Mechanical /Physical Weed

Control

Some basic principles of mechanical weed control

• In-row weeding is essential! • Cultivator rows = planter rows (or some nice

fraction)– Exceptions – tine weeders & rotary hoes

• Cultivator must be appropriate for the growth stage of the weeds and crop

• Create and maintain a size difference between weeds and crop

More principles

• When weeds are very dense, cultivators take out a smaller fraction of them

• Increase planting density to compensate for stand loss from in-row machines– Especially in small grains

• Good soil drainage helps a lot!• Chop crop residue if you reduce tillage• Create a dust mulch

Mechanical Weed Control

Mechanical or physical methods of weed control are being employed ever since man began to grow crops. The mechanical methods include tillage, hoeing, hand weeding, digging cheeling, sickling, mowing, burning, flooding, mulching etc

1.Tillage: Tillage removes weeds from the soil resulting in their death. It may weaken plants through injury of root and stem pruning, reducing their competitiveness or regenerative capacity.

2. Hoeing: Hoe has been the most appropriate and widely used weeding tool for centuries. It is however, still a very useful implement to obtain results effectively and cheaply.

3. Hand weeding: It is done by physical removal or pulling out of weeds by hand or removal by implements

called khurpi, wPulling methods uproot and remove the weed from the soil. Weed pulling can be used to control some shrubs, tree saplings, andherbaceous plants. Annuals and tap-rooted weeds tend to be very susceptible to pulling. Many species are able to re-sprout from root segments that are left in the soil. Therefore, the effectiveness of this method is dependent on the removal of as much of the root system as possible. Well established perennial weeds are much less effectively controlled because of the difficulty of removing all of the root system and perennating plant parts. Small herbaceous weeds may be pulled by hand but larger plants may require the use of puller tools like the Weed Wrench or the Root Talon. This technique has a little to no impact on neighboring, non-target plants and has a minimal effect on the growing environment. However, pulling is labor intensive and time consuming making it a more suitable method to use for small weed infestations.

hich resembles sickle.

4. Digging: Digging is very useful in the case of perennial weeds to remove the underground propagating parts of weeds from the deeper layer of the soil.

5. Sickling and mowing: Sickling is also done by hand with the help of sickle to remove the top growth of weeds to prevent seed production and to starve the undergroundMowing methods cut or shred the above ground of the weed and can prevent and reduce seed populations as well as restrict the growth of weeds. Mowing can be a very successful control method for many annual weeds. Mowing is the most effective when it is performed before the weeds are able to set seed because it can reduce the number of flower stalks and prevent the spread of more seed. However, the biology of the weed must be considered before mowing. Some weed species may sprout with increased vigor after being mowed

6.Flooding:

Flooding kills plants by reducing oxygen availability for plant growth. The success of flooding depends upon complete submergence of weeds for longer periods.

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7. MulchingThe principle of mulching is to exclude light from the tops of the weeds until the reserve food supply in the roots is depleted and the weeds starve. Mulches include clean straw, hay or manure, tar paper, sawdust and black plastic. Black plastic is very effective. When the vegetation under the mulch has been destroyed, the resultant bare patch must be reseeded with competitive vegetation to prevent new weed introductions.

8. Spring tillage. Start with a weed-free seed bed. There are many tillage tool options used successfully by organic farmers. Do not overlook that moldboard plowing tends to bury weed seed and plant residues giving a little bit of an advantage.

9. Post-emerge tillage. Be ready with a variety of tools. The first cultivation might be the most important. The weeder and rotary hoe can be used with care after the crop has emerged. Flamers can be used pre- and early post, but skill and know-how is critical. Cutaway disks, weed controllers, spinners, shields, etc., are all special attachments that can aid in weed control effectiveness. Farmer ingenuity is at work with double frame rotary hoes, direct steering on cultivators, specialized attachments and precise timing. Correct speed, proper adjustment, good maintenance, operator skill and good weather make a huge difference in the weed control success.

10. Soil structure. Soil compaction reduces crop vigor and tends to promote curtain small seeded weeds. Be patient. Do not work wet soil.

11. Soil health. A balanced healthy soil will produce a healthy crop with the ability to compete with weed pressures

12. Root TalonThe Root Talon is an inexpensive and lightweight tool shaped something like a pick-ax with a plastic handle and metal head. It has a specialized claw and gripping device that allow the user to grab the plant stem and provide leverage to pull-up and remove the plants. It is best used for pulling shallow rooted plants such as sapling trees and herbs with sturdy stems. Plants that have been pulled using the Root Talon include young tree-of-heaven (Ailanthus), Scarlet wisteria (Sesbania punicea), and buckthorn (Rhamnus spp.).

13. The Weed Wrench can be used on herbaceous plants that have a stem or bundle of stems strong enough to withstand the crush of the jaws. It has been used successfully to pull acacia (Acacia melanoxylon), buckthorn (Rhamnus cathartica), Russian olive (Elaeagnus angustifolia), multiflora rose (Rosa multiflora), willow (Salix spp.), tamarisk (Tamarix spp.), bush honeysuckles (Lonicera spp.), Scotch broom (Cytisus scoparius), French broom (Genista monspessulanus)

14. GIRDLINGGirdling is often used to control trees or shrubs that have a single trunk. It involves cutting away a strip of bark several centimeters wide all the way around the trunk. The removed strip must be cut deep enough into the trunk to remove the vascular cambium, or inner bark, the thin layer of living tissue that moves sugars and other carbohydrates between areas of production (leaves), storage (roots), and growing points. This inner cambium layer also produces all new wood and bark.

15 Cutting ;-Weeds are cut above the ground surface leaving stubble. It is most common practice against brush and trees.Cutting is done with the help of axes and saws.

16. Dredging and Chaining :-Dredging and chaining methods are used to control aquatic weeds.Removing of weeds along with their roots and rhizomes with the help of mechanical force is called dredging.The floating aquatic weeds are removed by chaining.A very heavy chain is pulled over the water bodies to collect the weeds.

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17. Hand hoeing :-The entire surface soil is dug to a shallow depth with the help of hand hoes, weeds are uprooted and removed. After hand hoeing, the field is subjected to drying to avoid re-establishing of uprooted weeds. This method is adopted in irrigated upland crops like finger millet, pearl millet, onion etc.

18. Burning and Flaming :-Burning is the cheapest method of eliminating mature unwanted vegetation from uncropped areas like range lands, field bunds, roadsides, ditch banks etc.It is also used to dispose off heaped weeds. However, it is a 'potential source of fire hazard.

19. Chop:If digging out weeds is difficult for you, at least resolve to keep them from setting seed. Chop off their heads once a week!

20. Trim:Keep the edges of your garden mowed; this will help prevent a weed invasion.

21. Close Ranks:If your soil is rich and well tilled, plant your plants closer together. This will cut down weed growth.Start your warm weather plants as soon as you can, to keep the soil from being bare for too long. At the end of the season, plant cover crops such as rye grass, winter wheat, or oats to prevent weeds from finding a home in your garden.

22. Cut Them Off at the Pass:-Encourage weeds to grow before you plant your garden. Lay sheets of clear plastic over your garden in early spring to warm up the soil and encourage weeds to germinate. Once the weeds are several inches above the soil, pull or hoe them out. Then plant your own crops.

23. Use Drip Irrigation:If you can irrigate only the plants that need it, you may avoid the cultivation of weeds in unplanted areas, paths, and areas where they are not welcome.

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24. Eat Your Weeds!Yes, some weeds—lamb’s quarters, amaranth, purslane and others—are edible when young and tender. See our post, "Eating Weeds: Why Not?“

25. Crowning: This technique is useful for weeds such as asparagus fern, which have their growing points below the surface of the soil. (corms, rhizomes or tufted fibrous root systems).Grasp the leaves or stems of the plant and hold them firmly so that the base of the plant is visible. Any weeds with sharp leaves or stems should be cut back first.Insert a knife close to the base of the plant at an angle, with the tip well under the root system.Cut through the roots close to the base of the plant. Make sure that the hard crown or base of the plant where the roots begin is completely removed. It may require several cuts.Hang the crowned plant matter up off the ground.Follow up on a regular basis.

26.FireBurning and flaming can be economical and practical methods of weed control if used carefully. For most plants, fire causes the cell walls to rupture when they reach a temperature of 45°C to 55°C.Burning is commonly used to control weeds in forests, ditches, and roadsides.Burning can be used to remove accumulated vegetation by destroying the dry, matured plant matter as well as killing the green new growth

27. Soil SolarizationSoil solarization is a simple method of weed control that is accomplished by covering the soil with a layer of clear or black plastic. The plastic that is covering the ground traps heat energy from the sun and raises the temperature of the soil.Many weed seeds and vegetative propagules are not able to withstand the temperatures and are killed. For this method to be most effective, it should be implemented during the summer months and the soil should be mois

Merits of Mechanical Method 1) Oldest, effective and economical method 2) Large area can be covered in shorter time 3) Safe method for environment 4) Does not involve any skill 5) Weeding is possible in between plants6) Deep rooted weeds can be controlled effectively

Demerits of Mechanical Method 1) Labour consuming 2) Possibility of damaging crop 3) Requires ideal and optimum specific condition

Mechanical weeders

Dry Land Weeder

Power rotary weeder

Tractor drawn weeding cum earthingup equipment

Tractor operated multi row rotary weeder

Cono weeder