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9 May 2018

WEED CONTROL MEASURES


6.4 Weed control measures
There are several methods used in weed control. They can classified into:
(a) Mechanical or physical method.
(b) Cultural method.
(c) Biological method.
(d) Chemical method.
(a) Mechanical or physical method



(i) Hand pulling: 1 this is the pulling of weeds by hand in the farm. Though it is efficient, but only useful in small gardens and not large farms.

(ii) Hoeing: The short or small hoe is very useful in weeding. It is used to cut the weed below the crown of the plant which gives, complete destruction of the shoot system. It is effective in the control of weeds either in pasture, home garden or row crops. Hoe can be used to weed from the furrow to the top of a ridge. Its use is however on a limited and it requires plenty of labour.

(iii) Mowing: This method helps to prevent seed production in till of weeds. It removes all unsightly weed growth especially where weeds are too much for effective cultivation to take place. The method can be used to control weeds in lawns, plantation or fields. The mower is normally attached to a tractor or pulled by hand to move over the area to be cleared.

(iv) Flooding: This is done by keeping the area to be weeded Hooded up to 20 cm of water for 3 to 8 weeks. This practice kill, the weeds because they can no longer receive air for a-.piration.

(v) Heat treatment: Heal can be used in controlling weeds. For instance nursery soil is sterilized to kill all weed parts and seeds. Fire ran be used to burn dry weeds on cultivated land before cultivation starts





(vi) Smothering with non-Living materials: Weeds can be Followed by the use of mulch materials such, as papers, hulls from rice, manure, plastic materials or cellophane. These materials help to exclude sunlight and prevent shoot growth. The weeds then become etiolated (lose chlorophyll) and die off.

(vii) Cultural method: This involves the use of cultural practices of crop production to reduce the growth of weeds on the farm. Such cultural practices include
i. Burning of farmland: This kills weed parts, seeds and fruits both in the soil and on the surface.
ii. Tillage: Tillage helps to expose weed parts for destruction by sun or herbicides. They can also be hand picked and destroyed.
iii. Early planting: This ensures that crops are well established before the weeds start growing.
iv. Good spacing: Proper spacing of crops helps in the reduction of weeds along the crop rows. It also makes it easy for weeding to he done.
v. Mixed cropping: Planting or two or more crops, together oil the same farmland can help to reduce the intensity of weeds on the farm
(c) Biological method
This involves the use of living plants and animals to control weeds. They include:
(i) Use of suppressive plants: Crops that grow fast and large too can be used to overshadow weeds thereby reducing their growth, Also, cover crops such as melon and legumes like groundnut can be used to control weeds on the farm.
(ii) Use of insects: This involves the use of identified insect pests weeds in controlling weeds on the farm. Insects which have been found to feed on a particular weed can be multiplied and introduced to the area to feed and destroy such weed species.
(iii) Pasturing: This involves the grazing of farm animals on weeds usually in plantations such as rubber and oil palm. Animals like i cattle, sheep or goat are commonly used in this method.
(d) Chemical method
This is the method that is used on a large scale. It makes use of chemicals in the control of weeds. These chemicals are known as herbicides. They are sprayed either on the leaves of weeds or applied to the soil. They are classified into:
(i) Selective herbicides: These are chemicals that can kill certain groups or species of plants. Example is 2, 4 -D (Dichlorophen-oxyacetic acid). They can be used in cereals, sugar cane and soya beans farms to reduce weeds.
(ii) Non-selective herbicides: These arelthe herbicides that can kill any plant which they come in contact with. Examples are arsenicals chlorates, petroleum oils and carbon disulphide.
Herbicides can also be classified as contact herbicides, systemic or translocation herbicides.
The contact herbicides are applied as foliage sprays (that is on the leaves), dust or granules: They scotch the tissues of the plants already growing on the farm. Examples are sodium chlorate and arsertates.
The systemic or in trans-located herbicides are carried in the tissues of the plants after the ingredients have been absorbed by the roots in the soil. These chemicals must first enter the soil and then absorbed the roots of the weeds into their tissues. They are applied as dust or granules onto the plants or used as soil treatments. When used as soil treatments, they control all weeds that are still to emerge from the soil, hence, they are sometimes called pre-lltrgencc herbicides. Examples are 2,4,5-T(2,4,5-Trichlorophen-oxyyacetic acid), Atrazine and others.

Quality of good herbicide


A good herbicide recommended for use should have the flowing qualities:
1. It should be able to kill the weeds easily and at a small dosage rate. That is, it should be phytotoxic.
2. It should kill the weeds and not the growing crops. That is, it should be selective in its action.
3. It should have low toxicity on animals that use weeds as food and on man.
4. It should be easy to compound or formulate.
5. It should be easy to use.
6. It should be cheap and easy to get.

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You can read some of most interesting topics below
Agricultural biology topics


HERE YOU WILL FIND EVERY AVAILABLE TOPICS ABOUT AGRICULTURAL SCIENCE AND BIOLOGY. AND THE LINKS TO THEIR VARIOUS SOURCES.
1. DEVELOPMENT OF AGRICULTURE
2. IMPORTANCE OF AGRICULTURE
3. SUBSISTENCE AGRICULTURE
4. COMMERCIAL AGRICULTURE
5. PROBLEM OF AGRICULTURAL DEVELOPMENT
6. SOLUTIONS TO POOR AGRICULTURAL DEVELOPMENT
7. AGRICULTURAL LAWS AND REFORMS
8. ROLES OF GOVERNMENT IN AGRICULTURAL DEVELOPMENT
9. AGRICULTURAL POLICIES
10. PROGRAM PLANNING IN AGRICULTURE
34.
FORESTRY
35. WILDLIFE CONSERVATION
36. FACTORS AFFECTING LAND AVAILABILITY
37. TOPOGRAPHY
38. SOIL
39. BIOLOGICAL FACTORS
40. SOCIAL-ECONOMIC FACTORS
41. ENVIRONMENTAL FACTORS AFFECTING AGRICULTURAL PRODUCTION
42. CLIMATIC FACTORS AFFECTING AGRICULTURAL PRODUCTION
43. TEMPERATURE
44. RAINFALL
45. WIND
46. SUNLIGHT
47. SOLAR RADIATION
48. BIOTIC FACTOR AND AGRICULTURAL PRODUCTION
49. PESTS
50. BIRDS
51. DISEASES
52. SOIL MICRO-ORGANISMS
53. SOIL PH
54. ROCK FORMATION
55. IGNEOUS ROCK
56. SEDIMENTARY ROCKS
57. METAMORPHIC
58. SOIL AND ITS FORMATION
59. FACTORS OF SOIL FORMATION
60. LIVING ORGANISM
61. PARENT MATERIALS
62. SOIL FORMATION TOPOGRAPHY
63. PROCESS OF SOIL FORMATION
64. WEATHERING
65. PHYSICAL WEATHERING
66. CHEMICAL WEATHERING
67. PRESSURE
68. WATER
73. BIOLOGICAL WEATHERING
74. CHEMICAL AND BIOLOGICAL COMPOSITION OF THE SOIL
75. SOIL WATER
76. MICRO AND MACRO NUTRIENTS
77. SOIL MICRO ORGANISM
78. PROPERTIES OF SOIL
79. SOIL STRUCTURE
80. SANDY SOIL
81. CLAY SOIL
82. LOAMY SOIL

83. SOIL TEXTURE
84. IDENTIFICATION OF SOIL TYPES THROUGH EXPERIMENTS
85. RETENTION OF WATER BY VARIOUS SOIL TYPES
86. DETERMINATION OF SOIL PH REACTION
87. COLORIMETRIC DETERMINATION OF SOIL PH LEVEL
88. PH SOIL TEST
89. PLANT NUTRIENTS
90.
MACRO NUTRIENTS IN GENERAL
112.
THE MAINTENANCE OF SOIL FERTILITY
113. CROP ROTATION
114. APPLICATION OF ORGANIC MANURES
115. FARM YARD MANURE
116. APPLICATION OF INORGANIC MANURE

117. LIMING
118. FARMING PRACTICES
119. BUSH BURNING
120. CLEARING

121. FERTILIZER APPLICATION
122. ORGANIC MANURING
123. FARM YARD MANURE

124. HUMUS
125. COMPOST
126. CROP ROTATION
133. FARM POWER AND MACHINERY
134. SOURCES OF FARM POWER
135. HUMAN SOURCE
149.
PLOUGHS
142.
FIELD MACHINES
157.
PLANTERS
164.
SIMPLE FARM TOOLS
165. AGRICULTURAL MECHANIZATION
166. THE CONCEPT OF MECHANIZATION

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