Herbicides Important Topics

 Herbicides :- 

Chemical method of meet control is very effective in certain cases and use great score provided the herbicides are cheap efficient and easily available. 

The chemical used for killing weeds or inhibiting the growth of weights are called herbicides

Classification of Herbicides :- 

 Based on Method of application :- 

i) Soil applied herbicides: Herbicide act through root and other underground parts of weeds.e.g. Fluchloralin

ii) Foliage applied herbicides: Herbicide primarily active on the plant foliage e.g.Glyphosate, Paraquat.

Based on Mode of action :- 

i) Selective herbicide: A herbicide is considered as selective when in a mixed growth of plant species, it kills some species without injuring the others.e.g. Atrazine

ii) Non-selective herbicide: It destroys majority of treated vegetatione.g. Paraquat

Based on mobility :- 

i) Contact herbicide: A contact herbicide kills those plant parts with which it comes in direct contact e.g. Paraquat

ii) Translocated herbicide/Systemic Herbicide: Herbicide which tends to move from treated part to untreated areas through xylem / phloem tissues depending on the nature of its molecule. e.g. Glyphosate

GroveStudies 

Based on Time of application :- 

i) Pre - plant application: Application of herbicides before the crop is planted or sown.

ii) Pre – emergence

Application of herbicides before a crop or weed has emerged.

iii) Post – emergence

Herbicide application after the emergence of crop or weed is referred as post-emergence application.

Based on molecular structure:

Inorganic compounds

Organic compounds

Important definitions in herbicides :- 

1 selective herbicides:- 

the chemical which kills or retards the growth of some plants with little or no injury to other plants.

2. Non Selective Herbicides :- 

These chemicals are toxic to all the plants or kill all kinds of vegetation.

3. Contact herbicides :- 

 herbicide which kills only those plants or retards the growth of those plants which comes in direct contact.

4. Translocated herbicides :-

 the Herbicides at which are absorbed by the one part of plants and exert a toxic action to the other plants.

These are also known as systematic Herbicides.

Advantages of herbicides or chemical method of weeds control :-

They kill unwanted plants

 They are easy to use.

Herbicides can be used on closely planted crops where other methods cannot be used.

Most of the time one application of herbicide is enough whereas other methods have to be continuously used.

They work fast. Can be removed quickly in critical situation.

Herbicides are relatively cheap and most of the time cheaper than manual weeding.

Disadvantage of Herbicides :- 

Some herbicides are non biodegradable and are harmful for long period of time.

Heavy dose of herbicides affect microbial population of the soil.

Most of the service ads are specifically plant poisonous and are toxic to animals.

Pesticides and herbicides can cause a number of health problems such as kidney damage, low blood pressure, muscle damage weight loss etc.