Plant Health 2

Question 1

Describe peach potato aphid damage (3)

Answer 1

 sap sucking, identified by yellowing, mottled leaves and curled/puckered/distorted young growth

 excretes honeydew, which leads to the secondary infection of sooty mould. This blocks light, impeding the rate of photosynthesis

 virus transmission between plants, through their stylets e.g. potato leaf roll virus

Question 2

How can beneficial organisms can be encouraged into a garden to help control peach potato aphid (3)

Answer 2

 Blue tits - bird seed and fat balls and hedges and bird boxes for nesting  Parasitic wasps e.g. Ahidus praon can be supplied as parasitised aphids which can be placed on plants in the evening. Rove beetles can also be used  encourage Ladybirds and lacewings by providing overwinter shelter in hollow stems, herbaceous material, crevices in walls etc. or creating ‘insect hotels’

Question 3

pests that cause damage by biting (4)

Answer 3

vine weevil, deer, rabbit, caterpillars

Question 4

pests that cause damage by rasping (2)

Answer 4

slugs and snails

Question 5

define ‘annual weed’

Answer 5

a annual weed completes its life cycle in one growing season i.e. it germinates in spring, grows, flowers, sets seed and dies in one growing season

Question 6

state the characteristics of annual weeds found in recently cultivated soil (3) plus 3 examples

Answer 6

Poa annua, Veronica persica, Chenopodium album - they produce copious amounts of seed - they have shallow fibrous roots - seed can overwinter in the soil and remain viable for many years.

Question 7

problems caused by perennial weeds in an established lawn (5)

Answer 7

 Compete for light as large rosette shaped leaves block out light required by the grasses  Compete for water as large leaves and deep tap roots can absorb water more readily than grasses  Harbour pests and diseases  Cause an uneven playing surface for sports e.g. golf  Appear aesthetically unattractive as the broad leaves and tall flower heads look unsightly

Question 8

how do black bean aphids breathe? (2)

Answer 8

• through tiny openings in the body wall and use of spiracles - blind-ended air filled tubes called tracheae disperse oxygen around the aphids’ body

Question 9

physical controls for Black Bean Aphids (3)

Answer 9

• squashing/rubbing aphids off between finger and thumb - removal of the bean shoot tips by pinching out by hand before the aphids are able to colonise the plant - strong jet of water to wash aphids off without damaging the plant

Question 10

chemical controls for Black Bean Aphids

Answer 10

• fatty acids - pyrethrin - deltamethrin

Question 11

what is meant by plant disease

Answer 11

an abnormal growth and/or dysfunction of a plant caused by an infectious micro-organism (pathogen) e.g. virus, bacteria, fungi.

Question 12

describe damage caused by Honey Fungus (5)

Answer 12

• crown of the tree might die suddenly in hot, dry weather due to failure of the root system. - smaller and paler than average leaves - may fail to flower - or produce a large number of flowers followed by a heavy crop before it dies. - Cracking and bleeding of the bark at the base, and dead or decaying roots

Question 13

describe the method of spread by honey fungus (3)

Answer 13

• spreads via rhizomorphs underground - can spread up to 30m in the top 15cm of the soil - can also spread through direct contact of the roots of infected trees with unaffected ones.

Question 14

describe methods of control Honey Fungus (4)

Answer 14

• Plant species that show some resistance to honey fungus e.g. Ginkgo biloba, Quercus ilex - do not plant susceptible species e.g. Fagus sylvatica, Ligustrum vulgare. - Dig out the whole tree including the stump and as much root as possible and burn - dig trench around tree and bury a butyl rubber sheet to form a barrier to prevent the spread of the rhizomorphs.

Question 15

reasons to control weeds (4)

Answer 15

• To remove competition for light, water and nutrients - To make harvesting crops easier - To remove hosts for pests and diseases - Avoid weeds looking unsightly

Question 16

Chemical control for Aegopodium podagraria in an established shrub border. Name active chemical and mode of action.

Answer 16

Glyphosate translocated

Question 17

Chemical control for Cardamine hirsuta in a newly cultivated soil. Name active chemical and mode of action.

Answer 17

Acetic acid or Fatty acid contact

Question 18

how can pesticide use disturb the natural balance of plant protection in a garden situation. (3)

Answer 18

 Beneficial insects/natural predators that are active can be destroyed particularly in the middle of the day. If beneficials are destroyed biological controls will not be successful

 Overuse of pesticides may cause damage to other plants or destroy natural habitats where beneficial insects/natural predators would overwinter or breed. This could cause the pest population to explode if there are no natural predators

 Excessive use of certain pesticides may cause resistance in pest/disease populations which would result in their increase

Question 19

Describe fasciation

Answer 19

a distorted stem which is flattened in appearance. Flowers can also appear distorted with flattened flower heads from the fasciated stem

Question 20

What happens when you grow an acid-loving plant in an alkaline soil (3)

Answer 20

1. Lime-induced chlorosis occurs where manganese and iron become unavailable to the plant causing interveinal chlorosis/yellowing of the leaves.
2. Photosynthesis is reduced as iron is required to make chlorophyll.
3. The colour of Hydrangea flowers also changes from blue in acid soils to pink in alkaline soils.

Question 21

methods to prevent frost damage (4)

Answer 21

1. Take tender plants into a protected structure e.g. a greenhouse or conservatory
2. Wrap large tender plants, which cannot be relocated in fleece or cover with bracken/straw to protect their growing tips from frost
3. Do not plant tender plants in frost pockets or areas where the early morning sun can damage flowers e.g. Camellias
4. Apply a 75 – 100 mm layer of organic mulch around the base of herbaceous perennials etc. to protect the root zone