Weed: Any plant growing out of place is a weed.
- It competes with the fruit trees for water and nutrients.
- Weeds sometimes act as intermediate or alternate hosts to certain pests, diseases which cause heavy losses to the main crop.
- The weeds may be crop specific or season specific i.e. annual, biennial and perennial weeds.
- In India, yield loss due to weeds is approximately 33 per cent of total production, and on an average 30 per cent of the total production cost is spent on tillage operations alone.
- Therefore efficient weed control is necessary for profitable fruit production.
Significance of weed control in orchard:
- Fruit trees may be much larger than most weeds, but they have root systems that do not compete well with other plants.
- Where, cover crop or weeds grow the bulk of tree roots form in the second and third foot of soil.
- If competition is reduced, the trees form the highest percentage of their roots in the much more biologically active first two feet of soil depth.
- In areas with poor quality soils, the orchardist should not give the best foot of soil to the weeds.
Damages caused by weeds:
- Increase in cost of cultivation: Weed control may take about 30% of total cost of expenditure thereby causing reduction in the net returns.
- Reduction in crop yield: Weeds being hardy and resistant against unfavourable conditions complete for water and nutrition with crop plants and reduces the yield to about 60 – 70%.
- Reduction in the quality of produce: Certain weeds eaten by or fed to the milching animals cause undesirable flavour to the milk. Similarly, if the produces mixed with weed seeds leads to decrease in quality.
- Harbour insect pests and diseases: Weed may act as alternate hosts for many crop pests and diseases.
- Check flow of water in channels: It physically impede the easy flow of irrigation water and cause its wastage by consuming the bulk of irrigation water.
- Some harmful secretions: Some of the weeds (Cyperus rotundus) check the germination and reduce the growth of main crops.
When weeds should be controlled?
- Weed seeds remain viable for long periods. It is known fact that One year seeding is seven years weeding. So weeds should be controlled before they come to flowering.
Methods of weed control are:
- The area under the tree rows cannot be properly mowed, and would become a thick tangle of annual and perennial weeds if left to grow.
- Various methods have been tried over the years to cut down this growth, including mechanical tillage, mulches, and flaming.
- Each one of these alternatively work, but often are very time consuming, expensive, and are carried out, usually, by people intentionally trying to avoid the use of synthetic pesticides.
1. Cultural method : The tillage practice followed in specific garden and occurrence of weeds
2. Fire: Weeds may be burnt using a flame gun.
3. Biological control: Weeds may be killed by releasing suitable parasites.
4. Smothering: If the orchard if fully covering the soil by shade, weeds may be killed by restricting their growth by covering them with suitable mulch of suitable thickness.
5. Chemical weed control: One must be very cautious in using chemicals for weed control or else the crop plants also may be damaged. One should use only selective weedicides. Weedicides may be either organic or inorganic.
Inorganic compounds are: Ammonium sulphate, copper sulphate, ferrous sulphate, borax, sulphuric acid – these are not popularly used in agriculture.
Organic weedicides are:
- DNOC – Dinitro-ortho cresol
- PCP – Pentachlorophenol
- Nitrofen – 2, 4 dichlorophenyl, 4 nitro phenol ether
- Dinoseb – 2 – butyl 4, 6, dinitro phenol
- MCPA – 2 methy 4 chlorophenoxy acetic acid
- 2, 4 D – 2, 4 – dichlorophenoxy acetic acid
- 2,4,5 – T – 2,4,5 trichlorophenoxy, acetic acid
- 2,4 – D.B. – 2,4 dichloro butyric acid
- TCA – Trichloro acetic acid
- Dalapon – 2,2 dichloro propionic acid
- Propanil – 3, 4 – dichloropropionanilide
- Alachlor – 2, chloro, 2, 6 diethyl – N – methoxy – methyl anilide
- Diuron – 3, 4 – dichloro phenyl
- Atrazine – 2 chloro 6 ethyl amino 4 isoprophyl – amine 1,3,5 triazine
They should not be used with most soil residual materials, or products that may injure the young tree if applied to the trunk.
|
Participants