1.
PREPARED BY: GROUP 5
IMPACT OF WEED
CONTROL

2.
OBJECTIVES
1. Define the term "weed."
2. The impact of weeds on the environment
3. The impact of weeds on agriculture
4. The impact of weeds on human health
5. The Five (5) General Categories of Weed Control
6. The Impact of weed control

3.
What is Weeds?
Weeds are plants which are undesirable,
persistent, damaging and interfere with growth of
other crop plants thus affecting human activities,
agriculture, natural processes and economy of
the country.

4.
Weeds can impede the proper development of a crop
as they:

5.
The impact of weeds on the environment
Weeds are one of the major threats to farmers natural
environment. Major weed invasions change the natural
diversity and balance of ecological communities. These
changes threaten the survival of many plants and animals
because the weeds compete with native plants for space,
nutrients and sunlight.

6.
The impact of weeds on agriculture
Weeds reduce farm and forest productivity, they
invade crops, smother pastures and in some cases can harm
livestock. They aggressively compete for water, nutrients and
sunlight, resulting in reduced crop yield and poor crop quality.
For example, prickle bushes such as Gorse, Blackberries,
Prickly Acacia, Parkinsonia and Mesquite can invade vast
areas of grazing land preventing productive use of that land.

7.
The impact of weeds on human health
Weeds can also cause human health
problems. Many common weeds such as
Parthenium Weed, Ragweed, Rye Grass and Privet
cause asthma and other respiratory problems,
especially in children. Some weeds can also cause
skin irritation and some are poisonous.

8.
The 5 general categories of weed control are:
1. Preventative Weed Control
2. Cultural Weed Control
3. Mechanical Weed Control
4. Biological Weed Control
5. Chemical Weed Control

9.
Preventative Weed Control
• Preventative weed control refers to any control method that aims to
prevent weeds from being established in a cultivated crop, a pasture, or a
greenhouse.
Cultural
• Cultural weed control refers to any technique that involves maintaining
field conditions such that weeds are less likely to become established
and/or increase in number.
Mechanical
• Mechanical weed control refers to any technique that involves the use of
farm equipment to control weeds. The two mechanical control techniques
most often used are tillage and mowing.

10.
Biological
• Biological weed control refers to any technique that involves the
use of natural enemies of weed plants to control the
germination of weed seeds or the spread of established plants.
This is a rapidly expanding area of weed control with many
examples.
Chemical
• Chemical weed control refers to any technique that
involves the application of a chemical (herbicide) to
weeds or soil to control the germination or growth of the
weed species.

11.
• Weed control is vital to agriculture, because weeds decrease yields,
increase production costs, interfere with harvest, and lower product quality.
Weeds also impede irrigation water-flow, interfere with pesticide
application, and harbour disease organisms.
• Weed control, in any event, has become a highly specialized activity.
Universities and agricultural colleges teach courses in weed control, and
industry provides the necessary technology. In agriculture, weed control is
essential for maintaining high levels of crop production.
• Weed control is having a far-reaching impact on all phases of crop
production. New chemical, cultural, mechanical, biological, and
combination methods of weed control affect crop choice; the variety to use;
method of seeding; seeding rates; row spacing; plant spacing in the row;
fertilizer practices including type, time of application, and placement.

12.
Thank You