Natural weed killers are the different natural agents which are used in killing or controlling the weeds without affecting the nature or environment. These can be different bacteria, fungi or other microorganisms, plants, animals or insects which kill or suppress the weeds due to the action of feeding or living on the weed plants. The natural weed killers are very much nature friendly and takes the crop production programs towards the sustainable sides. These will also be helpful in reducing the initial cost of cultivation of crop production by reducing the cost of weed control operations as these are of very much economic side.
The different natural weed killers are discussed in detail below:
- Beetles: The two beetles namely, Octotoma scabripennsis & Uroplata giraldi are used for the control of weed Lantana camara which is a very problematic weed of many countries these days. These beetles would feed & live upon the lantana species & do not allow it to flourish or develop due to the parasitic action on it.
- Common fishes: The certain species of fish like common carp fish & the Chinese carp fish are also a great means of natural weed controllers of weed species like alternanthera philoxeroids etc. Once these fish were introduced in the water bodies like lakes, rivers, ponds, wells & rice fields these will kill the weed species by feeding upon them & thus control them very well by natural means.
- Scale insects: The scale insect is a very good natural controller of the weed species like Opuntia or prickly pear weed. The scale insect will control the opuntia weed by using it as a host plant & completes their life cycle on it by & as a result controls its growth & development.
- Sea cow: The aquatic weed species of Water-hyacinth is controlled or fully removed by the sea cows which use them as food and completely make the water body free of water hyacinth in a week or so.
- Different mites: The different species of mites will also act as very good natural weed killers or natural weed controllers as these will also act as parasites on weeds & fulfill their life cycle on these weeds. Certain weeds controlled by mites are prickle pear, lantana etc.
- Use of plants: The use of pulses as intercrops or mixed crops in between the main cereal crops is also an important means of natural weed control. The pulse crops will do not allow the weed species to grow or develop as they will take away the empty space of the field on which weed grows and in this way they act as natural weed killers. For example, the sowing of cowpea in between the rows of sorghum crop will protect the sorghum crop from many harmful weeds like Striga sp., Dactyloctaneum aegypticum etc. which will otherwise will deprive the yields of sorghum crop.
- Different weed eating fungi: The fungi species like Rhizoctinia, Aspergillus etc. are a good means of natural weed control as these will kill the weeds without the use of any harmful chemical of synthetic means. The fungi are the fastest as well as economical means of weed control and do not let them interfere with the crop production programs or in different water bodies. The best example is of control of various aquatic weeds by fungi.
- Snails: The different snails will also a good means of natural weed killing as these will feed on the weeds which are having thin stem and good leafy structures. Snails will also control or manage the submerged weeds like coontail & their other harmful species.
The different examples of natural weed killers are presented below in table: