With reference to weedicides, consider the following statements: 1. They are chemicals used to control weeds. 2. They are sprayed to kill the main crop along with the weeds. 3. They are best sprayed during the vegetative growth of weeds before flowering. Which of the statements given above is/are correct?

The correct option is (c) 1 and 3 only. Explanation Weedicides are specific chemical substances employed in agriculture to suppress or eliminate unwanted plant growth (weeds) that competes with cultivated crops for nutrients, space, and light. Common examples include 2,4-D (2,4-Dichlorophenoxyacetic acid), which acts as a synthetic auxin. - Statement 1 is Correct: Weedicides are chemicals explicitly designed and used to control weeds. They are diluted with water and sprayed in the fields to inhibit the growth of unwanted vegetation. - Statement 2 is Incorrect: Weedicides are formulated to be selective in nature. They destroy the weeds but do not damage the main crop when used in appropriate concentrations. If they killed the main crop, the purpose of agricultural protection would be defeated. - Statement 3 is Correct: The efficacy of weedicides is highest when applied during the vegetative growth phase of weeds, specifically before they flower and produce seeds. Once weeds reach the flowering or seed-setting stage, they become more resistant to chemicals, and the risk of seed dispersal increases. Key Takeaway: Weedicides are selective chemicals used to eliminate weeds without harming the primary crop. They must be applied during the vegetative stage (before flowering) for maximum effectiveness.

With reference to weedicides, consider the… - NCERT Class 8 Science MCQ

NCERT Class 8 Science — Chapter 1: Crop production and management

mcqmedium

With reference to weedicides, consider the following statements:

They are chemicals used to control weeds.
They are sprayed to kill the main crop along with the weeds.
They are best sprayed during the vegetative growth of weeds before flowering.

Which of the statements given above is/are correct?

NCERT textbook question

From NCERT Science - class 8 · Page 10

Options

A1 and 2 only
B2 only
C1 and 3 only
D1, 2 and 3

Did you get this right?

Solution

The correct option is (c) 1 and 3 only.

Explanation

Weedicides are specific chemical substances employed in agriculture to suppress or eliminate unwanted plant growth (weeds) that competes with cultivated crops for nutrients, space, and light. Common examples include 2,4-D (2,4-Dichlorophenoxyacetic acid), which acts as a synthetic auxin.

Statement 1 is Correct: Weedicides are chemicals explicitly designed and used to control weeds. They are diluted with water and sprayed in the fields to inhibit the growth of unwanted vegetation.
Statement 2 is Incorrect: Weedicides are formulated to be selective in nature. They destroy the weeds but do not damage the main crop when used in appropriate concentrations. If they killed the main crop, the purpose of agricultural protection would be defeated.
Statement 3 is Correct: The efficacy of weedicides is highest when applied during the vegetative growth phase of weeds, specifically before they flower and produce seeds. Once weeds reach the flowering or seed-setting stage, they become more resistant to chemicals, and the risk of seed dispersal increases.

Key Takeaway:

Weedicides are selective chemicals used to eliminate weeds without harming the primary crop. They must be applied during the vegetative stage (before flowering) for maximum effectiveness.

Your note

More from Chapter 1: Crop production and management

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