Pesticide Uptake And Movement Flashcards
Factors affecting pesticide uptake
- doesn’t hit the leaves
- runoff
- evaporation
- adsorption
Why is foliage uptake important?
Surface pesticides can be washed off or degraded by UV
Herbicides NEED to be uptaken
Systemic insecticides and fungicides need to be uptaken
What’s the barrier to foliar uptake?
The cuticle
Factors affecting movement through cuticle
- temperature
- humidity
- surfactants
What’s a surfactant?
amphiphilic (hydrophobic and hydrophilic ends)
Breaks surface tension so droplet has more contact with leaf tissue
Are the following hydrophobic or hydrophilic?
- Cuticle
- Cell wall
- Cell membrane
- Both
- Hydrophilic
- Hydrophobic
Apoplastic vs symplastic
Apoplastic - between cells. Hydrophilic. Goes to xylem
Symplastic - through cells. Hydrophobic. Goes to phloem
Eventually needs to be symplastic to get through the casparian strip and enter the root
Is phloem or xylem mobility better?
Phloem bc phloem moves up and down whereas xylem just brings water up so pesticides wouldn’t get to the roots
How do insects/animals uptake pesticides?
- orally
- skin
- inhalation
Best life stage to target insects
Most of the time it’s larvae because they don’t have waxy exoskeleton and they’re the stage that does the damage
Two types of fungicides
Protectant
- coats plant and prevents spore germination and is barrier between the plant and the fungi
Captan
Curative
- taken up and translocated
- can be applied after spore germination
Layers of insect cuticle
Epicuticle - prevent desiccation
Exocuticle - stiff layer
Endocuticle - flexible layer
Epidermal cells
How does a pesticide be toxic to an insect?
Rate of penetration > rate of metabolism
