The Principles of Weed Control Area as Under
1) Habit of Weed Plants:
Xerophytic weeds thriving under dry and arid conditions will die if the field is flooded with water.
The weeds which thrive under marshy and ill drained soil condition can be controlled by improving drainage.
2) Life Cycle of the Weed:
Annual Weeds can be controlled effectively if they are destroyed before formation of lowers and seeds by using mechanical or chemical methods.
Biennial weeds can be controlled by proper tillage like deep ploughing in the first season when they have only vegetative growth and before the formation of flowers.
Perennial Weeds can be controlled by deep ploughing and exposing their vegetative parts to heat of the sun, collection and destruction of vegetative plant parts or by suitable combination of mechanical and chemical methods.
3) Susceptibilities of Weeds to Control Herbicides:
Some weeds are suitable to certain herbicides while others are not e .g dicot weeds are susceptible to 2,4-D while monocots are not susceptible. Therefore, 2,4-D is is used to control the dicot weeds in cereal crops and sugarcane.
Glyphosate is non- selective herbicides and used to control dicot as well as monocot weeds in non-cropped areas or as directed spray in fruit crops and wide spaced crops like sugarcane.
4) Dormancy Period:
The seeds of weed species belong to family convolvulaceae, Gramineae, Leguminaceae etc have long dormancy. Therefore, dormancy period of weeds. Such weeds should be destroyed before flowering to avoid seedling in the field. Such weeds also require repeated Interculturing or spraying of herbicides for their control.
5) Resistance to Adverse Conditions without Losing Viability:
Some weed seeds have hard seed coat and remain viable for long time even buried deep in the soil. Such weeds should be destroyed before flowering and seedling.
6) Method of Reproduction:
By seed can be controlled by suitable mechanical methods or chemical methods before flowering and seedling.
Vegetatively can be controlled by deep ploughing and exposing under ground part to heart of the sun. collection and destruction of vegetative plant parts or by using translocated herbicides.
By Seeds and Vegetatively:
Controlled by suitable combination of mechanical methods like deep ploughing and use of translocated herbicides.
6) Dispersal of Weed Seeds:
Weeds can be controlled by taking into account the mechanism of dispersal of weed seeds. Suitable measures should be adopted for avoiding further spread of weeds by different agencies.
7) Area of Weed Management:
Small Area: Mechanical method i.e hand weeding.
Medium Size Holding: Mechanical methods or chemical methods of 2 to 5 ha.
Larger Areas: Chemical methods or integrated weed management.
9) Resources Availability:
Farm labour, implements, machinery and herbicides are the major inputs in weed management. The availability and cheapness of these inputs determine the method of weed management.
10) Farming Cultural Practices:
Selection of suitable method of weed management depends upon the type of farming and cropping system. Cultural practices like proper land preparation, timely sowing, maintaining optimum plant population, better irrigation, fertilizer management and plant protection help to manage the weed.