Agriculture Reference
In-Depth Information
Herbicides have provided a more effective and economical means of weed
control than mechanical cultivation. Together with fertilizers and improved
varieties of plants, herbicides have made a immense contribution to increased
yields and reduced costs.
A.
CLASSIFICATION OF HERBICIDES
Every type of herbicide classification has overlap and this is true espe-
cially when the assignment is made according to the type of use and mode of
action. It is possible to differentiate herbicides by the following parameters:
In timing of application and sowing or planting time of the plants grown:
•
pre-sowing
•
preemergence
•
postemergence herbicides.
The uptake area:
•
soil herbicides
•
leaf herbicides.
The mode of action:
•
contact herbicides
•
systemic herbicides.
The range of use:
•
non-selective herbicides
•
selective herbicides.
In this section, we emphasize the use of chemical classification of herbi-
cides. The two major classifications are inorganic and organic herbicides.
1.
Inorganic Herbicides
As we mentioned earlier in Chapter 1, the first chemicals used in weed con-
trol were the inorganics. Until the 1960s arsenic-containing compounds were
commonly used and therefore we will start with them.
a.
Organic and Inorganic Arsenical Compounds
1.
Inorganic Pentavalent
