one of the oldest growth regulators used on turf, and causes extensive yellowing.

Page 5: PGRs and TGRs

Type I- Growth Regulators

• Embark (mefluidide) is also used to inhibit seed head formation of Poa annua to improve the appearance and playability of fairways.

• The rate used for seed head suppression is 1/12-1/16 of the growth regulation rate.

Page 6: PGRs and TGRs

Type I- Growth Regulators

• Timing is critical- must be within two weeks of flowering to be effective. • Usually about two weeks after the first mowing

is a good time to apply.

• Some yellowing may still occur, but this can be reduced by using products like Ferremec.2

• If you are going to try it, read the label thoroughly!

Page 7: PGRs and TGRs

Type II Growth Regulators

• Type II growth regulators work by inhibiting biosynthesis of gibberellin.

• Since, gibberellin causes cell elongation, little or no elongation of cells occurs when GA is inhibited.

Page 8: PGRs and TGRs

Type II Growth Regulators

• Type II growth regulators include: • Cutless (Flurprimidol),

• Limit (amidochlor),

• Primo (trinexapac- ethyl)

• TGR Turf Enhancer (paclobutrazol)

• http://www.uhsonline.com/prodframe.php

Page 9: PGRs and TGRs

Type II Growth Regulators

• Type II growth regulators generally are less phytotoxic, and some actually have benefits other than reduced growth.

• Amidochlor (Limit) is less damaging to turf than type I growth regulators, but still should not be used on high maintenance turf.

Page 10: PGRs and TGRs

Type II Growth Regulators

• Many superintendents have tried Type II growth regulators as a means of reducing Poa annua on their golf courses.

• http://www.andersonsgolfproducts.com/st_poaannua.asp

Page 11: PGRs and TGRs

Type II Growth Regulators

• Growth in Poa annua is reduced more than in Agrostis palustris, giving the creeping bentgrass a chance to spread into the territory held by Poa annua . (1,2,3,4,5)

• Cutless, TGR Turf Enhancer and Primo have all been used in this way with varying degrees of success. (1,2,3,4)

• Cutless and TGR Turf Enhancer are most effective in suppressing Poa annua but they also cause yellowing which may be unacceptable.

Page 12: PGRs and TGRs

Type II Growth Regulators

• Other possible benefits of type II Growth Regulators include:

• Reduced mowing- the duration of suppressed growth varies considerably (usually 4-7 weeks) depending on species, environmental and growth factors. (1,2,3,4)

Page 13: PGRs and TGRs

Type II Growth Regulators

• Increased shoot density- more tillering (1,2,3,4)

• Reduced water use- lower ET rates have been observed with Primo, Cutless and TGR.

• However, Primo was the only material that enhanced turf quality during dry down in one study. (4)

• Longer disease suppression with contact fungicides ??

Page 14: PGRs and TGRs

Type II Growth Regulators

• Flurprimidol and paclobutrazol have been shown to reduce dollar spot disease incidence somewhat on creeping bentgrass.

• Improved green speed at mowing heights > 1/8” (research doesn’t back this theory up)

Page 15: PGRs and TGRs

Cutless

Page 16: PGRs and TGRs

Type II Growth Regulators

• There are also some possible negative effects of Type I and II Growth Regulators. They include:

• Reduced uniformity- regulation of growth can vary between grasses resulting in non- uniform appearance.

Page 17: PGRs and TGRs

Type II Growth Regulators

• “rebound effect”- after the growth regulator wears off, there is often a flush of growth resulting in reduced turf quality and a need for increased mowing. • Primo and Embark have caused this response.

• Increased weed problems- some weeds,like goosegrass, have less of a reduction in growth rate than turfgrasses.

• Moreover, some weed species like crabgrass increase in shoot production due to increased tillering caused by some PGRs. (5)

Page 18: PGRs and TGRs

Type II Growth Regulators

• Slower recuperation from injury?

• Increased susceptibility to some diseases? Type I growth regulators have shown to cause increased disease problems.(2)

Page 19: PGRs and TGRs

New Classification Scheme for TGRs

• A new way to classify growth regulators has been developed using classes A,B,C, and D.

• Class A materials are GA inhibitors that interfere with GA synthesis late in the biosynthetic pathway. • Only Trinexapac-ethyl is in the category.

Page 20: PGRs and TGRs

New Classification Scheme for TGRs

• Class B materials interfere with GA synthesis early in the biosynthetic pathway. • Fluprimidol and paclobutrozol are included in this class.

• Class C materials inhibit mitosis. • Hyradazide, mefluidide and amidochlor are in this category.

• Class D materials are phytotoxic (can kill plants) but have a growth regulating effect at very low rates. • Glyphosate (Roundup) and chlorsulfuron (Telar) are examples.

Page 21: PGRs and TGRs

A “New” Growth Regulator for Turf

• Proxy (ethephon) recently received a label for turfgrass use.

• Ethephon works by releasing ethylene into turfgrass leaves. (2)

• Ethephon has a more subtle action than type I or type II inhibitors with no noticeable change in growth habit for about 2 weeks.(2)

Page 22: PGRs and TGRs

A “New” Growth Regulator for Turf

• Ethephon does not fit into the A,B,C,D scheme of classification either.

• Ethephon has no rebound effect like Primo and Embark do.

Page 23: PGRs and TGRs

A “New” Growth Regulator for Turf

• Proxy may be very effective in battling Poa annua with growth reduction as high as 90% with an average of 38% over seven weeks

• Bentgrass growth reduction with Proxy was a maximum of 50% and a 14% average over seven weeks. (2)

Page 24: PGRs and TGRs

A “New” Growth Regulator for Turf

• Proxy is not labeled for greens- further testing needs to be done.

• Proxy is also labeled for Poa annua seed head supression.

• Nick Christians claims that Poa pratensis treated with Proxy changed in form to an almost stoloniferous growth habit, which might improve wear tolerance.

Page 25: PGRs and TGRs

Fertility and Growth Regulators

• It is generally best to keep fertility levels somewhat higher on turf treated with growth regulators than on non- treated turf because:

• Growth regulation effects seem to be enhanced at higher fertility levels.

• Higher fertility levels help to mask the chlorosis that sometimes appears when growth regulators are used.

Page 26: PGRs and TGRs

Seedhead Management & Plant Growth Regulators

• Poa is not a single, uniform turf species.

• It has a large number of turf subspecies or biotypes.

Page 27: PGRs and TGRs

Seedhead Management & Plant Growth Regulators

• Poa annua can range from: • annual types that die each spring following a period of

intense seedhead formation.

• Biotypes that live for several years and flower later in the season for longer periods of time.

• It is impossible to predict which biotypes you have on your course.

• The many biotypes is the #1 reason its so hard to predict precisely when the seed will form.

Page 28: PGRs and TGRs

Seedhead Management

• At courses where Poa is tolerated, reducing seed heads makes a difference.

• Most seed head management has relied on a combination of cultural practices and applications of PGR’s.

• The cultural practices used to improve mowing when seed heads are present include brushing and vertical mowing.

• Proxy is becoming the preferred chemical for seed head management.

Page 29: PGRs and TGRs

Seedhead Management & PGR’s

• Mefluidide is well known for its ability to slow down or stop seedhead formation.

• Mefluidide is used to inhibit Poa Seedhead formation on golf courses.

• Under optimal conditions, applications can result in 85 – 90% Poa annua seedhead suppression.

• There are some drawbacks of using this product.

Page 30: PGRs and TGRs

Drawbacks of Using Mefluidide

• Varying Turf Response

-Using PGR’s to slow seedhead formation came into use in the 90’s, but results vary greatly by location.

-Seedhead suppression will last from 3 – 6 weeks.

-To keep seedheads formation consistently low, you will need to increase the rate gradually after each application.

-Success depends greatly on the skill of the superintendent to adapt the program to his or her course.

Page 31: PGRs and TGRs

Drawbacks of Using Mefluidide

• Timing of the First Application

-Because this product does not affect seedheads that already exist the first application needs to be made two weeks before the first flush of seedheads.

-The first application will need to be at different times in different location or different climates.

Page 32: PGRs and TGRs

References

• 1. Christians, Nick, Creative Uses for Turfgrass Growth Regulators, USGA Green Section Record, September-October 2001, p.11-13.

• 2. Dernoeden, Peter. Creeping Bentgrass Management. Sleeping Bear Press, Inc. Chelsea, MI, 2000.

• 3. Diesburg, Kenneth. A New Growth Regulator for Golf Course Turfgrass. Golf Course Management. November 1998.

• 4. Fermanian, Tom. Managing Bentgrass Fairway Growth with PGRs. Grounds Maintenance. May 1997.

Page 33: PGRs and TGRs

References

• 5. Fry, J.D. Plant Growth Regulators May Help Reduce Water Use. Golf Course Management. November 1998.

• 6. Lowe, Todd et al. Some weeds Flourish Under Growth Regulators. Golf Course Management. September 1999.

Page 34: PGRs and TGRs

LINKS

• http://www.grounds-mag.com/managing.htm• http://virtual.clemson.edu/groups/hort/sctop/TUR

FSec/weedsci/weedsci5.htm• http://www.cp.us.novartis.com/products/specialty/

PrimoWSB.shtml• http://link.springer-ny.com/link/service/journals/1

0088/bibs/38n4p1028.html• http://www.turf.uiuc.edu/itf/tips/tt97-2.html

Page 35: PGRs and TGRs

LINKS

• http://www.hort.iastate.edu/pages/news/turfrpt/1999/greenpoa98.html

• http://www.msu.edu/user/rogersj/laplata.html

• http://edis.ifas.ufl.edu/scripts/htmlgen.exe?DOCUMENT_WG064