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Dr. George Sundin - Antimicrobial Use in Plant Agriculture
 

Dr. George Sundin - Antimicrobial Use in Plant Agriculture

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Antimicrobial Use in Plant Agriculture - Dr. George Sundin, Michigan State University, from the 2012 NIAA One Health Approach to Antimicrobial Resistance and Use Symposium, October 26-27, 2012, ...

Antimicrobial Use in Plant Agriculture - Dr. George Sundin, Michigan State University, from the 2012 NIAA One Health Approach to Antimicrobial Resistance and Use Symposium, October 26-27, 2012, Columbus, OH, USA.

More presentations at:
http://www.trufflemedia.com/agmedia/conference/2012-one-health-to-approach-antimicrobial-resistance-and-use

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  • Show structures of both strep and kasug
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Dr. George Sundin - Antimicrobial Use in Plant Agriculture Dr. George Sundin - Antimicrobial Use in Plant Agriculture Presentation Transcript

  • Antimicrobial Use in Plant Agriculture George W. Sundin NIAA Sympsium;November 13, 2012
  • Bacterial Plant Diseases• Occur on most crop plants, fruits, vegetables etc.• Major effects of diseases are spots and rots on fruit or lesions on leaves that lead to reductions in yield• Wilting diseases can kill plants
  • Citrus canker Bacterial spot on pepper
  • Pseudomonas syringae– bacterial brown spot of bean
  • Symptoms Soft rot
  • Bacterial Diseases are Exceedingly Difficult to Control• Bacterial disease is a population-driven process• Large populations can develop on plant surfaces under optimal environmental conditions – 105 to 106cfu/g on leaves – As high as 1011cfu/g in xylem• Copper bactericides – Rapid re-establishment of populations after control treatment – Other control agents needed
  • Bacterial Diseases are Exceedingly Difficult to Control• Lack of host resistance is a critical issue• Most popular varieties are typically the most disease susceptible ‘Gala’ ‘Golden Delicious
  • Streptomycin• Discovered by Selman Waksman in 1943• Activity against gram-negative and gram-positive bacteria
  • Antibiotics examined for plant disease control (1940s)• Penicillin• Streptomycin• Aureomycin• Chloramphenicol• Oxytetracycline
  • Problems with antibiotic use for plant disease control (1940s-50s)• Lack of efficacy at lower doses• Phytotoxicity issues at higher doses• Expense compared to other existing methods of disease control
  • Streptomycin• Utilized in plant disease management since the early 1950’s• 100 ppm solution – Targets: – Fire blight of apple and pear – Bacterial blight of celery – Shoot tip dieback of nursery trees – Bacterial spot of tomato and pepper
  • Streptomycin Usage on Apples in the USA Streptomycin usage (1,000s of pounds) 25 20 15 10 5 0 1991 1993 1995 1997 1999 2001 2003
  • Streptomycin Usage on Plants• Avg. 20,200 lbs streptomycin/yr on apple• 1991-2003 data USDA NASS• Treated acreage -- ~ 15%(1-3 applications)• Avg. 10,000 lbs streptomycin/yr on pears• Treated acreage -- ~ 37%(1-3 applications)
  • Antibiotic Usage on Plants• Total annual usage on plants -- ~ 20,000 kg to 65,000 kg (1990s data)• Lower estimate from NASS• Higher estimate from US Geological Survey• By either estimate, plant use is less than 0.5% of 22.6 million kg of annual US production of antibiotics
  • Fire Blight Disease • Reduces fruit yields • Kills branches • Kills roots (tree death)
  • 2000 Fire Blight Epidemic, Southwest Michigan• Tree losses -- approximately 450,000 trees killed• Acreage -- approximately 2,300 acres lost in five counties• 35% overall yield reduction statewide
  • Fire blight: match between a plantdisease system and an antibiotic for control• High economic value crop• Focused time frame of use – Need is during bloom (~ 2-3 weeks) – Significant population reduction necessary for disease control on flowers• System amenable to use of streptomycin• Development of disease forecasting/warning systems
  • stigmaca. 105 to 106 cells / stigma
  • stigmaca. 105 to 106 cells / stigma
  • Blossom blight infection
  • Management of Blossom Blight with Streptomycin 90 80 70 60 50 40 30 20 10 0 Trial data, East Lansing, MI
  • Use of streptomycin for fire blight management• Highly effective control measure for blossom blight in affected states:• West, PNW – CA, OR, WA• Midwest – MI, WI, IN, OH• East – NY, PA, VA, MA• 1-3 applications of streptomycin @ 100 ppm during bloom
  • Problem: shoot blight could occur on highly-susceptible apple cultivars throughout the growing season
  • Problem: shoot blight could occur on highly-susceptible apple cultivars throughout the growing season Solution: increase applications ofstreptomycin to control shoot blight
  • Streptomycin Resistance in E. amylovora in Michigan• Early-mid 1990’s -- Southwest Michigan• 2004 -- Fruit Ridge area• 2005 -- Fruit Ridge area (further spread), Ionia cty.• 2006 -- Oceana county• 2010 – Grand Traverse county• 2012 – Leelanau, Antrim counties
  • Oxytetracycline• Structure identified by Robert Woodward in 1953• Produced by Streptomyces rimosus• Medical uses, animal husbandry, plant pathology• Bacteriostatic
  • Oxytetracycline• Degradation by sunlight:
  • Oxytetracycline Usage on Plants in the USA Oxytetracycline usage (1,000s of pounds) 30 25 20 15 10 5 0 1991 1993 1995 1997 1999 2001 2003Oxytc: more use on peaches (bacterial spot) than on apples and pears
  • Oxytetracycline and Blossom Blight Control Under Higher Pressure 80% Blossom Blight 70 60 50 40 30 20 10 0 Agrimycin Oxytetracycline Control
  • Kasugamycin• Kasugamycin – aminoglycoside antibiotic in the same class as streptomycin• Produced by Streptomyces kasugaensis• Targets the bacterial ribosome – target site is different from that of streptomycin• No cross resistance between streptomycin and kasugamycin• No medical uses, no animal agriculture
  • Evaluation of Kasumin for fire blightcontrol in East Lansing, MI field trials70 Streptomycin Kasumin Nontreated control605040302010 0 2006 -- 2007 – 2007 – 2008 – 2008 – 2009 – Gala Jonathan Jonathan Gala Jonathan Jonathan #1 #2
  • Kasugamycin• Kasumin – use in Michigan through a Section 18 specific exemption from the EPA (2009-2011)• Label requirements: – Can only be used in counties where streptomycin resistance has been reported – Can only be used when fire blight disease model predicts epidemic conditions – Can only be used during bloom – No more than two consecutive applications, three maximum
  • Non-antibiotic methods of plant disease control• Plant disease resistance• Copper spray materials – Cu(OH)2; CuSO4• Biological controls – Antagonistic bacteria; Bacteriophage; Antimicrobial peptides• Plant growth regulators• Plant resistance inducers
  • Summary – Antibiotic use in plant agriculture• Streptomycin, oxytetracycline, kasugamycin• Targets are diseases on high-value crops• The nature of bacterial plant diseases and the economic necessity of growing highly disease- susceptible cultivars contributes to antibiotic use• Use of disease forecasting systems helps to limit the number of antibiotic applications• Growers are more aware of resistance management strategies and of not overusing antibiotics
  • Funding sources:USDA – NIFAUSDA -- SCRIMSU Project GREEENMI Apple Committee