Chemical Methods of Crop Protection Flashcards
Selective herbicide
Mimic plant growth hormones. Therefore they increase the growth and metabolism of weeds. This happens to such an extent that the weeds exhaust their food supply and die.
Crop plants absorb little of the chemical.
Are biodegradable and do not cause harm to the soil.
Contact herbicide
They destroy all plants.
Since they are biodegradable, their effect is short-lived.
These herbicides don’t have an effect on underground organs, therefore established weeds with storage organs can re-emerge.
Systemic herbicide
Enter the weeds’ circulatory system.
The chemical is transported to all parts of the weed, which has a lethal effect.
Are slower to act than contact herbicides but are more effective as they can reach and kill underground organs and roots.
Contact pesticide
Can kill when brought into contact with pest in the form of a spray.
They can also form a protective layer of poison residue on plants.
Systemic pesticide
These are absorbed and transported around by the pests, killing them in the process.
Contact fungicide
Sprayed on crops.
When fungal spores land on the crops and germinate they absorb the poison and die.
Rain can wash the fungicide off the plants therefore several applications are needed.
Systemic fungicide
Absorbed by the plant and move all around the plant in the vascular system.
This form of fungicide gives better protection.
