Farmers and agriculturalists often note that the use of the same herbicide for several seasons becomes inactive against the targeted weed species and soon it is judged that this herbicide has become ineffective. The real reason behind this is increasing the growth and reproduction of weed species that can survive which is technically known as (Weed Resistance).

 The phenomenon of weed resistance to herbicides is the most important problem facing weed chemical control which is considered as the ability of a certain genotype belonging to one of the weed species to survive, while the other genotypes of the same weed species are affected.

The weed resistance does not mean the poor performance of the used herbicide as much the difference in the genetic diversity, which allows some of the genotypes to survive and produce new generations while the other genotypes are killed. These resistant genotypes often survive even if the herbicide is used in a higher dose than the recommended dose.

On the other hand, herbicides are different in terms of the controlling mechanism to weed, so the weed resistant species can be resistant to other herbicides which used the same controlling mechanism.

Currently, there are more than 249 weed species that are resistant to herbicides over the world which are distributed in 47 countries according to the latest reports. These numbers increase annually with the development of new resistance.

Strategies of reducing the development of weed resistance to herbicides include several things which are:

1- Applying the principle of Integrated Weed Management

IWM is known as the technic of using more than one method to reduce weed competition using alternative methods to act with or without herbicides such as planting varieties that are characterized by their high competitive to weed or crop rotation.

-2  Herbicides Mixture

Resistant genotypes to one of the killing mechanisms are sensitive to another one. Thus, reducing the weed population per unit area and reducing the chances of its growing and producing new generations.

3- Use the alternation principle of herbicide groups

This principle provides an opportunity for herbicides to target as many types of weed as possible, especially in fields and orchards that grow in different economical plants species due to the similar conditions and growth requirements with weeds.

4-Using herbicides at the recommended dose

As mentioned previously, resistant weed species remain resistant to the herbicide even if it is used in recommended doses. So there is no point in using a dose higher than the recommended

5-Try to reduce using herbicides.

As well known, the use of herbicides is a double-edged sword, so we cannot imagine that we can achieve a balance in agricultural production to provide adequate food for all the world’s population which witnessed an unexpected acceleration in recent decades without using Herbicides. At the same time, there is an urgent need to reduce the use of Herbicides due to their negative impact on the environment and humans.