2. Tools for prevention
Avoid the entry of weed seeds onto the farm through
• Manures
• Mulching material
• Intercultivation equipments
• Animals
• Water etc.
3. Different practices to control
• Cultural
• Mechanical
• Biological
• Chemical (organically approved)
Liebman and Gallandt, 1997
4. Cultural Practices
Improve crop competitiveness
• Increase crop density through narrow row
spacing and increased seeding rate .
• Use transplants, rather than seed.
• Choose competitive crop cultivars.
• Manage fertility according to crop needs; avoid
excess application.
• Spot application of fertilizers.
5. Intercropping
• Having different plant types growing together enhances weed
control by increasing shade and increasing crop competition
with weeds through closer crop spacing.
Ex:
• soybean +wheat
• Sugarcane + finger millet
• Sunflower + groundnut
7. Crop Rotations
• Weeds tend to infest crops with similar life cycles
• Crop rotations limit the buildup of weed populations and
prevent major weed species.
• Altering, narrowly spaced crops with closely spaced crops,
shallow rooted with deep rooted crops, cold with warm season
crops.
8. Allelopathy
• Allelopathy crops are especially useful because they have the ability
to suppress other plants that attempt to grow around them.
• Rye is one of the most useful allelopathic cover crops which kills
weeds like ragweed (by 43%), pigweed (95%), and common
purslane (100%).
• North Carolina researchers investigated combinations of herbicide
use and cover crop plantings on weed control and reported Rye and
clover showed the highest weed control without herbicides.
10. Smother Crops
• Prevent seeds from germinating by blocking light, can smother
out some weeds.
• In northern states, oats are commonly planted as a “nurse
crop” for alfalfa, clover. The oats grow between in the place of
weeds and avoid weed emergence.
While in Peshawar smother crops are
Sorghum-sudan and lablab bean
• Ex: Mustard as cover crop in Ragi.
14. Irrigation
• Drip irrigation is more water efficient .
• Also by directing water to the crop it minimizes weed
germination and reduces need to cultivate.
15. Mulching
• Covering the surface of soil to avoid the entry of sunlight by
using locally available materials like straw, plastic, papers,
wood pieces, dry leaves etc.
• Prevent seeds from germinating by blocking light, can smother
out some weeds.
18. Mechanical
methods
• Cultivation of the soil with a variety of different tools can
control emerged weeds and disrupt weed reproduction cycles.
• Cost effective
• Time consuming
22. Flame weeding
• Burning of weeds by flame.
• Intense heat causing the cell sap to expand and disrupt cell
walls.
• Pre-emergent, and post-emergent flame weeding has been
successful in a number of crops.
• Flaming has generally proved most successful on young
broadleaf weeds.
• It is reportedly less successful on grasses.