Lecture 4

Question 1

Discuss principle 3 of the IPM principles

Answer 1

1. 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

Question 2

What are the four main considerations for thresholds?

Answer 2

1. The impact of disease losses in vegetation production
2. Complete control of pests is not necessary to ensure profitability
3. Almost all crops can tolerate a certain amount of pest damage
4. 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)

Question 3

What is the EIL?

Answer 3

Economic Injury Level

Question 4

How can we calculate EIL and what do the variables represent?

Answer 4

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

Question 5

Where can we find the action threshold?

Answer 5

When Loss < cost of control

Question 6

Discuss principle 4 of IPM

Answer 6

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.

Question 7

There are two main ways that we can use non chemical methods, in the most basic terms what are they?

Answer 7

We can use products that affect the plant and/or products that affect the pest itself

Question 8

What are 5 general ways that we can affect the plant when considering non-chemical measures for disease control?

Answer 8

1. We can induce resistance via microorganisms (fungi, bacteria)
2. We can induce resistance via natural compounds (vegetal, microbial, animal)
3. Other microorganisms
4. Chemical compounds (Phosphonates)
5. Environmental stress

Question 9

What are 3 general ways that we can affect the pathogen when considering non-chemical measures for disease control?

Answer 9

1. We can promote parasitism, antagonism, and competition via microorganisms
2. We can induce direct toxicity via natural compounds
3. We can induce direct toxicity via botanicals

Question 10

1 example of botanicals and what is the basic principle as to what they target and how they work?

Answer 10

1. 3Logy (Eugeniol, geraniol, timol (terpens))

They target the pathogen and induce direct toxicity

Question 11

EOs include two groups of distinct biosynthetical origin, what are they?

Answer 11

1. main group is composed of terpenes and terpenoids, which contain additional functional groups - (C5H8)n;
2. the other is composed of aromatic and aliphatic constituents.

Question 12

5 strengths of botanicals

Answer 12

1. Effective on epiphytic forms
2. Disinfectant activity (mainly)
3. Useful in anti-resistance strategies
4. Low impacts
5. No residues

Question 13

2 weaknesses of botanicals

Answer 13

1. Short persistence
2. Timing: to be applied at the right moment

Question 14

When using BCA or biocontrol agents what are three things that are necessary for success? (3)

Answer 14

Highly effective biocontrol agent must
* Be able to compete and persist
* Be able to colonize and proliferate
* Be free from negative impacts

Question 15

Examples of parasitism (2)

Answer 15

1. Biogard
2. Sonata

Question 16

What is happening with Antagonism

Answer 16

Inhibition of one organism by another as a result of diffusion of antibiotic compounds

Question 17

Provide an example of an antagonistic BCA

Answer 17

Bacillus subtilis

Question 18

Discuss how competition works

Answer 18

Competition between microorganisms for carbon, nitrogen, O2, iron, and other nutrients.
Most common way organisms limit growth of others.

Question 19

Provide an example of a competitive BCA

Answer 19

Aureobasidium pullulans

Question 20

List 5 strengths of BCA’s

Answer 20

1. Effective with high variability
2. Different mechanisms
3. Useful in anti-resistance strategies
4. Low impacts
5. No residues

Question 21

List 3 weaknesses of BCA’s

Answer 21

1. Timing: to be applied at the right moment
2. Better knowledge needed for exploiting different mechanisms
3. Better knowledge needed about the effect of environmental conditions

Question 22

What are plant resistance inducers?

Answer 22

Plant resistance inducers (PRIs, or elicitors) are chemical compounds able to trigger a resistance response in plants.

Question 23

What are the two states in which we can find PRI’s

Answer 23

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.

Question 24

Difference between fast and intensive defense vs. late and light defense

Answer 24

Fast and intensive will result in little or no disease while late and light defense will result in disease

Question 25

Discuss times of priming and defense responses.

Answer 25

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.

Question 26

What are the three stages of a primed PRI

Answer 26

1. Onset
2. Maintenance
3. Activation

Question 27

What is important to know and consider when applying a PRI that is in a primed state?

Answer 27

How long the maintenance period is

Question 28

What are the three types of costs that we need to consider when discussing defense costs of PRI’s

Answer 28

1. Allocation costs
2. Ecological costs
3. Genetic costs

Question 29

Discuss a cost associated with P. Viticola

Answer 29

P. viticola infection is associated with a cost in CO2 assimilation.

Question 30

5 Strengths of PRI’s

Answer 30

1. Preventative efficacy
2. Variability in effectiveness
3. Useful in anti-resistance strategies
4. Low impacts
5. No residues

Question 31

2 Main weaknesses of PRI’s

Answer 31

1. Metabolic cost for the plant
2. Practical use in disease control to be investigated

Question 32

What is a PRI

Answer 32

Plant resistance inducer