Weed management requires an integrated strategy rather than single approaches and it starts at the time of land preparation. In any crop production practice, weed control is limited to five options i.e. preventative, cultural, biological, mechanical, and chemical control. Choice of a particular method or methods depends upon the weed spectrum, crop rotation sequence, and other factors.
Preventive weed control: These are practices that will limit introduction or spread of weeds in the field. These include:
- Planting clean, weed-free finger millet seed.
- Ensuring that all equipment used to plant finger millet is free of weed seeds.
- Controlling weeds along ditch banks, roadsides, and field margins to prevent weed seed from entering fields.
Cultural weed control method: These are practices that allow the crop to become established without experiencing any negative effects of weed interference. These include:
Proper crop variety selection: Different genotypes of the same crop possess different traits that make them vary in their abilities to compete against weeds. These traits are typically those related to faster seedling emergence, quick canopy establishment and higher growth rates in the early stages. Use of these genotypes can therefore reduce the need for direct weed control measures (e.g. herbicides or cultivation)
Timely planting: This will ensure that crop emerge first giving it a competitive advantage for resources against the weed
Plant density: A good crop cover by adopting right spacing between rows and within the row will smother weed growth. Sowing finger millet by drilling eliminates spaces where weeds can grow within the plant row. The only available space for weed growth is between the rows where weeds can be removed by hand hoe in small farms.
Intercropping: Intercropping increases the use of natural resources by the canopy and, compared to sole crops, often compete better with weeds for light, water and nutrients. For example, compared to sole cropping, a finger millet cowpea intercrop sown in a two row-by-one row layout decreased relative soil cover of weeds.
Crop rotation: This is a practice of growing different crops in a sequence. When different crops are grown, different cultural practices are used and as such, cuts the life cycle of weeds.
Mechanical /Physical weed control: In the physical weed control method, weeds are removed from the field or are frequently disturbed to cause their death or inability to produce seed. There are several ways this can be done and these include;
- Turning the soil well during cultivation so as to cover all weeds to deny them re-growth.
- Slashing down all weeds so as to deplete their food reserves and cause their death. This can be done between the finger millet rows.
- Removing weeds by hand especially those growing very near the crop plants. This is possible where there is spot growth of weeds and is common for finger millet.
- Using of hand hoe, which is a very common practice by resource poor farmers. It is the best way of removing weeds between the rows of finger millet. Any weeds found within the rows are removed by hand.
Chemical weed control: Chemical control or herbicide application is advantageous in case of non-availability of labour and/or very high cost of labour for manual weeding. Use of correct herbicides will provide a completely weed-free situation to the crop whereas manual or mechanical weeding can be practiced only after the emergence of weeds. However, chemical weed control options are limited for finger millet production. Use of chemicals (herbicides) to control weeds should be based on their cost effectiveness compared to cultural and mechanical control measures. Herbicide application requires some knowledge about the use of such chemicals.
Source: NARO handbook on millet