“herbicides” mode of action reeves petroff pesticide education specialist et al. msu extension
TRANSCRIPT
“Herbicides”
Mode of Action
Reeves PetroffPesticide Education Specialist et al.
MSU Extension
Classification of Herbicides Application Method
Foliar Applied• Plant contact
Soil Applied• Soil contact
Broadcast• Entire area
Spot• Specified area
Classification of Herbicides Application Timing
Preemergence• Prior to seed
germination Postemergence
• After seed germination and active growth
Post-directed• Directed to
particular portion of plant once emerged and growing
Classification of Herbicides Plant/Soil
Environment Selectivity
• Selective vs nonselective
Systemic• Mobile vs non-
mobile in the plant Residual Activity
• Extended vs non-extended soil activity
Classification of Herbicides Mechanism of
Activity Mode of action (MOA)
How it kills
Herbicide Modes of Action
1. Plant Growth Regulation 2. Photosynthesis Inhibitors 3. Photosynthetic Pigment Inhibitors 4. Plant Growth Inhibitors 5. Amino Acid Synthesis Inhibition 6. Lipid Biosynthesis Inhibition 7. Cell Membrane Disruption 8. Unclassified Activity
Types of Herbicide Injury 1. Plant Growth Regulation 2. Photosynthesis Inhibitors 3. Photosynthetic Pigment Inhibitors 4. Plant Growth Inhibitors 5. Amino Acid Synthesis Inhibition 6. Lipid Biosynthesis Inhibition 7. Cell Membrane Disruption 8. Unclassified Activity
Mechanism of Action & Herbicides Used
Plant Growth Regulating Herbicides
Plant Growth Regulation Mimics natural plant hormone –
Auxins. Results in an imbalance of this growth
regulating hormone. Cells of the leaf vein rapidly divide while
cells between the veins do not. Cell division and respiration increase,
while photosynthesis does not.
Common Leaf Symptoms from PGR Exposure
normal
cupped and blistered from PGR exposure
short internode
accumulation In new growth
Foliar PGR Application
callus formation on roots
translocation to growing point
swollen hypocotyl
lack of root development
Root Absorption of Plant Growth Regulator
Herbicides
Plant Growth Regulation Examples include:
2,4-D Dicamba Picloram Clopyralid Triclopyr
Mechanism of Action & Herbicides Used
Amino Acid Synthesis Inhibiting Herbicides
Amino Acid Synthesis Inhibition Amino Acids = life!! Specific to plant AAs only Visual results are the result of
secondary injury the injury as the beginning of a chain of
events that take place in the plant. symptoms take time to develop – it is
not an immediate process.
Amino Acid Synthesis Inhibition
Amino Acid Synthesis Inhibition What are you going to see visually?
Initially there will be a general yellowing of the treated plants.
After 5 to 10 days, chlorosis results in necrosis.
Plateau or Escort Injury Symptoms
Stunting
Chlorosis ofyoungest tissue
Glyphosate (Roundup) Drift
chlorosisshortened internodes
stem proliferation
Amino Acid Synthesis Inhibition Imidazolinones
Arsenal Plateau Sahara Top Site
Glyphosate Roundup
Sulfonylureas Escort Oust Telar
Summary Ideas Know symptoms
associated with the different classes of herbicides
Can more easily understand what to expect?.
Summary Just Remember:
“Worrying has killed more people than work because more people worry than work.”