Lecture 15 - Group 9 Flashcards
mode of action of group 9
inhibitors of aromatic amino acids
what is the only chemical in group 9
glyphosate
what is the most widely used herbicide on the planet
glyphosate
what kind of weeds does glyphosate (group 9) control
non selective, so it works on both annual and perennial grass and broadleaf weeds
grasses are ______ susceptible than broadleaves to group 9/glyphosate
more
how many different salts is glyphosate supplied as
4
what do you want to avoid when using glyphosate and how can you fix it
using hard water, as it can deactivate herbicide prior to spraying
AMS can overcome this problem
how does group 9 mode of action work
works on shikima pathway and inhibits EPSP synthase, which is essential in creation of aromatic amino acids, and cause buildup of toxic intermediates and blocks formation of cytochrome and chlorophyll a
symptoms of group 9
- see symptoms on newest leaves
- yellowing in growing point
- growth ceases quickly
- necrosis in 1-3 weeks
- leaf twisting sometimes
- purpling and yellowing
selectivity of group 9
- timing of application can influence selectivity
- have glyphosate resistant crops
- cuticle thickness
2 main mechanisms of resistant weed biotypes
- altered target site
- reduced translocation
how many species have developed resistance to glyphosate
32 species
mode of action of group 10
inhibitors of glutamine synthetics
group 10 herbicides
glufosinate ammonium
what is group 10 used on
non selective, contact herbicide, but is weak on perennial weeds
how does group 10 mode of action work
bind to active site of GS and cause accumulation of excess of ammonia and deplete amino acids that use N. Also indirectly inhibit photosynthesis due to lack of glutamine
symptoms of group 10
- spotted bronzing
- chlorosis and wilting in 3-5 days
- necrosis in 1-2 weeks
- symptoms increase from bright sunlight, high humidity, and moist soil
basis of selectivity of group 10
almost non-selective, as it is metabolized in all plants but not quickly enough to avoid toxicity
peculiarities of group 10
- control is reduced at less than 10C, low humidity, fog, or dew
- has herbicide resistant crops
- relatively low risk of resistance
