Unit 3.5: Crop Protection

Question 1

How do weeds effect crop productivity?

Answer 1

They reduce crop productivity mainly due to competition

Question 2

What are annual weeds?

Answer 2

• They grow from seed and disperse dees in 1 year
• Properties include
  
  • Rapid growth
  • Short life cycle
  • High seed output
  • Long term seed viability
• Examples - chickweed and speedwell

Question 3

What are perennial weeds?

Answer 3

• `lives for more than 2 years, generally dies in winter and brown in spring
• properties
  
  • Storage organs (bulbs, tubers)
  • Vegetative reproduction, only one plant involves, offspring are identical
• examples: dandelion, bramble

Question 4

Types of plant protection chemicals

Answer 4

• systemic chemicals work by: spreading through the vascular system of plants and prevents growth
• selective herbicides work by: having a greater effect on certain plant species, broad leaves plants e.g being absorbed more through wider leaf surface of the weeds than the narrow leaves of cereal
• systemic insecticides, mollucisides and nematocides spread through the vascular system of plants and kill pests feeding on plants

Question 5

What advantage is there in applying fungicides based on disease forecast rather than grafting diseased crop?

Answer 5

You have not lost yield to already damaged crops and you are not using fungicide when not necessary

Question 6

What is biological control?

Answer 6

Biological control involves the introduction of a biological agent which could be a predator, pest, or parasite of the pest

Question 7

What is integrated pest management?

Answer 7

Integrated pest management combined chemical, cultural and biological controls

Question 8

What is the risk when using biological control?

Answer 8

The control organism may become an invasive species, parasite prey or be a pathogen of other species

Question 9

What are problems with using plant protection chemicals?

Answer 9

• There can be bioaccumulation - chemicals can build up to toxic levels over time
• They can be persistent - a high persistence chemical will remain for a long time so if you add more it will build up