Lecture 13 group 1 Flashcards
Herbicide Modes of Action
What do Group 1 herbicides inhibit?
Fatty acid / lipid biosynthesis
ACCase inhibitors
is there high soil residual for group 1’s?
no - rapidly degraded in soil (microbial)
what tissues do group 1’s damage?
meristem tissue
do group 1’s effect broadleaves?
no
three classes of group 1 ACCase inhibitors
1) Aryloxyphenoxy Propionates - “fops”
2) Cyclohexanediones - “dims”
3) Phenylpyrazolin - “dens”
Aryloxyphenoxy Propionates “fops” properties
pro - herbicides with methyl, ethyl and butyl groups
Typically parent is acid so needs alcohol group to move past into plant
Aryloxyphenoxy Propionates - Fops, Dims or Dens?
Fops
Cyclohexanediones “dims” properties
photodegredate, breakdown when exposed to light
Cyclohexanediones - Fops, Dims or Dens?
Dims
Phenylpyrazolin “dens”
newest class
Phenylpyrazolin - Fops, Dims or Dens?
Dens
Aryloxyphenoxy Propionates (AOPP) examples
Clodinafop - propargyl
Fenoxaprop-p-ethyl
Fluizafop-p-butyl
Quizalofop
Cyclohexanediones (CD) examples
Clethodim
Sethoxydim
Tepraloxydim
Tralkoxydim
Phenylpyrazolin example
Pinoxaden
group 1 MOA and injury
- inhibit enzyme Acetyl CoA Carboxylase (ACCase) -> essential for fatty acid biosynthesis for membrane production
- loss of cell integrity
- injury at growth point, yellowing, inhibit meristem, young leaves pull out
Chlorosis
Plant yellowing due to loss of chlorophyll
Necrosis
Localized death of living tissue
two forms of selectivity
1) enzyme bonding affinity
2) differential metabolism
Enzyme binding affinity - selectivity monocots vs dicots
Dicots - low enzyme bonding affinity
Monocots - high enzyme bonding affinity
differential metabolism - selectivity
Monocots - differential metabolism
Weeds vs. crops
