Fungicide modes of action for field crops Dr. Mary Burrows Montana State University Plant Sciences and Plant Pathology Department
What do I need to do BEFORE deciding a fungicide application is necessary?
Schutter Diagnostic Lab Identify plant diseases, insects, weeds/plants, mushrooms, toxic molds, etc. Provide management recommendations Education and outreach on plant pests Process approximately 2000 samples/yr (~50% homeowner/horticulture) http://diagnostics.montana.edu
Mobile phone platform for fluorescence imaging of nanoparticles and stretched ssdna J. Contreras-Naranjo et al. 2016. IEEE J. Sel. Topics in Quantum Electronics. v. 22.
Sign up for a FREE account to receive sugarcane aphid alerts and notifications when it has been detected near you! Visit https://www.myfields.info/sca to learn more! c. Wendy Johnson, KSU
Fungicides What is a fungicide and how does it work (conventional and organic options)? What does MOA mean? Fungicide resistance What products are available and how do I find them? Economics of fungicide use
Fungicide classes Number of classes of common pesticides for field crops Herbicide = ~16 classes Insecticide = ~17 classes Fungicide = 4-6 classes
Fungicide systemicity Non-systemic Systemic Do not penetrate into plant Redistribute on plant surfaces Multi-site inhibitors Kills spores/inhibits germination Protectant only Broad spectrum Penetrate into plant Redistribute on & within plants Single-site inhibitors Inhibits spore germination and or mycelial growth Protectant and curative Selective
Non-systemic/Multi-Site Single Site v. Multi-site Systemic v. non-systemic Systemic/Single Site Protectant only Can wash off Shorter application intervals Broad spectrum Low Risk of Resistance Protectant and curative Less prone to washing off Longer application intervals Selective High Risk of Resistance
Specific fungicides target different sites and biochemical processes Cell membrane DMI triazole fungicides General cell constituents chlorothalonil Microtubules thiophanate methyl Nucleic acids Mefenoxam and metalaxyl Mitochondria QoI (azoxy-, pyraclo-, trifloxy-, fluoxa-) SDHI (fluxapyroxad, boscalid) Cell wall Modified from Rick Latin
Contact Strobilurins Triazoles Carboxamides Common names Bravo, Thiram, Copper, Sulfur, oils Stamina, Headline, Quadris Tilt, Folicur, Proline Vibrance, Boscalid, Xemium (Priaxor) Mode of action FRAC group M: Multiple sites of action FRAC group 11: QoI (quinone outside) inhibitors (respiration); spore germination, penetration, and mycelial growth FRAC group 3 : DMI (demethylation) inhibitors; biosynthesis of sterols in fungal cell membrane; spore penetration and mycelial growth FRAC group 7: SDHI (succinate dehydrogenase inhibition; Respiration; aka carboxamides) new 2 nd generation SDHIs Residual Low Depends on the specific product; 10-30 days Resistance development Low High (specific MOA) Mobility in plant None Translaminar and systemic Protection Contact only Protective only (kill germinating spores) Medium High systemic activity Protective and curative High; Practice good resistance mgmt tactics Carboxamide not systemic (targets later-season applications) Protective Senescence Delayed Note: these are generalizations about Potentially fungicide delayed classes
Triazoles Medium Risk Strobilurins High Risk Group M (contact fungicides) Low Risk SDHI inhibitors High Risk
Spore germination Penetration Mycelial growth Germ tube formation Sporulation Carboxamides Strobilurins Triazoles (SDHIs) (QoIs) (DMIs) Fungicide efficacy No efficacy Disease symptoms
Fungicide movement in the plant From: Tenuta, A., D. Hershman, M. Draper and A. Dorrence. 2007. Using foliar fungicides to manage soybean rust.. Land-Grant Universities Cooperating NCERA-208 and OMAF. Available online at http://www.oardc.ohiostate.edu/soyrust/
Fungicide modes of action: Strobilurins FRAC group 11 QoI (quinone outside) inhibitors (respiration); spore germination, penetration, and mycelial growth Provides 14-21 days of protection High risk of resistance development because it has a very specific mode of action (they block electron transfer at the site of quinol oxidation (the Qo site) in the cytochrome bc 1 complex, thus preventing ATP formation) Originally isolated from wood-rotting fungi Strobilurus tenacellus Reduced-risk pesticide (pose less risk to human health than other chemical options at the time of registration by EPA) Control a wide array of fungal diseases Excellent preventative fungicides, but limited curative effects Plant health benefit independent of disease control?
Figure 1. Mobility of trifloxystrobin, an example of a QoI fungicide. http://www.apsnet.org/education/advancedplantpath/topics /Strobilurin/top.htm
http://archives.eppo.int/meetings/2010_conferences/septoria/06_leadbeater.pdf
http://archives.eppo.int/meetings/2010_conferences/septoria/06_leadbeater.pdf
Compare sprayed and unsprayed plots
Control (no fungicide), 14 daa
Strobilurin fungicides, 14 daa Headline Gem 500 SC
Strobiliurin + Trizole, 14 daa Quilt Quilt Xcel
Strobiliurin + Trizole, 14 daa Twinline Prosaro
Trizole fungicides, 14 daa Alto Caramba Proline
Fungicide resistance development Fungal spore with mutation that confers RESISTANCE to fungicide MOA Fungal spore susceptible to fungicide MOA
Fungicide resistance development Fungal spore with mutation that confers RESISTANCE to fungicide MOA Fungal spore susceptible to fungicide MOA When a fungal population is predominately RESISTANT to a fungicide MOA, chemical failures may occur
Biological and OMRI approved fungicides in pulses, 2016 Trade name Active ingredient Mfr. Phosphorous acid, mono- and dibasic sodium, potassium, Nufarm Agricultural ALUDE FUNGICIDE and ammonium salts Products BADGE SC Copper hydroxide; Copper oxychloride Isagro USA, Inc. CONFINE EXTRA Phosphorous acid, mono- and dipotassium salts Winfield Solutions KALIGREEN FUNGICIDE Potassium Bicarbonate Otsuka Chemical Co. KOCIDE 3000 Copper hydroxide DuPont KUMULUS DF Sulfur Arysta OXIDATE 2.0 Hydrogen dioxide; Peroxyacetic Acid BioSafe Systems REGALIA (CAUTION) Extract of Reynoutria sachalinensis Marrone Bio Innovations ACTINOVATE Streptomyces lydicus WYEC 108 Natural Industries, Inc. ROOTSHIELD GRANULES Trichoderma harzianum Rifai strain KRL-AG2 BioWorks, Inc. BIO-TAM Trichoderma asperellum (ICC 012); Trichoderma gamsii (ICC 080) AgraQuest, Inc. ROOTSHIELD PLUS WP Trichoderma harzianum Rifai strain T-22; Trichoderma virens strain G-41 BioWorks, Inc. SERENADE ASO Bacillus subtilis strain QST 713 AgraQuest, Inc./Bayer SONATA FUNGICIDE Bacillus pumilus strain QST 2808 Bayer CDMS.net
Organic fungicides https://www.extension.purdue.edu/extmedia/bp/bp-69-w.pdf
Sulfur Ancient Greeks used against rust disease Powdery mildew Prevents fungal spores from germinating Sulfur + oil (within a month) = phytotoxic Lime-sulfur is a dormant spray, more effective at lower doses but smells bad
Copper Efficacy against fungi and bacteria Copper sulfate + lime = Bordeaux mixture (safener, reduces phytotoxicity) Can persist through rain More phytotoxic at high temperatures >85F and if rain occurs very soon after application Copper especially phytotoxic on young tissue
Horticultural and neem oils Mostly used for insects Can minimize virus spread by piercingsucking insects Can help control thrips and spread of associated viruses (INSV, TSWV ) Can be used to manage powdery mildew Check phytotoxicity on plants before widespread application Do not apply <40F or >90F; best if RH <65% so oil can evaporate quickly and reduce phytotoxicity
Bicarbonates Baking soda = sodium bicarbonate Can be effective when used with oil Sodium can build up in soil and become toxic to plants Different bicarbonate salts have different effects on plants and diseases Ammonium and potassium bicarbonate preferred because of added nutrients to plants and lack of sodium
Biocontrols http://www.apsnet.org/edcenter/advanced/topics/pages/biologicalcontrol.aspx
Biological and OMRI approved fungicides in pulses, 2016 (from CDMS) Trade name Active ingredient Mfr. Phosphorous acid, mono- and dibasic sodium, potassium, Nufarm Agricultural ALUDE FUNGICIDE and ammonium salts Products BADGE SC Copper hydroxide; Copper oxychloride Isagro USA, Inc. CONFINE EXTRA Phosphorous acid, mono- and dipotassium salts Winfield Solutions KALIGREEN FUNGICIDE Potassium Bicarbonate Otsuka Chemical Co. KOCIDE 3000 Copper hydroxide DuPont KUMULUS DF Sulfur Arysta OXIDATE 2.0 Hydrogen dioxide; Peroxyacetic Acid BioSafe Systems REGALIA (CAUTION) Extract of Reynoutria sachalinensis Marrone Bio Innovations ACTINOVATE Streptomyces lydicus WYEC 108 Natural Industries, Inc. ROOTSHIELD GRANULES Trichoderma harzianum Rifai strain KRL-AG2 BioWorks, Inc. BIO-TAM Trichoderma asperellum (ICC 012); Trichoderma gamsii (ICC 080) AgraQuest, Inc. ROOTSHIELD PLUS WP Trichoderma harzianum Rifai strain T-22; Trichoderma virens strain G-41 BioWorks, Inc. SERENADE ASO Bacillus subtilis strain QST 713 AgraQuest, Inc./Bayer SONATA FUNGICIDE Bacillus pumilus strain QST 2808 Bayer CDMS.net
c. R. Sisco, UC-Davis WRIR4
45 products for wheat 20 Apr, 2016
MSU fungicide trials in dryland WW 2007-2013 35 trials 4 reps/trial, all harvested with a research combine One location, one year there was a statistically significant increase in yield with the use of a fungicide on dryland wheat in the absence of disease
Fungicide use in winter wheat NO/minimal disease, 2007-2013 Number of observations (plots) Number of observations (plots) Avg. Yield (Bu/A) Avg. Yield Bozeman (Bu/A) Havre 2007 15 97.2 2011 32 60.1 2011 28 26.0 2012 60 61.5 2012 200 45.2 2013 60 98.1 2013 66 31.1 Average 152 75.7 Average 309 43.0 Hill Co. (Kremlin) Conrad 2012 60 64.7 2011 24 75.9 2012 60 83.4 Chouteau Co (Loma) Average 84 81.3 2012 104 44.1 Moccassin 2013 72 36.4 Total 781 54.7
25 20 15 10 5 0-5 -10-15 -20 Difference in yield from the control due to fungicide (Bu/A) Overall, a 37% chance you will get 2 Bu/A yield increase due to fungicide 2 Bu/A Difference in yield (Bu/A) due to fungicide application as compared to the control
Fungicide use in winter wheat NO/minimal disease Tillering Flag Flowering Number of observations (plots) Avg yield compared to the control (Bu/A) Strobilurin 96 0.59 Triazole 76 0.12 SDHI 8 0.14 Blend 232 0.37 Average 412 0.37 Strobilurin 66 0.18 Triazole 83 1.32 Blend 176 0.55 Average 325 0.67 Blend 5 0.32 Average 5 0.32 Multiple Strobilurin 12 1.60 Blend 27 0.53 Average 39 0.86 Total 781 0.52
Fungicide use in winter wheat NO/minimal disease Number of observations (plots) Avg yield compared to the control (Bu/A) Tillering Full 185 1.18 Half 223-0.29 Quarter 4-0.61 Average 412 0.37 Flag Full 278 0.91 Half 47-0.70 Average 325 0.67 Flowering Full 5-0.32 Average 5-0.32 Multiple Full 15 1.18 Half 24 0.66 Average 39 0.86 Total 781 0.52
https://www.msuextension.org/econtools/ fungicide/index.html
Fungicide 1 Fungicide 2 What do you notice to be skeptical Fungicide 3 about? Stats? How many treatments total? Location?