Plant diseases + defences

Question 1

what type of pathogens can plant diseases be caused by

Answer 1

• bacteria
• viruses
• fungi

Question 2

what organisms can plants diseases be caused by

Answer 2

• worms
• insects e.g. aphids

Question 3

what are 7 signs of plant diseases

Answer 3

• stunted growth
• spots on leaves
• area of decay (rot)
• abnormal growth e.g. galls, lumps
• malformed stems + leaves (curling)
• discolouration of leaves (yellow , black spots)
• presence of pests

Question 4

identification of plant diseases can be made by :

Answer 4

• reference to a gardening manual or website
• taking infected plants to a laboratory to identify the pathogen
• using testing hits that contain monoclonal antibodies

Question 5

what is a fungal disease in plants

Answer 5

Rose Black Spot

Question 6

what is a viral disease in plants

Answer 6

Tobacco Mosaic (TMV)

Question 7

what are the symptoms of rose black spot

Answer 7

• purple/ black spots on leaves
• yellow leaves + drop off
• Stunted growth –> rate of photosynthesis decreases

Question 8

how is rose black spot transmitted

Answer 8

• fungus thrives in wet + windy conditions
• through air or water
• direct contact by gardeners

Question 9

prevention of Rose black spot

Answer 9

• removing + destroying infected leaves –> otherwise fungus will spread

Question 10

treatment of rose black spot

Answer 10

fungicides

Question 11

symptoms of TMV

Answer 11

• small patches of light green, brown, yellow appear on leaves –> infects chloroplasts
• leaves smaller than usual:
  
  • affects rate of photosynthesis –> stunted growth

Question 12

how is TMV transmitted

Answer 12

contact between plants:
- naturally
- human contact

Question 13

prevention of TMV

Answer 13

• remove all decaying leaves
• burn suspected infected leaves –> prevent further contamination

Question 14

cure for TMV

Answer 14

no cure

Question 15

when does stunted growth occur in regard to ion deficiencies

Answer 15

lack of nitrates

Question 16

what happens when there is a lack of magnesium ions

Answer 16

chlorosis

Question 17

what happens when there is a lack of nitrates and why

Answer 17

stunted growth –> nitrates needed to produce amino acids –> needed for protein synthesis –> which is essential for growth

Question 18

what occurs when there is a magnesium ion deficiency and why

Answer 18

Chlorosis –> Mg ions needed to make chlorophyll –> not enough chlorophyll = chlorosis + less photosynthesis

Question 19

explain why leaves turn yellow when chlorosis happens

Answer 19

chlorophyll reduced = green pigment –> yellow colour