2009-10 Bentgrass Samples By Month 2009 2010120906030 0 n b ar r ay n l g p ct ov c Ju Ap De Ja Ju Au Fe Se O M M N
Who developed your fungicide program?Manufacturer or Distributor University Researcher Colleague I developed it. I don’t know. 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
How often do you make changes to your program duringthe season? frequently sometimes never 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
What factors do you consider when making changes? disease outbreaks online alerts diagnostic lab resultsreports from colleaguesreports from sales reps weather conditions 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
What sources of information do you use when selecting fungicides? Manufacturer or Distributor University Personnel ColleaguesPest Control for Professional Turf Managers Disease Management Utility on TurfFiles Disease Profiles on TurfFiles product labels 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
Which of these is your primary source of information when selecting fungicides? Manufacturer or Distributor University Personnel ColleaguesPest Control for Professional Turf Managers Disease Management Utility on TurfFiles Disease Profiles on TurfFiles product labels 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
Did you have any disease outbreaks in 2010? algae anthracnose bacterial wilt brown patch copper spot dollar spot fairy ring Pythium blight Pythium root dysfunction Pythium root rot red leaf spot slime mold pink snow mold summer patch yellow patch none 0 3 6 9 12 15 # of respondents Survey conducted at NC Turf Conference, December 14 2010
History of Bacterial Diseases• severe epidemic in Midwestern US on ‘Toronto’ creeping bentgrass in 1970’s caused by Xanthomonas transluscens• X. transluscens continues to be an occasional problem on Poa annua greens in the northern US• efforts to develop this into a bio-herbicide failed due to lack of efﬁcacy in absence of severe stress• 2009 - report of a bacterial disease caused by Acidovorax spp. in Charlotte, NC
Koch’s Postulates: Establishing a Cause-EffectRelationship1. Suspected pathogen must be constantly associated with speciﬁc symptoms over time and space2. Suspected pathogen must be isolated into pure culture and identiﬁed3. Same symptoms are reproduced when suspected pathogen is introduced to healthy plants4. Suspected pathogen re-isolated from symptomatic plants and identiﬁed
Bacterial Disease TimelineJune 2009 - samples from Quail Hollow Country Club submitted toMichigan State University for disease diagnosisOctober 1, 2009 - Michigan State reported to Quail Hollow that theproblem was a bacterial disease caused by a species of AcidovoraxOctober 2, 2009 - attempted to contact Dr. Vargas for informationMay 19, 2010 - received response from Paul Giordano:
Communication from MSU on May 19, 2010....we believe the bacterium is the causal organism, or at least partiallyresponsible for the issue........we are still in the beginning stages of investigating this problem, andwould like to have sound scientiﬁc evidence supporting our conclusionsbefore giving any concrete answers........we would like to initiate some collaborative research with your labaimed at positive identiﬁcation of the problem....
Plant Disease Note,Published June 2009• ...a golf course putting green sample...• ...symptoms of general wilt, decline, and characteristic necrosis...• ...bacterial streaming was present in all of the infected tissue...• ...3 different bacteria were isolated...• ...one resulted in slight browning of leaf tips just 2 days after inoculation...
Plant Disease Note,Published July 2009• ...when leaf tips of the inoculated plants were cut, bacterial streaming was observed...• ...DNA sequencing results indicated that the causal agent was a member of the Acidovorax genus...• ...this is the ﬁrst report of a bacterial disease affecting creeping bentgrass caused by Acidovorax spp. in the US.
USGA Survey Results• 51 people participated in the survey RI• 30 suspected they had bacterial wilt on Rutgers their greens MSU• 25 submitted samples to a laboratory for analysis Turf Diag.• 23 had laboratory conﬁrmed diagnosis of Purdue bacterial wilt on the samples NCSU• The bacterium Acidovorax was identiﬁed in 8 cases 0 3 6 9 12 15 # of samples
So now what do we do?• We need to do the work to ﬁgure it out!• What bacteria are normally associated with healthy and declining bentgrass?• Are there bacterial species consistently associated with etiolated or declining bentgrass?• Can these symptoms be reproduced through ﬁeld inoculations with these bacteria?• If any are pathogenic, can they be controlled with antibiotics or other compounds?
Scalping Chemical BurnHeat Herbicide Injury What bacteria are normally associated with dead and declining bentgrass?
Management of Bacterial DiseaseALLEVIATE STRESS! • raise mowing heights • reduce mowing frequency • mow in evening or when turf is dry • avoid abrasive practices such as aeriﬁcation or topdressing • LIGHT and FREQUENT applications of complete foliar fertilizers • irrigate in morning to prepare for heat of day, ensure that foliage dries in between syringe cycles
What are the chemical control options?• hydrogen dioxide• streptomycin sulfate• oxytetracycline• ningnamycin• others?
Improved granular technology makes foliar disease control possible
Fungicides Now Available on Granular Carriers • Disarm • Headway • Heritage • Insignia
Comparison of Granular and Sprayable Fungicides Armada G (8 lb) Armada WP (1.2 oz)Heritage WG (0.2 oz)Lawn Fungus Control Untreated 0 5 10 15 20 Brown Patch Incidence (%) Treatments applied 18 Jun, 16 Jul and 13 Aug
Comparison of Granular and Sprayable Fungicides Heritage G (3 lb) Compass G (4 lb) Disarm G (2.3 lb)Heritage WG (0.2 oz) Untreated 0 3 6 9 12 15 Brown Patch Incidence (%) Granular treatments re-applied every 21 days, Heritage 50WG re-applied every 28 days
The DMI Fungicides: A Growing Chemical Class• fenarimol (Rubigan)• metconazole (Tourney)• myclobutanil (Eagle)• propiconazole (Banner Maxx)• tebuconazole (Torque)• triadimefon (Bayleton)• triticonazole (Trinity, Triton)
Tourney (metconazole)• 0.18 to 0.37 oz application rate (0.44 oz for snow mold)• 14 to 21 day application interval• improved control of anthracnose and brown patch compared to other DMIs• less growth regulation / injury potential on cool-season grasses• not labeled for application to bermudagrass
Trinity (triticonazole)• 0.5 to 2 oz application rate• improved brown patch activity compared to older DMIs• very good control of anthracnose, fairy ring, and summer patch• safer on cool-season grasses, but not labeled for application to ultradwarf bermudagrasses
Triton FLO (triticonazole) • 0.28 to 1.1 ﬂ oz application rate • includes StressGard pigment • similar to other triticonazole formulations, but pigment can reduce negative side effects • not for application to ultradwarf bermudagrasses
Torque (tebuconazole) • 0.6 ﬂ oz application rate • golf course use only • Don’t exceed 3.6 ﬂ oz total/year • not recommended for ultradwarf putting greens • great for SDS & fairy ring
DMI Fungicides: Issues to Consider• phytotoxicity• leaf texture• reduced density• slowed recovery• interactions with growth regulators• bentgrass vs. bermudagrass
DMI Injury is Rate, Interval, and Timing Dependent Heritage (0.4 oz, 28 d) Triton (2 oz, 14 d)
Even a single application can cause signiﬁcant turf injury.
DMI Phytotoxicity on Creeping Bentgrass Bayleton (1.5 fl oz, 2 apps) Tartan (2 fl oz, 2 apps) Tourney (0.37 oz, 4 apps) Banner Maxx (2 fl oz, 4 apps) Untreated 0 1.5 3.0 4.5 6.0 Phytotoxicity (0 to 9) Treatments applied in March and April; data collected on July 10
Are the DMIs safe on bermudagrass greens? Bayleton (1 fl oz) Banner Maxx (2 fl oz) Tourney (0.37 oz) Trinity (2 fl oz) Triton FLO (1 fl oz) Untreated 0 1 2 3 4 5 Phytotoxicity (0 to 5) Treatments applied Aug 20; data collected Sept 1
Are the DMIs safe on bermudagrass greens? Bayleton (1 fl oz) Banner Maxx (2 fl oz) Tourney (0.37 oz) Trinity (2 fl oz) Triton FLO (1 fl oz) Untreated 0 10 20 30 40 50 60 70 80 90 100 Recovery (# of aerification holes visible) Treatments applied Aug 20; data collected Sept 1
Be careful when mixing DMIs and PGRs Trinity (1 fl oz) Trinity + Cutless (1 fl oz + 4 oz/A) Trinity + Cutless (1 fl oz + 8 oz/A)Trinity ALT Cutless (1 fl oz ALT 4 oz/A) Untreated 0 1 2 3 4 5 Phytotoxicity (0 to 5)
DMI-PGR Combinations on Creeping Bentgrass• applications initiated on June 10, 2009• DMIs applied every 28 days at highest rate recommended for foliar diseases• PGRs applied every 14 days at typical rates June 17, 2009
DMI-PGR Combinations on Creeping Bentgrass• growth regulators alone caused more injury than fungicides alone• DMI-PGR programs can cause increased phytotoxicity when compared to either applied alone• Triton FLO caused the least phytotoxicity and actually increased turf quality over time• Cutless and Legacy caused more phytotoxicity than Primo Maxx• negative side effects reduced over time with continued use