Crop Protection

Question 1

What is a monoculture?

Answer 1

A monoculture is a vast population of a single species of crop plant cultivated over a large area

Often the members of the population are genetically identical providing ideal growing conditions for pests

Question 2

Describe competition

Answer 2

Plants growing side-by-side will compete for light, water, nutrients and space

Question 3

Describe competition in a monoculture

Answer 3

Competition among members of the monoculture is reduced by spacing the plants out however weeds can grow in these gaps and cause competition

Question 4

What is the effect of weeds as competition?

Answer 4

Weeds reduce productivity because they cause competition and release chemical inhibitors which reduce crop growth

Question 5

Characteristics of perennial weeds

Answer 5

Asexual reproduction

Storage organs provide food without the need for photosynthesis

Question 6

Characteristics of annual weeds

Answer 6

Rapidly produce flowers due to the short life span

Produces a large number of seeds

Produces which can lie dormant for very long periods of time

Grow very quickly

Question 7

Harmful effects of invertebrate pests

Answer 7

Damage to leave reduces photosynthesis, hence less sugar produced

Lots of sugary sap reduces energy supply to tissues

Question 8

Describe plant diseases

Answer 8

Plant diseases are caused by pathogens such as fungi, bacteria or viruses which are often carried by invertebrates

Diseases cause poorer yield, Reduced market ability (blemished), reduced storage life (degrade too quickly)

Question 9

Methods of crop protection/ control of pests through cultural means

Answer 9

Crop rotation

Ploughing

Removal of alternative hosts

Question 10

Describe crop rotation as a cultural method of controlling pests

Answer 10

Crop rotation helps put nitrogen back in the soil

It is the practice by which each of a series of very different types of crop plant is grown in turn on the same piece of ground

Pests will be unlikely to survive in the time it takes for its host plant to return to the same plot of land

Crop rotation works best against soil inhibiting pests that are only able to attack a narrow range of host plants

Question 11

Describe ploughing as a cultural method of controlling pests

Answer 11

Ploughing is we are the top 20 cm of soil is turned over and many of the perennial weeds are buried to a depth at which they die and decompose

The crop seeds can be planted and become established before the weeds return

Question 12

Describe removal of alternative hosts as a cultural method of controlling pests

Answer 12

In the absence of their favourite host plant many insect pests are able to survive and breed on alternative hosts such as weeds bordering the field so removing these helps to control pests

Question 13

Methods of crop protection/ control of pests through chemical means

Answer 13

Herbicides which kill weeds

Pesticides which kill invertebrates

Fungicides which kill fungal parasites

Question 14

Types of herbicides

Answer 14

Selective

Systemic

Contact

Question 15

Types of pesticides

Answer 15

Contact

Systemic

Question 16

Types of fungicides

Answer 16

Contact

Systemic

Question 17

Describe Selective herbicides

Answer 17

Mimic the action of plant growth hormones

Speeds up metabolism of broad leaved plants which uses up food and kills them

Narrow leaved plants aren’t affected by selective herbicides

Usually biodegradable

Question 18

What should a plant protection chemical be ideally?

Answer 18

Specific to the pest concerned

Short left (shouldn’t persist in the environment and should be broken down into harmless byproducts)

Safe for animals and humans

Question 19

What are the problems with using chemicals for crop protection and pest control?

Answer 19

Toxicity - plant protection chemicals can be poisonous to more than just the pest

Persistence – Some are not biodegradable so remain in the environment for long periods of time

Bioaccumulation - when concentrations of chemicals increase as you go up trophic levels

Producing a resistant population

Question 20

What is biological control?

Answer 20

Biological control is the reduction of a pest population by the deliberate introduction of one of its natural enemies

However it may not kill all the best (but it would cause economic damage)

Question 21

What is integrated pest management?

Answer 21

A combination of techniques including chemical control, biological control and cultural means

It sets out to reduce the need for pesticides while bringing pest populations down to a level at which they can no longer cause economic damage

Question 22

What are fungicides?

Answer 22

Fungicides can be used to protect crops when environmental conditions and disease forecasts suggest that infection is likely

Prevention is more effective than treatment

Question 23

What are contact chemicals for control of pests?

Answer 23

Kills pests which are in direct contact with chemical

Question 24

What are selective chemicals for control of pests?

Answer 24

Designed to only affect one type of pest and leave other organisms unharmed

Question 25

Describe systemic herbicides

Answer 25

Kills all plant matter and can clear an area before planting crops

Effective as they reach storage organs and root systems

Question 26

Describe systemic fungicides

Answer 26

Sprayed onto crops and absorbed by plant tissues giving them protection from disease causing fungus

Not washed away by rain giving better protection

Only kill fungi

Question 27

Describe systemic pesticides

Answer 27

Sprayed onto crop plants and absorbed by plant tissues and will kill pests when they feed on the plant tissues

Question 28

Describe contact herbicides

Answer 28

Kill all green plant tissue that they come into contact with

Biodegradable- their effect is short lived

Roots survive so plants with storage organs can regrow

Question 29

Describe contact pesticides

Answer 29

Work in two ways:

• kills invertebrates coming into contact with spray
• leaves a protective layer on plant which will kill future invertebrates

Question 30

Describe contact fungicides

Answer 30

Sprayed onto crops and absorbed by fungal spores when germination starts casting the fungi to die

Easily washed away by rain so needs to be reapplied regularly