3.3 crop protection

Question 1

pesticides

Answer 1

used to kill unwanted pests on crops

Question 2

biological control

Answer 2

uses natural predators to kill pests

Question 3

monoculture

Answer 3

growing one single crop over a wide area

Question 4

why are weeds an issue

Answer 4

causes a significant reduction in productivity of the crop due to competition

they release chemical inhibitors into the soil which further reduces crop growth

act as hosts for crop pests and disease

Question 5

annual weeds (once a year)

Answer 5

grow very quickly
short life cycle
produce lots of seeds
seeds remain dormant but viable for a long period of time

Question 6

perennial weeds (year after year)

Answer 6

already established in the habitat
have storage organs from previous years that provide food in unfavourable conditions
reproduce vegetively

Question 7

examples of plant pests

Answer 7

nematode worm
molluscs
insects
disease

Question 8

how can insects affect plants

Answer 8

act as vectors of disease

Question 9

how s yield decreased by pests

Answer 9

damages leaves which reduces photosynthesis which in turn reduces the energy available to the plant for growth

Question 10

cultural means of crop potection

Answer 10

crop rotation
ploughing
weeding
time of sowing
removal of alternative hosts (weeds)

Question 11

specific pests die out between plantings of same crop

Answer 11

crop rotation

Question 12

perennial weeds damaged or buried

Answer 12

ploughing

Question 13

early hoeing removes annual weeds before they can affect growth of young weeds

Answer 13

weeding

Question 14

systemic herbicides

Answer 14

absorbed into vascular system to kill weed
slower to act than contact but more effective
it reaches underground storage organs and root stopping regrowth

Question 15

stimulates rates of growth in broad leaf plants and exhaust supply until it dies

Answer 15

systemic herbicides

Question 16

destroys all green plant issue in which they come into contact with
short lived
no effects on root so the weed regrows

Answer 16

contact herbicides

Question 17

contact pesticide

Answer 17

kills the insect when it comes into contact with it and leaves the plant with a protective poisonous layer and kills any pests that come into contact with it

Question 18

systemic pesticide

Answer 18

absorbed by the plant and transported to all its parts
sap sucking insects ingest it and die

Question 19

sprayed before fungal attack
can be washed away by rain
newly emerging leaves are unprotected
the fungal spores absorb the poison and die when they land

Answer 19

contact fungicide

Question 20

absorbed by the plant and transported throughout
gives better protection against fungal attack

Answer 20

systemic fungicide

Question 21

how is weather data used as crop protection

Answer 21

can forecast infection and warn farmers so can use fungicides in advance
saves money by only using when necessary

Question 22

problems with chemical pesticides

Answer 22

some pesticides have toxic effects on humans and other animals
persist in the environment
accumulate and magnify in food chains

Question 23

what is bioaccumulation

Answer 23

an increase in the concentration of a chemical in a biological organism over time,

Question 24

disadvantage of biological control

Answer 24

can become an invasive species
prey on or become a pathogen of another species

Question 25

use of more than one method of control

Answer 25

integrated pest management.