Lecture 13 group 2

Question 1

What do group 2 herbicides inhibit?

Answer 1

Branched chain amino acid biosynthesis

Question 2

do group 2’s have a high or low dose chemistry and soil persistence?

Answer 2

low concentration, high soil residual

Question 3

what is the largest herbicide group?

Answer 3

group 2

Question 4

group two families

Answer 4

• Imidazolinones
• Sulfonylureas
• Sulfonylaminocarbonyltriazolinone

-Triazolopyrimidine sulfonanalide

Question 5

Sulfonylurea examples

Answer 5

Thifensulfuron

Tribenuron

Metsulfuron

Sulfosulfuron

Ethametsulfuron

Rimsulfuron

Nicosulfuron

Question 6

Imidazolinone examples

Answer 6

Imazamethabenz

Imazethapyr

Imazamox

Question 7

Triazolopyrimidine

Answer 7

Florasulam

Pyroxsulam

Question 8

Sulfonylaminocarbonyltriazolinone

Answer 8

flucaebanazone - sodium

Thiencarbazone - methyl

Question 9

Group 2 MOA

Answer 9

• inhibit branch chain amino acids synthesis
• no new growth possible
• shut down of growth point at low dose

Question 10

group 2 target site

Answer 10

ALS or AHS - chloroplast and plastids

Question 11

group 2 selectivity

Answer 11

-based on differential metabolism rates

-mixed susceptibility between monocots and dicots

Question 12

group 2 soil persistence

Answer 12

varies by herbicide

SU and IMI’s have opposite response to soil pH

increased group 2 use causes ‘stacking’ - re-cropping can be a problem

Question 13

SU’s response to pH

Answer 13

High pH soils increase in persistence of SU’s

Question 14

IMI’s response to pH

Answer 14

Low pH increases persistence of IMI