Lecture 5 Part 1 Flashcards

1
Q

End-use products contain one or several ____ and _____

A

Active ingredients and formulants

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2
Q

What is an active ingredient?

A

Substances or micro-organisms, including viruses, having general or specific action against harmful organisms on plants, parts of plants or plant products, and constituting a product to which is linked the pesticide’s effect.

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3
Q

What is a formulant?

A

Any substance or group of substances other than the active ingredient that is intentionally added to a pest control product to improve its characteristics

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4
Q

Pesticides are classified by their target organism, give two examples

A
  1. Herbicide for plants
  2. Fungicides for fungi
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5
Q

Plant protection product: products consisting of or containing active substances, safeners or synergists, and intended for one of the following uses: (5)

A
  1. Protecting plants or plant products against all harmful organisms
  2. Influencing the life processes of plants
  3. Preserving plant products
  4. Destroying undesired plants or parts of plants
  5. Checking or preventing undesired growth of plants
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6
Q

Broadly what are the three main reasons why fungicides are used?

A
  1. To control a disease during the establishment and development of a crop.
  2. To increase productivity of a crop and to reduce blemishes.
  3. To improve the storage life and quality of harvested plants and produce.
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7
Q

What is principle 5 of IPM

A

Principle 5 is to target-specificity and minimization of side effects of pesticides

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8
Q

What are the three main selection criteria for PPP’s

A
  1. Human helath
  2. The environment
  3. The Efficacy
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9
Q

In terms of efficacy as a consideration for selection of pesticide criteria what three main things do we need to take into account?

A
  1. MoA (Mode of action) Spectrum and risk of resistance
  2. PhMoA/PMoA (Physical mode of action) activity and use of pesticide
  3. Risk of resistance (Principle 7)
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10
Q

What do we consider in regard to the MoA?

A

Site and mechanism of action: cellular components subject to the fungicide action (target sites) and mechanisms that made the fungicide effective.

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11
Q

What are three types of MoA fungicides?

A
  1. Multi-site fungicides (have more sites and modes of action)
  2. Site-Specific fungicides (have only one site and one mode of action)
  3. Spectrum fungicides (range of fungi hit by the fungicide; could be broad spectrum fungicides or specific fungicides)
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12
Q

What does PMoA describe?

A

the effect of a fungicide with respect to the time of its placement in relation to the host-pathogen interaction.

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13
Q

What are the three main things that PMoA considers?

A
  1. Fungicide activity
  2. Fungicide localization with respect to the plant
  3. Duration and degree of the fungicide activity
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14
Q

what are the four activities in which fungicide activity considers?

A
  1. Pre-infection activity (preventative)
  2. Post-infection (curative)
  3. Pre-symptom
  4. Post-symptom (eradicant)
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15
Q

What are the two groups that fungicides can be broken up into?

A
  1. Protectant (non-penetrative)
  2. Systemic (Penetrative)
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16
Q

Penetrant fungicides are systemic to different degrees, what are they (4)

A
  1. Locally systemic
  2. Fully systemic
  3. Xylem systemicity
  4. Phloem systemicity
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17
Q

Five main attributes of contact fungicides

A
  1. Not Absorbed
  2. Not-mobile
  3. Preventative
  4. Multi-site of action
  5. No or few resistance
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18
Q

Five main attributes of penetrative fungicides

A
  1. Absorbed
  2. Mobile
  3. Preventative + curative
  4. Often single site of action
  5. Fungi can develop resistance
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19
Q

After a fungicide is applied, fungicide residues progressively decrease over time due to: (5)

A
  1. Weathering
  2. Chemical deterioration
  3. Microbial activities on plant surface
  4. Redistribution over the plant
  5. Fungicide dilution by plant growth
20
Q

Discuss decay kinetics

A

A constant decay is very rare, they are usually exponential

21
Q

7 Fates of the fungicide after treatment

A
  1. Adhesion of the droplets
  2. Drying out
  3. Redistribution on the surface with leaf wetness
  4. Redistribution in the vapor phase
  5. Redistribution with rains and wash-off by rains
  6. Uptake by the plant
  7. Endophytic movement and dilution

6,7 are for penetrative

22
Q

Rainfastness:

A

The time required between application on the plant surface and rain for the product to be effective in controlling the target organism.

23
Q

Fungicide tenacity

A

Is the ability of the fungicide to resist to rainfall wash-off.

24
Q

Attenuation factor

A

Disappearance of canopy applied fungicides from plant tissue

25
Q

What do we know about the attenuation factor when graphed and measured

A
  1. Fungicide residue disappears much more quickly post-infection rather than pre-infection
26
Q

Wash-off by rainfall

A

In case of rainfall, the fungicide residue on the plant surface is reduced based on the precipitation amount

27
Q

What is principle 7 of IPM

A

Application of anti-resistance strategies

28
Q

How do we get resistance

A

The extensive use of pesticides has often resulted in the development and evolution of pesticide resistance in insect pests, plant pathogens, and weeds.

29
Q

Define fungicide resistance

A

Stable, inheritable adjustment by a pathogen to a fungicide, resulting in reduced sensitivity of the pathogen to fungicide

30
Q

First of five origins and development of fungicide resistance

A
  1. Resistant fungal strains are already present in the pathogen population, caused by naturally-occurring genetic variability and mutations
31
Q

Second of five origins and development of fungicide resistance

A

Fungicide applications select for these resistant pathogen biotypes: fungicides kill the fungicide-sensitive population and only resistant biotypes survive

32
Q

Third of five origins and development of fungicide resistance

A

Repeated use of the particular fungicide exerts selection pressure in the fungal population

33
Q

Fourth of five origins and development of fungicide resistance

A

As a consequence, the population of resistant pathogen biotypes increases and replaces the sensitive population

34
Q

Fifth of five origins and development of fungicide resistance

A

Further applications of the fungicide fail in disease control

35
Q

What are the two types of resistance build-ups

A
  1. Qualitative
  2. Quantitative
36
Q

What is qualitative resistance build-up? (3)

A
  1. Fast occurrence
  2. Associated with site-specific fungicides
  3. Complete loss of disease control
37
Q

What is quantitative build-up? (3)

A
  1. Develops over time
  2. Associated with multi-site fungicides
  3. Varying degree of disease control
38
Q

A fungicide has a specific target site where it acts to disrupt a particular biochemical process or function. If this target site is somewhat altered, the fungicide no longer binds to the site of action and is unable to exert its toxic effect.
This is the most common mechanism that fungi use to become resistant.

A

Mutated target site

39
Q

Overexpression

A

Overexpression of the target site (e.g. a protein) increases the concentration of fungicide necessary for inhibition.

40
Q

5 Fungicide resistance mechanisms

A
  1. Mutated target site
  2. Overexpression
  3. Removal
  4. Detoxification or metabolism
  5. Reduced uptake
41
Q

A fungal cell may rapidly export the
fungicide before it can reach the target site of action.

A

Removal

42
Q

Metabolism within the fungal cell is one
mechanism a disease pathogen uses to detoxify a foreign compound such as a fungicide. A fungus with the ability to quickly degrade a fungicide can potentially inactivate it before it can reach its site of action.

A

Detoxification or metabolism

43
Q

The resistant pathogen simply absorbs the fungicide much more slowly than the susceptible type.

A

Reduced uptake

44
Q

What is the Combined risk of fungicide resistance pyramid made up of (4)

A
  1. Fungicide risk
  2. Pathogen risk
  3. Agronomic risk
  4. Overall resistance risk
45
Q

Pathogen population that is resistant to one fungicide within a group develops resistance over other members of the same group

A

Cross resistance

46
Q

Pathogen population shows resistance to fungicides from more than one chemical group

A

Multiple resistance