Exam 4 Flashcards
Prevent entry of pathogen into growing area
Exclusion
Prevent contact between pathogen and host
Avoidance/Evasion
Reduce pathogen population
Eradication
Prevent infection by means of toxicant or barrier
Protection
Increase host resistance to the pathogen
Resistance (Immunization)
Cure plants that are already infected
Therapy
6 Principles of Disease Control
Exclusion Avoidance/Evasion Eradication Protection Resistance (Immunization) Therapy
What 2 disease control principles interrupt attachment?
Protection, Avoidance
What 3 disease control principles interrupt penetration?
Avoidance, Protection, Resistance
What disease control principle interrupts infection?
Resistance
What 2 disease control principles interrupt colonization?
Resistance, Therapy
What disease control principle interrupts survival/
Eradication
What 2 disease control principles interrupt dissemination?
Exclusion, Eradication
What disease control principle interrupts inoculation?
Avoidance
What is the impact of reducing initial inoculum in a polycyclic disease?
Rate/time drive the equation so inoculum doesn’t matter (exponential)
Manipulation of the growing system
Cultural control
3 characteristics of cultural control
Create an environment less favorable to disease development
Reduce pathogen load
Prevent/inhibit spread of organisms
4 Cultural Control Tactics
Ground preparation
Seed and Planting
Irrigation Practices
Site Management
Which cultural control tactic involves tillage, bedding, mulching, cover cropping, and solarization?
Ground preparation
Which cultural control tactic involves seed selection, seed treatment, planting date?
Seed and planting
Which cultural control tactic involves type, placement, and timing?
Irrigation practices
Which cultural control tactic involves eradication of alternate hosts, biodiversity islands?
Site management
3 elements of regulatory control (pathogen exclusion)?
Quarantine
Inspection
Destruction
Careful selection of propagation material (“Pathogen-free seed”) and seed certifications are examples of…
pathogen avoidance
Crops grown when/where no other crops of the same species are planted
Crop isolation
Crop grown when and where climatic conditions favor the host more than pathogen
Crop suitable to climate
What is the goal of pathogen eradication?
Reduction of inoculum
7 methods of pathogen eradication
Sanitation Host eradication Crop rotation Irrigation and drainage Soil sterilization and solarization Propagation material treatments Vector control
Which eradication method targets infected plant material, infested soil, and laborers and tools?
Sanitation
Which host is eradicated when infected plants and volunteers are destroyed?
Primary host
In regards to host eradication, rusts are what kind of host?
Alternate
Eradicating secondary inoculum hosts and overwintering hosts are examples of what kind of hosts?
Alternative
In regards to host eradication, ______ include fields, cull piles, and manure.
Volunteers
4 concerns with host eradication
Labor
Cost
Politics
Efficacy
Why is alternating crops an effective method of disease control?
Different pathogens, airborne vs. soilborne, soil survivors vs. soil inhabitants
4 things to consider regarding irrigation
Manner
Timing
Frequency
Water Source
3 methods of drainage
Slope
Raised beds
Drainage systems
What is used for soil sterilization?
Steam, fumigant
What is used for solarization?
Field with plastic and sunlight
How is hot water used for seed treatment as a propagation method?
48-52 C, 20-30 minutes
What are 3 factors involved with propagation material treatments?
Risk of plant damage
Labor
Equipment and safety
4 methods of vector control
Exclusion
Sticky traps
Reflective mulch
Chemical & biological controls
Vector control ____ ____, but does not ____ ____ ____ _____.
Reduces disease; break the disease cycle
3 methods of host “immunization”
Optimizing plant health
Breeding for resistance
Chemical & biological
Which chemical control product has an irreversible inhibition of the pathogen resulting in death or inactivation?
-cides
Which chemical control product has a reversible inhibition of the pathogen resulting in a slower or temporary halt of the growth?
-stats
Which chemical control kills all life?
Fumigant
What is the most common type of chemical control?
Contact (Protectant)
What type of chemical control is a chemical barrier on the surface of the plant and prevents penetration?
Conact (Protectant)
Contact (protectant) control does/does not move into or through host tissues.
Does not
Which 4 steps could a contact (protectant) control prevent?
Spore germination
Germ tube elongation
Penetration
Colony formation
Which type of chemical control involves an active ingredient moving through plant tissues?
Systemic, Pentrant
What type of penetrant spreads across the waxy surface?
Local penetrant
What type of penetrant moves through the leaf lamina?
Translaminar
What type of penetrant moves in water, between cells and via xylem in a generally upward direction?
Apoplastic
What type of penetrant moves from cell to cell and in phloem in a generally downward direction? (Rare)
Symplastic
What type of penetrant moves both in an upward and downward direction?
Amphimobile
Which systemic activity stops further development of early infections (usually less than 72 hrs)?
Curative
Which systemic activity reduces/halts sporulation from existing lesions?
Antisporulant
What are some problems with “coverage” chemical applications?
Spray pattern, canopy & boundary layer penetration, mechanical abrasion, rainfall, irrigation, UV, wind, tissue expansion (growth)
When the target pest is no longer controlled under normal application rates
Pesticide resistance
5 keys to resistance management
Reduce number of applications Use early, before log phase Alternate chemistries Mix chemistries Substitute or combine with non-chemical controls
What is the industry and government cooperative classifies fungicides into groups by mode of action?
FRAC
FRAC Code
9 groups, by metabolic process inhibited
A-I
FRAC Code
Plant defense inducers
P
FRAC Code Unknown MOA (transient)
U
FRAC Code
Multi-site inhibitors
M
Fungicide registration is based on which 3 things?
Toxicology
Persistence in environment
Persistence on/in food
What 3 ingredients are shown on a product label for chemical control products?
Active ingredient
Formulated product
Adjuvants
Which adjuvant improves spreading?
Surfactant
Which adjuvant improves adherence?
Sticker
What is the length of time after application before workers may reenter a site?
Restricted entry interval
What is the length of time required between final application and harvest?
Pre-harvest interval
What is required and recommended clothing and gear for chemical safety?
Personal protective equipment
Which type of inorganic chemical is phytotoxic at high rates or in cool wet weather? It also has poor solubility.
Copper (Bordeaux mixture)
Which type of inorganic chemical is phytotoxic in hot, dry weather or in some combination with other products (oils, etc)?
Sulfur
4 examples of inorganic chemicals
Copper
Sulfur
Carbonate
Phosphate/phosphonate
Two types of organic chemicals
Contact protective
Systemic
Antibiotics are only effective _____ ____ ______.
Before pathogen penetration
Antibiotics are primarily used for which two pathogens?
Fire blight, bacterial spot of peach
Which type of chemical control is broad spectrum, and therefore used to kill nematodes, insects, fungi, bacteria, weed seeds and many other things?
Soil fumigants
Using one or more living organisms to reduce disease caused by a pathogenic organism
Biological control
How does biological control reduce disease? (4)
Decrease pathogen population (inoculum)
Prevent pathogen from reaching infection court
Prevent infection of the host
Activate host defenses to slow or halt colonization
3 advantages to biological control
Environmental concerns
Durability
Cost?
What was one of the first methods of biological control?
Cats for pest control, Egypt 2000 BC
Insect predation was used in China in 324 BC for what?
Weaver ants for citrus insect pest control
Insect parasitism was used in the US in 1883 how?
Parasitic wasp imported from Europe to control cabbageworm
Fungal biocontrol was used in the US in 1884 how?
First release of mass produced fungi for control of weevil in sugar beet
Bacterial control was used in 1938 how?
First commercial preparation of B. thuringiensis
Progression of Biocontrol (5)
Animal Predation –> Insect predation –> Insect parasitism –> Fungi –> Bacteria
4 ways biocontrol agents work
Predation/parasitism
Competition
Antibiosis
Indirect effects
Which mode of action is when the biocontrol organism uses the target organism as food?
Predation/parasitism
Trichoderma harzianum uses appressoria to prey on other fungi (sclerotinia). What MOA is this?
Predation/parastism
Coniothyrium minitans eats sclerotia hyphae and replaces it with its own. What MOA is this?
Predation/parasitism
Which mode of action is when the biocontrol organism out-competes the target organism for a limited resource?
Competition
What 3 resources are commonly targets for competition?
Space
Nutrients
Water
How does Pseudomonas fluorescens function in competition?
Siderophore, chelates/binds iron tightly so other organisms cannot access it
Which mode of action is when the biocontrol organism produces a substance that inhibits the target organism?
Antibiosis
Which mode of action is when the biocontrol organism has an effect on another organism or on the environment which results in control of the target organism?
Indirect effects
3 ways indirect effects work
Induced resistance in a host
Modulation of pH
Interference with signaling
3 types of biological control application
Classical
Augmentative
Conservation
What type of biological control application is characterized by the target pest/pathogen is introduced (non-native), search for natural enemies in the target’s native range, import and test control organism, and release control organism?
Classical
What type of biological control application is characterized by the target pathogen/pest is native or introduced, natural enemies are native, biocontrol agent is grown elsewhere and introduced to the system?
Augmentative biocontrol
Type of augmentative biocontrol in which small numbers of the agent are released
Inoculative
Type of augmentative biocontrol in which large numbers of the agent are released
Inundative
What type of biological control application includes cultural techniques used to enhance populations of indigenous control agents?
Conservation biocontrol
What does it take to be a good biocontrol agent? (6)
Easy to grow Easy to store Specific to your problem organism Adapted to the site of use Competes well with other organisms Active at the same time as the target
Which problem with biocontrol is when the biocontrol agent is effective against target pest/pathogen, but also effective against non-target organisms?
Lack of specificity
Which problem with biocontrol is when the agent survives well, but is active at the same time? It can also be when a biocontrol fungus doesn’t survive or compete well in the same place as the target organism.
Poorly adapted to site of use
Efficacy of biocontrol depends on which 4 factors?
Environmental factors
Presence of food source
Presence of competitors
Presence of predators/parasites
Which problem with biocontrol involves living organisms vs. chemicals, formulations, and storage requirements?
Shelf life
Which problem with biocontrol involves use of fungicides and interactions among biocontrols?
Interactions with other controls
Which problem with biocontrol includes the “silver bullet” problem and IPM?
User expectations
What are the 6 problems with biocontrol?
Lack of specificity Poorly adapted to site of use Variability in efficacy Shelf life Interactions with other controls User expectations
What pathogenic control method integrates cultural, biological, and chemical control techniques?
IPM
IPM recognizes…
Pest & disease problems cannot be eliminated but may be managed.
The point at which loss from damage exceeds cost of control
Economic injury level
IPM decisions are based on ____ ____ ____.
Economic injury level
3 goals of IPM
Manage disease, pest, and weed problems
Achieve control with lowest possible inputs
Achieve control with least possible impact on environment
7 examples of IPM control measures
Planting material selection Site selection and preparation Planting date Crop nutrition and irrigation Sanitation Monitoring Judicious use of chemical controls
Applications of chemicals made only when certain criteria are met is known as an
action threshold
Action thresholds rely on which two things?
Monitoring, knowledge base
Efficacy of monitoring for IPM…(2)
When curative treatments are available
When spread of pathogen can be halted
In IPM monitoring, when preventative controls are available but not curative or pathogens spread rapidly
Sentinel plots
___ ____ track progress of disease on the landscape level.
Sentinel plots
IPM or Non-IPM?
Applications of pesticide based on the disease triangle
IPM
IPM or Non-IPM?
Applications of pesticide based on a schedule
Non-IPM
4 Advantages of IPM
Can reduce cost of inputs
Can reduce environmental impacts of farming
Can reduce worker risk exposure
Can encourage more sustainable practices
What are two cases in which IPM may be necessary?
No effective chemical controls
Repeated chemical applications are cost-prohibitive
2 problems with IPM
Requires extensive knowledge of pathogen biology and epidemiology
May involve increased labor
How does IPM affect chemical control?
Reduced chemical applications can increase resistance development
