What are selective herbicides?

When the good weather and the spring rains have arrived, all kinds of weeds begin to appear vigorously in our fields. Weeds create competition and harm our cultivation and the quality of the harvest. For this reason, spring is also synonymous with looking for herbicides to control weeds.

There are several types of herbicides. Today we are going to talk about selective herbicides . We will see what they are, how they work, how effective they are and their main advantages and disadvantages. 

What are selective herbicides?

Cereal field with weeds

Contents [ hide ]

  • 1 What are selective herbicides?
  • 2 How do selective herbicides work?
    • 2.1 Broadleaf herbicides
    • 2.2 Narrow-leaf herbicides
  • 3 What is the effectiveness of selective herbicides?
    • 3.1 Herbicide applications
    • 3.2 Selectivity
    • 3.3 Mortality
  • 4 Advantages and disadvantages of selective herbicides
  • 5 How can I keep track of herbicide treatments and my farm?

What are selective herbicides?

Selective herbicides are herbicides that are used to control and kill weeds that grow in fields without damaging the main crop . In this way we can control weeds based on the species and its category. 

How do selective herbicides work?

Selective herbicides are applied directly to the field and are quickly absorbed by weed leaves . Once it has been absorbed, it penetrates the branches, stems and roots of the weeds. Depending on the composition of the herbicide, weeds behave differently. Generally, selective herbicides affect the vascular system of plants, blocking their growth and eliminating them after a few days.   

How do selective herbicides work?

clean field of weeds

Depending on the weed we want to eliminate, we will use selective herbicides for broadleaf or narrowleaf . This category is used to classify the botanical species that can appear more frequently in our cultivation.

Broadleaf herbicides

They are applied during the fall and spring, depending on the crops and the weeds that start to grow. 

Narrow-leaf herbicides

They are applied during the spring and fall and must be applied more than once during the application period. 

It should be said that a selective herbicide at very high doses can be a total herbicide , that is, it completely kills any plant , including the main crop. This is why the manufacturer’s and our technical advisor’s instructions should always be followed. 

What is the effectiveness of selective herbicides?

To know the effectiveness of selective herbicides it is important to take into account 3 parameters:

Herbicide applications

As we discussed earlier, there are selective herbicides that require a single application and others that require more than one . This depends on the herbicide we use and the weed to combat. 

herbicide application

herbicide application


The herbicide must be selective and include some protector for the most common winter cereals or the crops that we have established. In this way we ensure that it does not damage the main crop . 


The action of the selective herbicide must be fast and during the first 24-48 hours it must stop the growth of the weeds that we are fighting. After a few days we should see the first symptoms in the weeds: chlorosis and necrosis in the tissue (dehydration and drying of the plant). Although the plants take a few weeks to be eliminated, stopping their growth is crucial so that they are not competition for the main crop. 

Weeds after a herbicide application.

Weeds after a herbicide application. 

Advantages and disadvantages of selective herbicides

Selective herbicides are of great help to control weeds in our crops. As we have said, weeds can generate very high competition with our crop, deteriorating it if they are very vigorous. Let’s look at the main advantages and disadvantages of selective herbicides. 

Protection of the main crop : as it is a selective herbicide, the main crop is not damaged and we make sure that it can grow without problems to maximize its yields. 

Elimination of competition : weeds produce significant competition to the crop and can cause considerable damage. In addition, to sell the grain, a clean grain of other grains that are not of the crop is rewarded. By applying the selective herbicide at the right time we eliminate weeds and their problems. 

Field with a great competition of poppies.

Field with a great competition of poppies. 

Application time : selective herbicides allow us to apply both in early growth stages and in the middle. 

Adverse weather conditions: as selective herbicides act quickly on weeds, they allow us to make applications without depending on temperature, humidity or rainfall. 

Resistance: the main drawback of selective and non-selective herbicides is the resistance of weeds. That is, a continued abuse of a herbicide over time on a weed species can develop herbicide resistant weeds. 

Plant diversity: the specific component (wide leaves or narrow leaves) of herbicides means that if we have a field with a diversity of weeds, the applications that we will have to make will be multiple and more expensive. 

How can I keep track of herbicide treatments and my farm?

Increasingly, farms diversify their crops and this implies greater attention to herbicide and fungal treatments , planting calendars, harvests, yields, expenses, field notebooks, etc.

With Agroptima, it is now possible to carry out the comprehensive management of your farm with your mobile phone in an easy and simple way. With Agroptima you can write down the tasks and treatments , make the field notebook in one click, have a report of expenses and benefits … and all this on the tractor with your mobile phone . Now you can try Agroptima for free for 15 days here .

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