KA3 Crop Protection Flashcards
how do weeds lower crop productivity
compete for light, soil nutrients, water, cast shade (can be overcome by planting in rows), act as hosts for pests and disease
give the differences between perennial and annual weeds
annual weeds have rapid growth, a short life cycle, high seed output and long-term seed viability. perennial weeds live for several years, becoming dormant in winter and growing agin in spring. they have have competitive adaptations such as storage organs and vegetative reproduction
Give examples of pests and diseases that can reduce crop production
Nematode worms, insects, fungi, bacteria, and viruses
State cultural methods of controlling weeds, pests, and diseases
Ploughing, weeding, crop rotation
State the varieties of pesticides and reasons for their use
Herbicides, pesticides and fungicides can be used to control pests when cultural means fail
Describe how systemic herbicides work
Systemic herbicides enter the plant’s transport system and are transported to all parts of the weed, which has a lethal effect. Systemic herbicides kill underground organs and roots preventing regrowth.
Describe how selective herbicides work
Selective herbicides mimic the action of plant growth hormones, causing the metabolism of broad-leafed plants to speed up so they use up their food reserves and die
Describe how systemic pesticides work
They are absorbed by the plant and kill invertebrates when they invest plant material
Describe how fungicides work
Kill fungal parasites which cause disease in crop plants
Describe the effects of toxicity
Some chemicals are harmful to other organisms in the ecosystem
Describe the effects of persistence
Some chemicals fail to break down and remain in the environment
Describe the effects of bioaccumulation
Chemicals can remain in an ecosystem over generations and have harmful effects on an organism
What is biomagnification
An increase in concentration of a chemical moving between trophic levels
What is IPM
Integrated pest management combines cultural, chemical, and biological controls
How does biological control work
Biological control is the control of a pest population by introducing one of its natural enemies - e.g. predators, parasites, pathogens
