Screening and evaluation of fungicides for the control of sugarcane smut in seedcane Click here to add title

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1 Screening and evaluation of fungicides for the control of sugarcane smut in seedcane Click here to add title Shamsul A Bhuiyan Rebecca S James Barry J Croft Mike C Cox

2 Sugarcane Smut Smut is caused by the fungus Ustilago scitaminea (Sporisorium scitamineum) Infected plant produces whiplike structures (sori) The sorus has a central core of pithy tissue (modified flower) surrounded by masses of black/brown sooty spores

3 Sugarcane Smut Yield losses Susceptible varieties can be severely affected Tillers become very thin and grassy Average yield losses of 6% for every 10% infected plants Plants can die resulting in gappy ratoon crops Can cause total crop losses in susceptible variety, if infected seedcane is planted

4 Management of sugarcane smut Resistant varieties most effective Other Application of fungicides to seedcane Rouging Clean plant materials, farm equipment

5 Fungicides to manage sugarcane smut Fungicides have been used overseas to protect seedcane, particularly after hot water treatment (HWT) HWT is used to eliminate systemic infection of fungal or bacterial diseases such as smut, leaf scald, ratoon stunting or chlorotic streak

6 Fungicides to manage sugarcane smut Disadvantage of HWT is that they can soften the buds making them more susceptible to reinfection in soil contaminated with smut spores

7 Issues? Triazole fungicides, triadimefon and propiconazole have been used in South Africa and Zimbabwe against sugarcane smut These two fungicides are currently being used under emergency permit to treat seedane against sugarcane smut Efficacy of fungicides from other groups such as strobilurin, or systemic resistant inducer was unknown Metalaxyl fungicide is routinely used to protect sugarcane seedlings from Pythium root rot. Implication of this fungicide on smut is unknown

8 Objectives Initially to screen candidate fungicides for their ability to prevent spore germination in vitro To determine the efficacy of selected fungicides in the field to control sugarcane smut

9 In vitro fungicide screening Fungicide were added to water agar Smut spore suspension (1.5x10 6 spore/ml water) was streaked onto the agar Incubated for 8 h at 30 o C Assessed for spore germination

10 Fungicides on spore germination (50 to 1000 ppm) AML = Acibenzolar-s-methyl, ABN = Azoxystrobin, CPL = Cyproconazole, DAC = Didecyl dimethyl ammonium chloride, DNL = Difenoconazole, MTL = Metalaxyl, PPL = Propiconazole, QTN = Quintozene, TDN = Triadimefon

11 Fungicides on spore germination (50 to 500 ppm) CPL = Cyproconazole, ABN = Azoxystrobin, TDN = Triadimefon, AML = Acibenzolar-s-methyl, QTN = Quintozene, DAC = Didecyl dimethyl ammonium chloride, PPL = Propiconazole

12 Fungicides on spore germination (0.5 to 5 ppm) Fungicide 0 ppm 0.5 ppm 1 ppm 2.5 ppm 5 ppm Azoxystrobin 0.6 d 0.2 d 0.0 d 0.0 d Quintozene 13.5 b 0.0 d 0.0 d 0.0 d Didecyl dimethyl ammonium chloride 6.5 c 3.5 cd 0.0 d 0.0 d No fungicide control 88.5 a Lsd = 5.7 (P=0.05) 5.7

13 Field experiments Two trials were established at BSES smut research farm, Kinkuna, Bundaberg in summer 2008 and autumn 2009 One- or two-eye-setts were dipped into fungicide suspension after HWT 3 rates for each fungicide 1x, 1/2x, and 2x Then, dipped into smut spore suspension and planting in the field Assessed for incidence and severity

14 Fungicide efficacy after 6 months 2008 summer experiment Rate ml (a.i.)/100 L water Fungicide Germination Incidence Severity % Control Metalaxyl * 54.2 * Metalaxyl * 65.8 * Metalaxyl * 72.1 * Acibenzolar-s-methyl Acibenzolar-s-methyl * 42.0 * Acibenzolar-s-methyl * 26.2 Difenoconazole * 27.7 Difenoconazole Difenoconazole Azoxystrobin Azoxystrobin Azoxystrobin Triadimefon Triadimefon Triadimefon Cyproconazole Cyproconazole Cyproconazole Propiconazole Propiconazole Propiconazole Lsd (P<0.05)

15 Fungicide efficacy after 6 months 2008 summer experiment

16 Fungicide efficacy after 9 months 2009 autumn experiment Fungicide AUDPC Rate ml or g (ai) /100 L water Germination % Incidence % Severity % Metalaxyl ab 36.6 a 5231 ab Metalaxyl a 40.3 a a Metalaxyl b 30.3 a ab Control ab 33.6 a b Acibenzolar-s-methyl c 18.1 b c Difenoconazole cd 12.4 dbc cd Acibenzolar-s-methyl cd 14.3 bc cd Acibenzolar-s-methyl cde 7.9 cde cde Difenoconazole cdef 9.6 bcde cde Azoxystrobin cdef 9.6 bcde cde Azoxystrobin ef 4.6 cde de Difenoconazole def 6.4 cde de Azoxystrobin ef 2.8 de e Triadimefon ef 1.7 e 92.5 e Triadimefon f 0.0 e 0.0 e Triadimefon ef 0.3 e 39.4 e Propiconazole f 0.0 e 0.0 e Propiconazole f 0.0 e 0.0 e Propiconazole ef 0.4 e 47.9 e Cyproconazole ef 0.5 e 67.0 e Cyproconazole f 0.0 e 0.0 e Cyproconazole f 0.0 e 0.0 e LSD (P<0.05)

17 Fungicide efficacy after 9 months 2009 autumn experiment

18 In summary Triazole fungicides propiconazole, triadimefon, and cyproconazole were most effective in controlling sugarcan smut in seedcane Strobilurin fungicide azoxystrobin also effective in protecting sugarcane against smut Efficacy of fungicides last 6 to 9 months Results are reported on efficacy of fungicides to protect a highly susceptible variety (Q205) These results have great implication in protecting seedcane against sugarcane smut Obtaining full registration for two triazole fungicides, Identified new fungicides effective in controlling sugarcane smut

19 Further issues and future direction Treating sugarcane stalks in fungicides suspension has some disadvantages Dipping 1 2 tonnes of sugarcane in 5000 to L of suspension is difficult Disposing waste fungicide in environmentally safe way is difficult Research is underway to To find fungicides which are more mobile in the plant Determine an alternative method of application of fungicide against sugarcane smut

20 Thanks Vicki Barden Dennis Taylor George Bade SRDC for funding Syngenta Australia for fungicides