Transcript Plant Disease Management

Plant Disease Management
Uses an Integrated Approach
• Exclusion
• Plant resistance
• Cultural controls
• Chemicals
• Microbiologicals
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Integrated Plant Disease Management
Exclusion
• Regulation of plant material at ports, city,
county, state or country boundaries – federal
and state rules
• Pathogen-free seed or plants
• Seed certification
• Meristem culture
• Cuttings from clean “mother” plant
under sterile conditions
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Integrated Plant Disease Management
Exclusion
Don’t Pack a Pest
http://www.dontpackapest.com
https://www.youtube.com/watch?feature=player_embedded&v=x0S99cwnDqM
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Integrated Plant Disease Management
Exclusion
Where did all the impatiens go?
Downy Mildew caused by Plasmopara obducens on Impatiens walleriana
https://edis.ifas.ufl.edu/pp309
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Integrated Plant Disease Management
Plant Resistance
Genetic
• Immunity is the rule in the plant kingdom
• If immunity does not exist, plant breeders develop
cultivars with resistance to specific pathogens
• Constitutive and inducible defenses
Chemically or Biologically Induced
• Application of chemicals or biologicals to induce
production of defense compounds
Adaptation
• Plant adaptation to site
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Integrated Plant Disease Management
Plant Resistance
Genetic
• Graft susceptible top onto resistant root stock
•http://content.ces.ncsu.edu/grafting-for-disease-resistance-in-heirloom-tomatoes
•http://edis.ifas.ufl.edu/ep339: For Florida, roses grafted on 'Fortuniana' rootstock thrive
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Integrated Plant Disease Management
Plant Resistance
Genetic
• Constitutive: continuous defenses; includes
cell walls, waxy epidermal cuticles, bark, leaf
hairs – physical and chemical barriers
• Inducible: defenses (chemicals or proteins)
produced in response to invading pathogens;
includes toxic chemicals, pathogen-degrading
enzymes, deliberate plant cell suicide
http://www.apsnet.org/edcenter/intropp/topics/Pages/OverviewOfPlantDiseases.aspx
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Integrated Plant Disease Management
Plant Resistance
Genetic
 Systemic Acquired Resistance (SAR)
• Activated when pathogen infects tissue
• Long-lasting systemic immunity, even in
tissues not infected
• Relatively broad spectrum
• Usually associated with increase in
phytohormone salicylic acid (SA)
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Integrated Plant Disease Management
Plant Resistance
Chemically Induced
Systemic Acquired Resistance (SAR)
• Use of SA or SA analogs can induce
SAR-like responses
• Provides resistance in plant tissues
beyond application site (systemic)
• Often referred to as “plant activators”
• Benzothiadiazoles (ex: Actigard) used
for plant protection
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4306307/pdf/fpls-05-00804.pdf
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Integrated Plant Disease Management
Plant Resistance
Biologically Induced
 Systemic Acquired Resistance SAR)
• Weak viruses
 Induced Systemic Resistance (ISR)
• Triggered by non-pathogenic plant growth
promoting rhizobacteria
• Involves jasmonic acid and ethylene, rather
than salicylic acid
doi: 10.1105/tpc.113.111658. Plant Cell May 2013 vol. 25, no. 5, pp. 1489–1505
doi: 10.1128/AEM.71.9.4951-4959. Appl. Environ. Microbiol. Sept. 2005 vol. 71, no. 9, pp. 4951-4959
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Integrated Plant Disease Management
Plant Resistance
Adaptation
“Right Plant for the Right Site”
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temperate vs. tropical; cold induction
dry vs. rainy
soil type: sand vs. clay
day length
others?
Genetic resistance can be overcome if
site is not right for the plant species
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Integrated Plant Disease Management
Cultural Controls
• Crop rotation
• Alternate host eradication – for pathogens
and vectors
• Sanitation of tools, equipment, potting
containers, shoes, etc.
• Improved plant environment, especially water
management, air circulation
• Nutrient management
• Soil treatment, such as solarization, tillage
• Mulches or other barriers
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Integrated Plant Disease Management
Chemical Controls
Fungicides
Bactericides
Nematicides
Insecticides
Fumigants
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Seed treatments
Soil treatments
Root drenches
Disinfecting tools
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Foliar sprays
Trunk injections
Trunk sprays
Post-harvest use
For fungicides and bactericides, the “cides” is not
accurate. Most suppress rather than kill.
There are no chemicals to use against plant viruses.
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Integrated Plant Disease Management
Chemical Controls
Figure 1. U.S. Crop Protection Fungicide Use
From: http://www.apsnet.org/publications/apsnetfeatures/Pages/Fungicides.aspx
Also see: http://www.apsnet.org/edcenter/intropp/topics/Pages/Fungicides.aspx
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Integrated Plant Disease Management
Chemical Controls
Year
Fungicide
Primary Use
1637
Brine (Salt)
Cereal seed treatment
1755
Arsenic
Cereal seed treatment
1760
Copper sulfate
Cereal seed treatment
1824
Sulfur (dust)
Powdery mildew and other pathogens
1833
Lime sulfur
Broad spectrum foliar pathogens
1885
Bordeaux mixture
Broad spectrum foliar pathogens
1891
Mercury chloride
Turf fungicide
1900
CuOCl2
Especially Phytophthora infestans
1914
Phenylmercury chloride
Cereal seed treatment
1932
Cu2O
Seed and broad spectrum foliar diseases
1934 Dithiocarbamates patented
Broad spectrum protectants
1940
Chloranil, Dichlone
Broad spectrum seed treatment
From: http://www.apsnet.org/publications/apsnetfeatures/Pages/Fungicides.aspx
(IN)Organic Fungicides: https://www.extension.purdue.edu/extmedia/bp/bp-69-w.pdf
Organic Materials Review Institute: http://www.omri.org/
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Integrated Plant Disease Management
Chemical Controls
Mode of action of some major fungicides classes, their FRAC code and resistance risk
FRAC
Code
1
Resistance
Mode of action / inhibition
risk
Beta-tubulin assembly in mitosis (cytoskeleton and motor proteins)
high
Chemical Class
Benzimidazoles
2
Dicarboximides
MAP/Histidine-kinase in osmotic signal transduction
medium-high
3
Azoles, Pyrimidines
C-14 demethylation in sterol biosynthesis in membranes
medium
4
5
7
9
Phenylamides
Morpholines
Carboxamides
Anilinopyrimidine
RNA polymerase I (nucleic acid synthesis)
^8 and ^7 isomerase and ^14 reductase in sterol biosynthesis
Succinic acid oxidation (respiration)
Methionine biosynthesis (amino acid and protein synthesis)
high
low-medium
medium
medium
11
Strobilurins
Mitochondrial synthesis in cytochrome bc1 (respiration)
high
16
Various chemistry
Melanin biosynthesis (two sites) in cell wall
medium
40
Carboxylic acid amides
Cellulose synthase (cell wall formation in Oomycetes)
low-medium
M1
M3
Inorganics
Dithiocarbamates
Multisite contact
Multisite contact
low
low
M5
Phthalimides
Multisite contact
low
Fungicide Resistance Action Committee: http://www.frac.info; http://edis.ifas.ufl.edu/pi131
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Integrated Plant Disease Management
Chemical Controls
From:
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Integrated Plant Disease Management
Microbiological Controls
 Fungi:
Trichoderma, Candida, Muscodor, Pythium, Ulocladium,
Verticillium
 Bacteria:
Bacillus group, Streptomyces, Xanthomonas,
Pseudomonas, Pantoea, Pasteuria, Agrobacterium, Paecilomyces,
Burkholdaria
http://www.apsnet.org/edcenter/advanced/topics/Pages/BiologicalControl.aspx
https://www.epa.gov/pesticides/biopesticides
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Integrated Plant Disease Management
Microbiological Controls
 Effective because they produce:
• Antibiotics
• Lytic enzymes
• Biocidal volatiles
• Detoxification enzymes
• Iron-chelating siderophores
 Effective because they outcompete the
pathogens
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Integrated Plant Disease Management
Microbiological Controls
Bacillus subtilis strains:
•QST 713
•MBI 600
•GB03
•FZB24
Registered by EPA as biopesticide
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Plant Disease Management
Uses an Integrated Approach
• Exclusion
• Plant resistance
• Cultural controls
• Chemicals
• Microbiologicals
University of Florida - IFAS
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Integrated Plant Disease Management
GMOs
Is there a place for
GMOs in our integrated
plant disease
management tool box?
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Integrated Plant Disease Management
GMOs
Some diseases cannot be
controlled with any currently
available methods!
Florida Example:
Bacterial Spot Disease of Tomatoes
The Good, the Bad, and the Ugly: What the Future Could Hold for Bs2 Tomatoes
http://edis.ifas.ufl.edu/hs1259
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