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Why weed management?
Weed is an unwanted plant that grows in fields and interferes with agricultural operations and reduces crop yield. It gives competition to the main crop for space, nutrients, light, moisture, etc. In some cases, yield loss due to weed is up to 80%. That is why it becomes very important to manage the weed population in the field.
Losses caused due to weeds
Increase in cost cultivation
During crop production, 30% of the expenditure is incurred on tillage operation which is mainly done to remove weeds.
Reduction in the quality of crop produce
Infestation of weeds deteriorates the quality of crops. The quality of leafy vegetables are highly affected by the presence of weeds.
Harbouring pest and diseases
Weeds become an alternative host for pests and diseases. Example- Mustard weed act as an alternative host for cabbage root maggot in cabbage cultivation.
Smothering the growth of crop
Weeds decrease the availability of nutrients for the main crop which is required for proper growth and development due to which crop growth declines.
Interfering with agricultural operation
The presence of Weeds in the field create problems during tillage operation, earthing, preparation of bed, etc.
Harmful secretion by some weeds is very harmful to the main crop. For example- secretion from roots of nutgrass reduces the germination rate of seed, causing great loss in terms of yield.
Preventive measures
Weed - free clean seed should be selected for sowing. Seeds that are contaminated with the seeds of weed can spread weeds. Loose packet seeds which are sold in the market have weed seeds.
The spread of weeds can be controlled by using clean agricultural implements like cultivators, seed drills, etc. Sometimes after performing agricultural operations these implements carry some part of weed that can be propagated into the field where the implement will be used next.
Remove the weeds which are grown along the canal and irrigation channel.
Follow proper crop management practices like- Proper crop rotation prevents the growth of weed, more plant population per unit decreases the population of weed, proper method of fertilizer application so that nutrients can be obtained only to the main crop, etc.
Use pre emergence herbicides before or after planting the crop. Application of herbicide deprive the seed germination of weeds
Use well rotten manure because it could contain seeds of weed and if the heating period will be short, seeds would not lose their viability and will germinate.
Proper care and management should be taken during the transplanting of plantlets. A small amount of soil is attached to the plantlet during transplanting, this soil could carry seeds of weeds.
Curative methods
Physical method
In this method, weed is controlled by hand weeding, digging, flooding, mulching, hoeing etc. Tillage operations remove weeds from the land. In the row, cropping hoeing is widely practiced. Khurpi can be used to pull out weeds from the field. Nowadays, mulching is becoming popular, in which mulches of straws 10 to 15 cm thick inhibits the top growth of weeds.Cultural method
In this method, agronomical practices are done in such a way that the population of weed is reduced.
Proper selection of crop is necessary, crop must grow fast leaving weed behind.
Roots of Crop should absorb nutrients from the top as well as lower regions of soil.
Crop must have dense canopy
Proper crop rotation should be followed.
Compost in the organic matter should be added to the field, Because during the decomposition of compost uric acid is produced which prevents weed growth.
Irrigation can be given before sowing so that seeds of weed could germinate and can be removed at the time of ploughing.
Land should be kept fallow for some time.
Biological method
Some plants act as bioagents to control weeds. Fast-growing plants have an advantage over slow-growing plants.
More plant population favors less weed growth
Some parasites, predators and pathogens can be used to kill the weeds
Chemical method
Now a days use of weedicide or herbicide has been increased drastically because it has following advantages-
Chemicals can be used at the place where harrowing is not possible
Herbicides have quicker response
Labor requirement is reduced due to the use of herbicides.
Generally, hand weeding injures the root of the main crop, herbicides do not.
Time And rate of application of some common herbicides
Atrazine (Pre,ppi, early post) 1-3kg/ha
Dinitramine (Ppi): 0.5-1.5kg/ha
Diquat (Post): 1-4kg/ha
Diuron (Pre, early post): 0.5-3.0kg/ha
Fenuron (Pre): 2-6kg/ha
Dalaphon (Post): 2-5 kg/ha
Pendamethalin (Pre, ppi): 1-2kg/ha
Fluchloralin (Pre,ppi): 1-3kg/ha
Weed Management by Ancient methods (ITK)
Tribal people followed the godai method in which they used khurpi to remove the weeds from the field.
During summer and after rabi, deep ploughing exposes weed seeds to the sun and destroys them.
Application of neem seeds at the rate of 40 kg/ac as basal helps in weed growth.
Arugu weed is controlled by keeping land Fallow for 3 years, cultivating rice once in three years.
Horse gram and cowpea can be used to control nutgrass weed.
Swine can also be used to eradicate nut grass in the field.
50 kg of neem cake is used at the time of ploughing and sowing to control nutgrass
All the grasses except nutgrass can be controlled by a solution made by dissolving 1 kg of salt and 100 g of Sarvodaya soap in 10 litres of water.
Congress weed can be eradicated by spraying a solution made from 200 grams of salt in 1 liter of water.
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