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Plant 160 Lab HMOA - HERBICIDE MODE OF ACTION LAB

HERBICIDE MODE OF ACTION LAB
Course

Weed Science (PLTH 105)

10 Documents
Students shared 10 documents in this course
Academic year: 2018/2019
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California State University Fresno

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PLANT 160 (10 points as part of Lab score)

Name: Kelsey Galvan

HERBICIDE MODE OF ACTION LAB April 13, 15 & 17

1. Go to the website: passel2.unl/list/lesson

Select ‘Herbicide Classification’

View it – click on next topic as you go along

Answer the following questions:

i) In which decade did the development of herbicides rapidly increase?

1970s

ii) How many modes of action are there currently? List them

8 modes of action:

  1. Lipid Synthesis Inhibition
  2. Amino Acid Synthesis Inhibition
  3. Seedling growth inhibition
  4. Growth regulators
  5. Photosynthesis inhibition
  6. Cell membrane disruption
  7. Pigment inhibition
  8. “Unclassified or “Unknown” (regulation or inhibition of plant functions)

iii) What is the meaning of herbicide family?

A group of herbicides that has the same name based on their relation to its chemical similarities.

iv) What is the difference between site of absorption and site of action?

Site of absorption is the location where the herbicide is taken up by the plant. Whereas, site of action is the biochemical pathway within the plant where the herbicide takes action.

v) Study the modes of actions and briefly describe what the mode of action is and what the injury symptoms are. Provide two examples of herbicides for each mode of action and verify if that particular herbicide is labeled in California (for this you will need to go to: home.agrian/ and then select Label Lookup).

  1. Lipid synthesis inhibitors: inhibits the synthesis of the a plant lipids, and presence of no lipids disrupts the production of cell membranes, and new plant growth is halted. Plant

injury includes purpling and eventually death at the growing point of the plant. Ex: Assure II and Poast, both not verified in California 2) Amino Acid Synthesis inhibitors: prevents production of amino acids, the proteins for plant growth and development. Injury symptoms include red and purple color at the base of the stem. Ex: Classic (not verified in CA) and Roundup (verified in CA) 3) Seedling growth inhibitors: interrupts the new plant growth and development and inhibits root and shoot growth in emerging plants. Injury symptoms include tiny plants that have not reached maturity. Ex: Treflan (not verified in CA) and Prowl (verified in CA) 4) Growth regulators: mimic auxins and cause the plant to undergo rapid and uncontrolled growth and the hormone isn’t completely understood causing the plant to die. Injury symptoms include huge weeds that grow, and use all the energy and die. Ex: Clarity and Stinger, both verified in CA 5) Photosynthetic inhibitors: inhibit the binding site of photosynthesis and has a secondary destructive compound that is produce during the inhibition of photosynthesis and causes plant death. Injury symptoms include necrosis of new leaf growth. Ex: Atrazine (not verified in CA) and Senecor (verified in CA) 6) Cell membrane disruptors: react with the plant to form compounds such as super oxides and hydroxyl radicals, which will destroy the cell membranes. Injury symptoms include interveinal necrosis. Ex: Cobra and Gramoxone, both are not verified in CA 7) Pigment Inhibitors: prevent production of compounds that protect the plant from chlorophyll destruction and instead of it being green, the plant tissue will turn into a pale yellow, and then white. Injury symptoms include the results of the plant exhibiting white tissue. 8) Unknow: Few herbicides mode of action are classified as ‘unkown’. The mode of action is not understood or isn’t classified. Ex: MSMA and Nortron, both verified in CA

2. Go to the animations site:

passel2.unl/view/media?view=animations

  1. View

i) Sub-soil contact: A herbicide applied to the soil subsurface is incorporated into the soil through tillage or rain. Herbicide root uptake occurs through the xylem with water, and when the herbicide is sprayed on the plant it goes through shoot uptake. The herbicide will move from a higher concentration to a lower concentration, which is how it moves through plant.

ii) Herbicide metabolism-Conjugation: This include the conjugation of herbicides which is when the herbicide is adsorbed to another compound. The three include: glutathione conjugation, which it a triptide that involves the three amino acids glutamate, cysteine, and glycine, then there’s sugar conjugation, where sugars like glucose can attach to the herbicide, and then glucose ester formation forms through acid groups.

vi) Why is the transfer of electrons from Photosystem II to Photosystem I essential?

This is essential for the production of photosynthetic energy

vi) Which photosystem does paraquat interact with?

Photosystem I

  1. Select the module “Cellular absorption of herbicides”

passel2.unl/view/lesson/9e46d907153e

Answer the following questions:

i) Explain the terms lipophilicity and hydrophilicity

Lipophilicity: ability to dissolve lipids and acidity properties; lipid solubility; more hydrocarbons the more lipophilic

Hydrophilicity: more water soluble, more attracted to water

ii) What is the difference between passive and active absorption? Passive absorption: driven through diffusion, moving down a concentration gradient from a higher to lower concentration, passively absorbed into plant cells Active absorption: molecule moves across a membrane against concentration gradient, involves protein carrier and uses energy to get to move the herbicide from one side to the other of the membrane iii) Provide a short summary on what you learned in this particular module.

For an herbicide to get to its site of action, it has to go through barriers first and many characteristics of the plant can affect the absorption of the herbicide at the site of action. Plant cells are using passive and active transports to be able to get the herbicide absorbed. The form of the herbicide matters, and the solubility is important to be able to get it absorbed in the site of action, that way it isn’t a waste of a spray. The goal is to contribute phytotoxicity to the desired plant.

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Plant 160 Lab HMOA - HERBICIDE MODE OF ACTION LAB

Course: Weed Science (PLTH 105)

10 Documents
Students shared 10 documents in this course

University: California State University Fresno

Was this document helpful?
PLANT 160 (10 points as part of Lab score)
Name: Kelsey Galvan
HERBICIDE MODE OF ACTION LAB April 13, 15 & 17
1. Go to the website: https://passel2.unl.edu/list/lesson
Select ‘Herbicide Classification’
View it – click on next topic as you go along
Answer the following questions:
i) In which decade did the development of herbicides rapidly increase?
1970s
ii) How many modes of action are there currently? List them
8 modes of action:
1) Lipid Synthesis Inhibition
2) Amino Acid Synthesis Inhibition
3) Seedling growth inhibition
4) Growth regulators
5) Photosynthesis inhibition
6) Cell membrane disruption
7) Pigment inhibition
8) “Unclassified or “Unknown” (regulation or inhibition of plant functions)
iii) What is the meaning of herbicide family?
A group of herbicides that has the same name based on their relation to its chemical similarities.
iv) What is the difference between site of absorption and site of action?
Site of absorption is the location where the herbicide is taken up by the plant. Whereas, site of
action is the biochemical pathway within the plant where the herbicide takes action.
v) Study the modes of actions and briefly describe what the mode of action is and what the injury
symptoms are. Provide two examples of herbicides for each mode of action and verify if that
particular herbicide is labeled in California (for this you will need to go to:
https://home.agrian.com/ and then select Label Lookup).
1) Lipid synthesis inhibitors: inhibits the synthesis of the a plant lipids, and presence of no
lipids disrupts the production of cell membranes, and new plant growth is halted. Plant

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