Lecture 4 Flashcards
Discuss principle 3 of the IPM principles
- Principle three is about threshold values as basis for decision making. Based on monitoring we can find our thresholds and decide whether and when to apply plant protection measures
What are the four main considerations for thresholds?
- The impact of disease losses in vegetation production
- Complete control of pests is not necessary to ensure profitability
- Almost all crops can tolerate a certain amount of pest damage
- Work is therefore centered around determining the relationship between damage levels and crop yields to establish thresholds (allowable levels of damage or pest population densities)
What is the EIL?
Economic Injury Level
How can we calculate EIL and what do the variables represent?
EIL = C/(V x DI x K)
C: Pest management costs, V: Yield market value
DI: Yield loss per pest, K: Proportion of the pest population controlled
Where can we find the action threshold?
When Loss < cost of control
Discuss principle 4 of IPM
Principle 4 is: Non-chemical methods to be preferred
Sustainable biological, physical and other non-chemical methods must be preferred to chemical methods if they provide satisfactory pest control.
There are two main ways that we can use non chemical methods, in the most basic terms what are they?
We can use products that affect the plant and/or products that affect the pest itself
What are 5 general ways that we can affect the plant when considering non-chemical measures for disease control?
- We can induce resistance via microorganisms (fungi, bacteria)
- We can induce resistance via natural compounds (vegetal, microbial, animal)
- Other microorganisms
- Chemical compounds (Phosphonates)
- Environmental stress
What are 3 general ways that we can affect the pathogen when considering non-chemical measures for disease control?
- We can promote parasitism, antagonism, and competition via microorganisms
- We can induce direct toxicity via natural compounds
- We can induce direct toxicity via botanicals
1 example of botanicals and what is the basic principle as to what they target and how they work?
- 3Logy (Eugeniol, geraniol, timol (terpens))
They target the pathogen and induce direct toxicity
EOs include two groups of distinct biosynthetical origin, what are they?
- main group is composed of terpenes and terpenoids, which contain additional functional groups - (C5H8)n;
- the other is composed of aromatic and aliphatic constituents.
5 strengths of botanicals
- Effective on epiphytic forms
- Disinfectant activity (mainly)
- Useful in anti-resistance strategies
- Low impacts
- No residues
2 weaknesses of botanicals
- Short persistence
- Timing: to be applied at the right moment
When using BCA or biocontrol agents what are three things that are necessary for success? (3)
Highly effective biocontrol agent must
* Be able to compete and persist
* Be able to colonize and proliferate
* Be free from negative impacts
Examples of parasitism (2)
- Biogard
- Sonata
What is happening with Antagonism
Inhibition of one organism by another as a result of diffusion of antibiotic compounds
Provide an example of an antagonistic BCA
Bacillus subtilis
Discuss how competition works
Competition between microorganisms for carbon, nitrogen, O2, iron, and other nutrients.
Most common way organisms limit growth of others.
Provide an example of a competitive BCA
Aureobasidium pullulans
List 5 strengths of BCA’s
- Effective with high variability
- Different mechanisms
- Useful in anti-resistance strategies
- Low impacts
- No residues
List 3 weaknesses of BCA’s
- Timing: to be applied at the right moment
- Better knowledge needed for exploiting different mechanisms
- Better knowledge needed about the effect of environmental conditions
What are plant resistance inducers?
Plant resistance inducers (PRIs, or elicitors) are chemical compounds able to trigger a resistance response in plants.
What are the two states in which we can find PRI’s
Induced or Prime state
In this case the difference is that the primed state PRI’s are able to to mount enhanced future defence responses following pest or pathogen attack, or exposure to particular environmental conditions or externally applied chemicals.
Difference between fast and intensive defense vs. late and light defense
Fast and intensive will result in little or no disease while late and light defense will result in disease
Discuss times of priming and defense responses.
The timing of priming is incredibly important as we want the defenses of the plant to be highest after the pathogen has attacked and is ready to penetrate and invade. Times of priming affects application strategies of resistance inducers (timing) and their efficacy in disease control.
What are the three stages of a primed PRI
- Onset
- Maintenance
- Activation
What is important to know and consider when applying a PRI that is in a primed state?
How long the maintenance period is
What are the three types of costs that we need to consider when discussing defense costs of PRI’s
- Allocation costs
- Ecological costs
- Genetic costs
Discuss a cost associated with P. Viticola
P. viticola infection is associated with a cost in CO2 assimilation.
5 Strengths of PRI’s
- Preventative efficacy
- Variability in effectiveness
- Useful in anti-resistance strategies
- Low impacts
- No residues
2 Main weaknesses of PRI’s
- Metabolic cost for the plant
- Practical use in disease control to be investigated
What is a PRI
Plant resistance inducer
