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Persistence of Metarhizium anisopliae

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Persistence of Metarhizium anisopliae

  1. 1. ESA ANNUAL MEETING 2009 Persistence of Metarhizium anisopliae conidia applied beneath a cover crop canopy for sugarbeet root maggot management Ayanava Majumdar, Ext. Specialist, Auburn University, AL Mark A. Boetel, Assoc. Prof., North Dakota State University Stefan T. Jaronski, USDA-ARS NPARL, Sidney, MT
  2. 2. <ul><li>Tetanops myopaeformis (Diptera: Ulidiidae):10 to100% yield loss (Cooke 1993) </li></ul>10x Research component 1 (SBRM)
  3. 3. Research component 2 (cereal cover crops) Cover crops + terbufos reduced root injury (Dregseth et al. 2003) Oat 186 seeds/m 2 Rye 186 seeds/m 2 Oat 374 seeds/m 2 Rye 374 seeds/m 2 seeds/m 2 Non-cover sugarbeet plot
  4. 4. Research component 3 ( M. anisopliae F52) Pure culture of F52 Granular formulation (on corn meal carrier) Infected SBRM larva USDA-ARS scientists demonstrated efficacy of F52 against SBRM larvae (Jonason et al. 2005, Campbell et al. 2006) In this study: F52 rate 8 x 10 12 viable conidia/ha, as soil incorporated granule or spray at the base of plants
  5. 5. Years: 2002-2004 Location: Pembina Co. Split-plot design Main plot: seeding rates (0, 186, 374 seeds/m 2 ) Sub plot: biocontrol formulations FIELD SAMPLING 4 samples per plot Sampling time: 0 and 30 or 60 days after tret. Stainless steel core sampler Sampler disinfected between each sample Samples transported under cool conditions Persistence study methodology LABORATORY PROCESSING Serial dilution with 1 g soil sample (Goetel & Inglis 1997) 100 micro L plated on modified Chase medium, replications = 4 Colony forming units (CFUs) counted at 10 days 2 g subsample for soil moisture estimation >> CFUs adjusted Plates were scanned
  6. 6. <ul><li>Mean CFU counts were subjected to Analysis of Variance </li></ul><ul><li>Folded F-test: to determine feasibility of combined analysis </li></ul><ul><li>Treatment means from significant interaction terms were analyzed by using LSD at P = 0.05 </li></ul>Data analyses
  7. 7. PROC ANOVA: 2002 & 2003 conidial persistence 2002 2003 Source df Mean square F P Mean square F P Replication 3 1051.809 0.95 0.4286 219.123 1.38 0.2693 Cover type 4 884.037 0.74 0.5850 159.059 1.24 0.3474 Error (a) (Replication x Cover type) 12 1201.300 - - 128.788 - - Formulation 1 58639.035 45.41 <0.0001 5824.284 45.93 <0.0001 Cover type x Formulation 4 1045.222 0.81 0.5383 149.918 1.18 0.3583 Error (b) (Replication x Cover type x Formulation) 15 1291.292 - - 126.811 - - Sampling date 1 42610.296 31.87 0.0110 4360.104 17.25 0.0254 Error (c) (Replication x Sampling date) 3 1337.127 - - 252.688 - - Cover type x Sampling date 4 1118.789 1.01 0.4174 132.279 0.83 0.5150 Formulation x Sampling date 1 58379.415 52.94 <0.0001 3931.208 24.81 <0.0001 Cover type x Formulation x Sampling date 4 773.560 0.70 0.5977 129.339 0.82 0.5260 Error (d) 27 1102.7245 - - 158.462 - - Combined analysis not possible. Formulation and sampling date had significant effect on conidial persistence. Conidial counts were averaged formulation X sampling date
  8. 8. 2002 results: F52 Formulation X Sampling date 610 ± 544 a 11428 ± 652 b 1409 ± 897 a 1397 ± 1283 a Observation: Choosing formulation/delivery system is critical to conidial persistence Finding: Granular formulation may be benefited by soil microenvironment
  9. 9. 2003 results: F52 Formulation X Sampling date 80 ± 136 a 6 ± 27 a Observation: Detecting conidia in soil is difficult (dilution effect) Finding: Spray form lost 90% conidia in 30 days (2 yr) 3189 ± 2413 b 310 ± 411 a
  10. 10. PROC ANOVA: 2004 conidial persistence Source df Mean square F P Replication 3 16791.945 1.39 0.2682 Cover type 1 83.364 0.01 0.9152 Error (a) (Replication x Cover type) 3 6226.715 - - Seeding rate 2 4552.400 0.35 0.7169 Cover type x Seeding rate 1 7070.494 0.54 0.4826 Error (b) (Replication x Cover type x Seeding rate) 9 13180.971 - - Formulation 1 1387151.420 145.50 <0.0001 Cover type x Formulation 1 573.018 0.06 0.8097 Seeding rate x Formulation 2 3449.191 0.36 0.7023 Cover type x Seeding rate x Formulation 1 3990.279 0.42 0.5274 Error (c) (Replication x Cover type x Seeding rate x Formulation) 15 11073.077 - - Sampling date 1 1093204.911 70.67 0.0035 Error (d) (Replication x Sampling date) 3 15468.986 - - Cover type x Sampling date 1 1545.637 0.13 0.7235 Seeding rate x Sampling date 2 3509.930 0.29 0.7503 Formulation x Sampling date 1 1222780.369 101.18 <0.0001 Error (e) 26 12085.752 - - Formulation and sampling date had significant effect on conidial persistence. Conidial counts were averaged formulation X sampling date and…
  11. 11. 2004 results: F52 Formulation X Sampling date Observation: High variability in conidial detection between years Finding: Spray form lost >90% conidia in 30 days (3 yr)
  12. 12. Cover crop microenvironment 30 day conidial degradation rates: Oat + Granule = 81% (2 year av.) Rye + Granule = 78% (2 year av.) Oat + Spray = 88% (3 year av.) Rye + Spray = 92% (3 year av.) Microclimate under cover crops (May-July): What was going on in the cover crop microenvironment? WatchDog 425 & Watermark sensor Degradation rates Soil Temp. (C) Water tension (kPa) Low rate OAT G: 63%, S: 84% 18 23 High rate OAT G: 100%, S: 92% 21 36 Low rate RYE G: 80%, S: 95% 19 20 High rate RYE G: 75%, S: 88% 19 25 No cover 17
  13. 13. <ul><li>Sampling time & technique are important for assessing persistence </li></ul><ul><li>Detection of conidia in disturbed soils could be difficult </li></ul><ul><li>Cover crops provide unique microenvironment under the canopy </li></ul><ul><ul><li>Lower rate of cover crop + microbial has advantages (stable microenvironment, ease of application) </li></ul></ul><ul><li>Microbial formulation/delivery technique is important for increasing persistence </li></ul><ul><ul><li>Conidia persisted 30-60 days </li></ul></ul>Overall recommendations
  14. 14. ACKNOWLEDGEMENT Research specialists: Robert Dregseth, Allen Schroeder Cooperators: Baldwin Farm (Pembina Co., ND) Statistics & data interpretation: Dr. Richard Horsley Funding agency : USDA Pest Management Alternatives Program QUESTIONS?

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