R2103 Maintaining Plant Health

Question 1

(1.1) Explain what is meant by PHYSICAL (mechanical) control of pests and disease.

Give one example of PHYSICAL control.

Answer 1

Physical control refers to the mechanical or hand controls where the pest is actually attacked and destroyed and is particularly effective as a control method for weeds.

Cultivation, burning, removal by hand or by the use of a hoe are all used to destroy weeds and prevent reproduction.

Question 2

(1.1) State TWO benefits and TWO limitations of PHYSICAL control.

Describe how risk to people and the environment are minimised.

Answer 2

Benefits:
Unlikely to cause harm to the environment.
Can be very targeted and effective for small infestations.

Limitations:
Not effective for large areas of infestations.
Relies on regular monitoring and physical intervention.

Physical controls pose less risk to people or the environment but in some areas personal safety may be compromised - Know what weeds you’re handling, some plants can cause skin irritation and hoes have sharp edges and may pose a risk if not handled appropriately.

Question 3

(1.1) Explain what is meant by CULTURAL control of pests and disease.

Give one example of CULTURAL control.

Answer 3

Cultural control is understanding and manipulating the environment where the plant is growing to help reduce threats to plant health. Essentially a preventative course of actions against weeds and pests.

Companion planting is said to reduce certain pests and diseases, the practice of growing different plants near others. While certain crops do not kill pests they can discourage and deter. There are many combinations such as French marigolds deterring glasshouse whitefly and mint planted around cabbages to discourage the cabbage white butterfly.

Question 4

(1.1) State TWO benefits and TWO limitations of CULTURAL control.

Describe how risk to people and the environment are minimised.

Answer 4

Benefits:
Environmentally acceptable.
Can be very specific.

Limitations:
May be labour intensive.
May be ineffective where large infestations occur or where a large area of crops is found.

Very few risks to people and the environment but garden hygiene is important in reducing outbreaks of pests and diseases, outbreak effects can be reduced by practicing good husbandry techniques such as disposing of weeds correctly.

Question 5

(1.1) Explain what is meant by CHEMICAL control of pests and disease.

Give one example of CHEMICAL control.

Answer 5

The use of chemicals for protecting plants against pests and diseases and controlling weeds, a widespread method and effective.

The use of insecticides to control pests by either killing on contact or by using systemic pesticides that enter the phloem of the plant and subsequently ingested by the sap sucking pests.

Question 6

(1.1) State TWO benefits and TWO limitations of CHEMICAL control.

Describe how risk to people and the environment are minimised.

Answer 6

Benefits:
Fast acting and many can target a specific problem.
Particularly effective when large outbreaks occur.

Limitations:
Broad spectrum pesticides are indiscriminate and can kill beneficial insects as well as harmful pests.
Chemicals may pose a health risk to people and the environment.

Risks include leaving poisonous residues on the crops, leaving pollutants in the neighbourhood, contaminating other crops and polluting waterways. Risks to people and the environment can be minimised by following safety precautions and usage instructions to the letter, ensuring the product is stored carefully and disposed of safely.

Question 7

(1.1) Explain what is meant by BIOLOGICAL control of pests and disease.

Give one example of BIOLOGICAL control.

Answer 7

Involves the use of a living organism to predate or attack a pest, commonly used in controlled environments such as glasshouses.

The ladybird beetle larva prey and feed on aphids.

Question 8

(1.1) State TWO benefits and TWO limitations of BIOLOGICAL control.

Describe how risk to people and the environment are minimised.

Answer 8

Benefits:
Specific predators can be introduced to control specific pests.
Environmentally acceptable.

Limitations:
Critical to match predator levels against level of pest infestation.
In glasshouses, flying predators may escape rather than remain where required.

There is little hazard or risk to either person or environment. There is a small possibility that releasing a predator into the environment may result in species other than the pest being attacked as well.

Question 9

(1.2) Explain the importance of natural balances in plant protection to include beneficial organisms.

Answer 9

Many pests have predators that help keep pest populations under control. When pesticides are used to kill the pest they can be very effective in killing off the predator- resulting in the pest re-establishing the population after the effects of the pesticide have gone while the predator may be slower in re-establishing a large enough population to control the infestation.

Beneficial insects, animals and reptiles may be encouraged to remain within the garden so long as they have a suitable habitat, protection from predators themselves and a steady supply of food.

Gardening practices may destroy habitats that desirable insects (or the immature forms of) may require to thrive in the garden, eg removing Urtica dioica which is food plant of the larvae of a number of British butterflies like Inachis io.

Question 10

(1.2) Give TWO examples of how beneficial organisms can be encouraged.

Answer 10

Birds - These eat caterpillars, encourage by providing nest boxes, small source of fresh water and supplementing their natural diet in colder seasons.

Compost heaps provide organic matter for soil as well as a habitat for slow worms and hedgehogs.

Question 11

(1.2) Give TWO examples of how garden practices can disturb these balances, including the use of pesticides.

Answer 11

Excessive use of pesticides or use of broad-spectrum pesticides can harm predator insect populations to levels where control of pest infestations is reduced and a food source to higher organisms such as birds is also reduced.

Removal of plants used as a food source to beneficial organisms such as Urtica dioicia for numerous butterfly species or over-cultivating/wrong timing of cultivation disturbs or destroys habitat for soil organisms like earthworms that assist in the breakdown of organic matter which improves soil.

Question 12

(1.2) Describe TWO methods that can be used to restore and maintain the natural balances to minimise the need for pesticides.

Answer 12

Many plants can withstand an attack of some pests provided their other environmental needs are met to reduce plant stress such as adequate light, appropriate water supplies and optimal soil conditions.

Introduce or encourage predators to manage pests by providing a suitable habitat for populations to thrive.

Question 13

(1.3) Describe how the selection of plants can help to avoid plant health problems including:

Choice of resistant cultivars.
Growing plants appropriate to a situation and soil.

Answer 13

Select cultivars resistant to pests and diseases wherever possble - this will prevent the build up of zones of infection and infestation.

Avoid locating plants where they are like to encounter stressful growing conditions like planting tender plants in exposed situations. Plants should also be selected to suit the soil conditions, an ericaceous plant will not tolerate alkaline pH soils for long due to nutrient deficiencies, when plants are stressed they are more prone to attack from diseases and pests.

Question 14

(1.3) Describe ONE example of an appropriate use of a resitant cultivar.

Answer 14

To provide better displays and lengthen the life of Roses by using cultivars resistant to powdery mildew, black spot and rust.

Question 15

(1.3) Describe TWO examples of an appropriate choice of a plant for a NAMED situation.

Answer 15

Hippophae rhamnoides - Coastal Areas

Rhododendron ‘Ginny Gee’ - Rock Garden

Question 16

(2.1) Describe what is meant by a weed, to include ‘a

plant growing out of place’.

Answer 16

A weed may be described as a plant growing where it is not wanted, where it may compete for space, water, light, nutrients or carry pests and diseases.

Question 17

(2.1) Describe how weeds cause problems to include:

The reduction of plant growth, competition for light, nutrients and water.

Answer 17

Weeds compete for light, often growing rapidly and shading out others. They also remove available nutrients from the soil causing a potential deficiency in the desired plants. Poor weed control results in slower growth and declining health of the desired plant as weeds left unchecked will at least lead to water stress.

Question 18

(2.1) Describe how weeds cause problems to include:

The reduction of the visual appeal of plantings.

Answer 18

Visual impact of weeds appearing in a well designed and kept garden can ruin the whole aesthetic from the order, colour and style. A few years of neglect can cause entire gardens to become overwhelmed by weeds.

Question 19

(2.1) Describe how weeds cause problems to include:

The role of weeds as alternate hosts for
plant pathogens, to include white blister
rust of brassicaceae and clubroot.

Answer 19

Weeds often harbour pests and diseases. These can quickly spread among desired plants when weeds susceptible of pests and diseases are present.

Capsella bursa-pastoris (shephers’s purse) is susceptible of both Clubroot and white blister rust which commonly infects Brassicaceae.

Question 20

(2.2) State what is meant by EACH of the following
types of weed and give the botanical names of TWO examples:

EPHEMERAL

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 20

EPHEMERAL

Generally defined as plants that complete two or more life cycles in a year. This habit gives such plants huge propensity for reproduction and a competative edge as a weed as many produce thousands of seeds in a single cycle.

Cardamine hirsuta (hairy bitter cress)
Capsella bursa-pastoris (Shepherds purse)

Question 21

(2.2) State what is meant by EACH of the following
types of weed and give the botanical names of TWO examples:

ANNUAL

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 21

ANNUAL

Defined as weeds that complete one life cycle in one year.

Dormant seeds in winter.
Seed germinates when temperature warms (spring onwards)
Flowers are produced when plant is big enough for location.
Plant enters senescent phase when seeds are produced.
Seeds are dispersed in later summer early autumn and lie dormant over winter.

Veronica persica (Speedwell) 
Poa annua (Meadow grass)

Question 22

(2.2) State what is meant by EACH of the following
types of weed and give the botanical names of TWO examples:

PERENNIAL

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 22

PERENNIAL

Defined as a weed that will survive from year to year often dying back in the winter (if herbaceous) and often having underground storage organs or roots.

Ranunculus repens (creeping buttercup) 
Aegopodium podagraria (ground elder)

Question 23

(2.2) Descibe how these types of weeds (Ephemeral, Annual, Perennial) relate to horticultural situations to include:
State the botanical names of TWO weeds associated with EACH of these situations.

RECENTLY CULTIVATED SOIL
Herbaceous perennial borders
Woody Perennial plantings
Lawns

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 23

RECENTLY CULTIVATED SOIL

Most garden soils contain dormant weed seeds waiting for the right conditions to germinate, cultivating the soil may give these seeds the correct conditions such as light and warmth to sprout into seedlings.

Poa annua (annual meadow grass)
Senecio Vulgaris (groundsel)

Question 24

(2.2) Descibe how these types of weeds (Ephemeral, Annual, Perennial) relate to horticultural situations to include:
State the botanical names of TWO weeds associated with EACH of these situations.

Recently cultivated soil
HERBACEOUS PERENNIAL BORDERS
Woody Perennial plantings
Lawns

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 24

HERBACEOUS PERENNIAL BORDERS

Weeds that grow in the midst of a herbaceous perennial border require preventative measures to avoid having to dig the whole border to remove weed roots.

Elymus repens (couch grass)
Petasites fragrans (winter heliptrope)

Question 25

(2.2) Descibe how these types of weeds (Ephemeral, Annual, Perennial) relate to horticultural situations to include:
State the botanical names of TWO weeds associated with EACH of these situations.

Recently cultivated soil
Herbaceous perennial borders
WOODY PERENNIAL PLANTINGS
Lawns

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 25

WOODY PERENNIAL PLANTINGS

The presence of ‘open’ soil allows for invasion of weeds such as woody perennials which often require dificult and costly but necessary mechanical removal.

Hedera helix (common ivy)
Rubus fruticosus (brambles)

Question 26

(2.2) Descibe how these types of weeds (Ephemeral, Annual, Perennial) relate to horticultural situations to include:
State the botanical names of TWO weeds associated with EACH of these situations.

Recently cultivated soil
Herbaceous perennial borders
Woody Perennial plantings
LAWNS

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 26

LAWNS

Patches of bare earth in newly sown or establish lawns can be invaded by wind-blown seeds or dormant seeds already present in the soil, with little competition from the turf the weeds can establish quickly. Periodic re-infestation occurs in mature turf from ‘imported’ weed seeds or creeping perennials.

Ranunculus repens (creeping buttercup)
Trifolium pratense (red clover)

Question 27

(2.3) State what is meant by CONTACT, translocated and selective herbicides.

Describe ONE situation where EACH type of herbicide can be used appropriately.

State the active ingredient in ONE exmaple in EACH type of herbicide.

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 27

CONTACT
The chemical kills only what it touches, very effective for annual weed control but not perennials.

USE: A path with a crop of seedling weeds

Acetic acid is the basis for some contact herbicides eg: Garden Weedkiller - Vitax

Question 28

(2.3) State what is meant by contact, TRANSLOCATED and selective herbicides.

Describe ONE situation where EACH type of herbicide can be used appropriately.

State the active ingredient in ONE exmaple in EACH type of herbicide.

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 28

TRANSLOCATED
The Chemical is absorbed by the plant through the roots or leaves and moved to all parts where it interrupts weed growth. Very effective for perennial weeds.

USE: Broad-leaved or serious perennial weed infestations eg nettles/brambles though may require a series of treatments.

Glyphosphate found in Path and Patio Weedkiller - Bayer

Question 29

(2.3) State what is meant by contact, translocated and SELECTIVE herbicides.

Describe ONE situation where EACH type of herbicide can be used appropriately.

State the active ingredient in ONE exmaple in EACH type of herbicide.

(NOTE: I have split this question up due to the amount of information contained in the answer. The term(s) highlighted in CAPITALS are the focus of the answers required for this individual flash card)

Answer 29

SELECTIVE
In appropriate dilutions some herbicides offer selective capability, discouraging/controlling the weed while other plants remain unaffected and continue to develop. Broader leaved weeds absorb the herbicide where the narrow-leaved grasses absorb less herbicide and are hardly affected.

USE: To eliminate weeds from lawns withough damanging or killing turf.

2,4-D found in Resolva Lawn weedkiller.

Question 30

(3.1) State what is meant by the term ‘plant pest’.

Answer 30

By definition is an animal which feeds on plants either causing direct physical damage or introducing disease into the plant through its activity.

Question 31

(3. 1) Describe the damage done by:
(3. 2) NOT REQUIRED
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

RABBITS

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 31

RABBITS
DAMAGE:
-Eats wide range including young and established plants.
-Some plants not susceptible when mature may be vulnerable when growth is soft and young.
-Tree bark is gnawed, if ring barked by feeding the tree will eventually die.

FEEDING METHOD: Biting, sign of rabbit damage is herbaceous plants being grazed down to the ground.

CONTROL: Chemical – Rabbit repellents applied to vulnerable plants though requires reapplication after wet weather.
Physical – Spiral tree guards around individual young trees.

Question 32

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

CABBAGE WHITE (LARGE WHITE) BUTTERLY LARVAE

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 32

CABBAGE WHITE (LARGE WHITE) BUTTERFLY LARVAE
DAMAGE: Larvae feed in colonies when hatching from eggs laid in cabbages

FEEDING METHOD: Biting, eats leaves.

LIFECYCLE:
Involves a complete metamorphosis
1: Egg
2: Larva (the stage where damage is caused to plants)
3: Pupa (Chrysalis)
4: Adult

CONTROL: Chemical – Insecticides sprayed on brassica crops to kill the larvae as soon as they are hatched.
Physical- Use of fleece over the crop will prevent egg-laying by adult butterflies.

Question 33

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

BLACK BEAN APHID

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 33

BLACK BEAN APHIDS
DAMAGE: Causes extensive damage, leaf curling, damaged stem tips and weakened crop. Sooty moulds caused by and grow on the honeydew which is exuded by the aphids. Transmits viruses from plant to plant.

FEEDING METHOD: Sucks sap of host plants through a stylet.

LIFE CYCLE: 2 separate types of host plant depending on the season. Reproduce asexually (Give birth to live young) and sexually (Eggs) Winged and wingless versions. Whole life cycle can take just weeks and there are many generation in one growing season.

1: Black Bean aphid survives the Winter as an egg on Euonymus. The aphids which emerge in late Winter/early Spring are all female and feed on the young growth of the host shrubs.
2: When the host shrub’s leaves become tough, winged females are produced which fly to the Summer host, particularly broad bean. This house move usually happens in May.
3: Once on the Broad bean, the population explodes as they give birth to live young which does not involve fertilisation. (Asexual reproduction)
4: After feeding on herbaceous plants over the Summer, winged male and female aphids are produced in Autumn which migrate to the shrubby host plants, mate and lay eggs. (Sexual reproduction) Here they will over Winter as eggs.

CONTROL: Physical - A fleece would prevent the invasion.
Chemical – Systemic insecticides effective provided the treatment is thorough.

Question 34

(3. 1) Describe the damage done by:
(3. 2) NOT REQUIRED
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

PEACH POTATO APHID

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 34

PEACH POTATO APHID
DAMAGE: Causes extensive damage- leaf fall, flower dropping and general stunted growth. Sooty moulds caused by and that grow on the honeydew which is exuded by the aphids. Transmits viruses from plant to plant.

FEEDING METHOD: Sucks sap of host plants through a stylet.

CONTROL: Physical – removal of over-wintering host plants such as Prunus to reduce or stop infestation in the following season.
Biological – Releasing natural predators (lacewing larvae/ladybirds) onto affected plants.

Question 35

(3. 1) Describe the damage done by:
(3. 2) NOT REQUIRED
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

TWO SPOTED SPIDER MITE

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 35

TWO SPOTTED SPIDER MITE
DAMAGE: Severe pest- plants may be stunted and killed. First signs are yellowish speckled leaves from loss of chlorophyll, in severe cases foliage turns bronze, shrivels and dies.

FEEDING METHOD: Sucks cell contents from leaves causing the damage, usually worse when combined with water stress.

CONTROL: Cultural – keep glasshouse humidity high and spray plants with a fine mist of water.
Physical – destroy infested plants and pick up any fallen leaves.

Question 36

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

GLASS HOUSE WHITEFLY

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 36

GLASSHOUSE WHITEFLY
DAMAGE: Mottling and yellowing foliage, wilting presence of sooty moulds from honeydew exuded from whitefly.

FEEDING METHOD: Piercing mouthparts withdraw large quantities of sap.

LIFE CYCLE:

1: Egg
2: First instar (immature)
3: Second instar (immature)
4: Third instar (immature)
5: Fourth instar (immature)
6: Adult

CONTROL: Biological – Introducing a parasitic wasp, more effective when populations are still low.
Physical – maintain and monitor yellow sticky traps to detect invasions early.

Question 37

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

VINE WEEVIL

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 37

VINE WEEVIL
DAMAGE: Adults cause characteristic notching around leaf margin by biting and chewing, larvae live in soil and feeds on roots of the plant and causes most destructive damage.

FEEDING METHOD: Biting of leaves as adults and roots as larvae.

LIFE CYCLE:

1: Egg
2: Larva
3: Pupa
4: Adult

CONTROL: Biological – Parasitic nematodes like Steinernema spp. can control weevil larvae especially in container grown plants.
Chemical – foliar sprays of insecticides placing a stomach poison on the leaves of plants which are consumes by adult weevils, critical to apply after adults emerge prior to egg laying stage in lifecycle but as adults are active or long periods several sprays may be needed.

Question 38

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

SLUGS

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 38

SLUGS
DAMAGE: Eats soft tissues of leaves, stems and roots.

FEEDING METHOD: Rasping

LIFE CYCLE:

1: Egg
2: Juvenile
3: Adult

CONTROL: Physical – Collecting slugs by hand after dark or in damp conditions regularly. Squash slugs or drop into bucket of salty water.
Biological – encourage natural predators such as toads, slow worms and hedgehogs by providing a natural habitat where possible.

Question 39

(3. 1) Describe the damage done by:
(3. 2) Decribe in outline the life cycle of:
(3. 3) Describe the feeding method of:
(3. 4) Describe TWO different methods of minimising (including preventing) the effects of the plant pest; methods should be selected from more than one of the control options available (chemical, physical, cultural, biological)

POTATO CYST EELWORM

(NOTE: Due to the lenth of the list of the pests and required information for each answer I have combined the questions and answers for each one under each pest name)

Answer 39

POTATO CYST EELWORM
DAMAGE: Only affects Solanum tuberosum (potatoes), Solanum lycopersicum (tomatoes) and Solanum dulcamara (woody nightshade). Initially, crops display patches of poor growth and affected plants may show chlorosis and wilting, with poor top growth. These symptoms develop from the ground upwards.

FEEDING METHOD: Sap sucking with stylet.

LIFE CYCLE:

1: Cysts filled with hundreds of eggs are exposed to hatching factors, chemicals exuding from developing potato roots.
2: Juveniles develop within each egg, the first moult happens inside the egg while the stylet forms. The stylet is the organ which will help to cut through the egg shell and will later be used to puncture plant cells for feeding.
3: Second stage juveniles hatch from the eggs. They are microscopic worm-like creatures which enter the roots and feed internally on plant cell contents.
4: When almost mature, the female nematodes become globular in shape and burst through the root wall and are then fertilised by males.
5: When the potatoes are harvested and pulled out of the soil the cyst are simultaneously pulled off and stays in the soil.
6: The cysts will harden, dry and change colour. The cysts allow the succeeding generation to survive for an extended period of time in the soil until a suitable host plant is growing nearby. There is one generation a year on outdoor crops but two generations may be possible on glasshouse tomatoes.

CONTROL: Cultural – Long rotation. Where eelworm have been present don’t plant potato or tomato plants until a period of at least 7 years since the last planting. Ensure all potatoes are collected after harvesting, any escapees must be removed as soon as they sprout in spring.
Physical – Burning any infected plant material.

Question 40

(3.3) Describe the method of breathing used by insect pests.

Answer 40

Understanding biology of insects deepens knowledge on how to control pests

Breathing (gas exchange) is done by simple diffusion through cells walls.

1: Air enters spiracles (respiratory openings) and moves through tracheal system, each tracheal tube ends in a moist tracheole- a special cell for exchanging gasses with another cell in the body.
2: In the tracheole, oxygen dissolves into the tracheole liquid.
3: Via simple diffusion, oxygen then moves into the living cell and carbon dioxide enters the tracheal tube.
4: Carbon dioxide, a metabolic waste product, leaves the body through the spiracles.

Question 41

(3.4) Describe how the knowledge of the life cycle and the biology of pests named in 3.2 (Cabbage white (large white) butterfly, Black bean aphid, Glass house whitefly, Vine weevil, Slugs, Potato cyst eelworm) contribute to the success of their control.

Answer 41

Life cycle is important because the species can be more vulnerable at different stages, may not cause damage at some stages and may not be present at particular stages at all (eg migration for summer onto different host plants as in Black Bean Aphids).

It is important to recognise symptoms of damge to ascertain which stage of the life cycle the pest may be in in order to apply correct methods of control.

Ecdysis is the moulting of the skin in invertebrates. The process of moulting is done during growth periods and a new larger covering is formed. Some pesticides interrupt the process of ecdysis preventing a new cuticle being developed.

Ovicides can be used during overwintering stages of eggs and larvae eg: tar-oil.

Adult flying stages can be controlled through exclusion eg: netting to exclude the large cabbage white butterfly.

Larvae of winter moth can be trapped using grease bands.

Different stages of life cycles cause different damage and require varying methods of control.

Question 42

(4.1) State what is meant by the term ‘plant disease’.

Answer 42

A fungal, bacterial or viral organism which interferes with the normal growth rate of plants, producing visible symptoms which reduce the economic or aesthetic quality.

(When these organisms infect plants they are considered to be pathogens (disease producing organisms). In general most diseases that affect plants are fungal.)

(Infectious diseases differ from non-infectious (abiotic disorders) because they are caused by specific plant pathogens. Biotic causes are living organisms (pathogens) while abiotic causes usually involve the environment as in physical disorders.)

Question 43

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

GREY MOULD

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 43

GREY MOULD (Botrytis cinerea)

DAMAGE: Most common species to attack flowering plants such as Dahlia, Gladiolus and Begonia. On Fragaria it can cause heavy fruit losses. Causes a soft decay of plant tissues accompanied by a growth of fuzzy grey-brown mould.

SPREAD: When spring weather conditions are favourable they produce spores. These are dispersed by wind, air movement, water splash and pesticide sprays. Once a plant is infected, botrytis may spread to all parts depending on its species and variety.

CONTROL: Physical – On a small scale, infected material should be picked off and burned.
Cultural – Ensuring plants are spaced well apart to avoid spread and manage humidity in enclosed spaces by providing adequate ventilation and airflow.

Question 44

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

STRAWBERRY POWDERY MILDEW

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 44

STRAWBERRY POWDERY MILDEW (Podosphaera aphanis)

DAMAGE: Foliar infections cause small white patches of fungus to grow on the lower leaf surface, mycelium grow and produce a powdery appearance. Margins of heavily affected leaves can curl upwards, flowers might be aborted or go on to produce misshapen fruits.

SPREAD: The disease is a parasite that only affects living tissues of the strawberry. Infects living green leaves in the nursery. Infected transplants are the initial source of infection. Grows and infects optimally at moderate to high temperatures between 15.5 – 26.5 degrees Celsius. Moistures such as rain, dew and overhead irrigation will halt the fungus.

CONTROL: Cultural – drier and higher temperatures more prevalent and infections more severe in protected culture, top-down irrigation practices with foliar spraying to introduce more moisture.
Physical – use mildew-free transplants and disease resistant cultivars.

Question 45

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

DAMPING OFF

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 45

DAMPING OFF (Pythium)

DAMAGE: The single term used to describe underground, soil line or crown rots of seedlings due to unknown causes. Term covers several soil-borne diseases of plants and seed-borne fungi. Seedlings may fail to emerge (pre-emergence damping off), seedlings collapse often at soil level and often submerged in a mass of whitish fungal growth- known as post emergence damping off. Seeds can rot before germination, shoots form freshly germinated seeds can rot before they emerge from growing media, or young seedlings rot at the base after they have emerged and collapse.

LIFE CYCLE:

1: Pythium survives as oospores in plant debris, resting spores which are resistant to unfavourable conditions, especially dehydration.
2: Germination of the oospores is stimulated by exudates from roots of a susceptible host nearby. The oospores germinate and form so-called sporangia from which subsequently zoospores are produced. Zoospores are spores with flagella (A long, whiplike appendage that functions as a cellular organ of locomotion), which enable the spores to move through water.
3: The zoospores are chemically drawn to the growing roots of young plants and move towards them through the soil water. They infect the roots through small wounds, where the side roots are formed or through other similarly damaged spots.

SPREAD: On the infected plant, new sporangia with zoospores are formed, that allow the disease to spread to neighbouring plants. Oospores are dispersed when soil particles are moved around by humans or machinery. Pythium can survive very well in the soil or substrate in the absence of plants.

CONTROL: Cultural – sow seeds thinly to avoid over crowding of plants and provide constant air movement, ideally air should move freely 24 hours a day but not directly aimed at the plants.
Chemical – No suitable products available to the amateur, Filex is available professionally; used as a drench to sown trays or seedlings. Suitable fungicides may be applied as a soil drench after sowing or incorporated into the soil before sowing as a dust.

Question 46

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

HONEY FUNGUS

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 46

HONEY FUNGUS (Armillaria mellea)

DAMAGE: Fungus that attacks wide range of shrubs and trees. Found as white mycelia and bootlaces beneath the bark. Also presents as toadstool clusters as base of plant. Causes yellowing of leaves, early leaf fall, premature autumn colour, splitting of the bark, exudation of resin, dieback and eventual death of the whole plant.

LIFE CYCLE:

1: Armillaria spores present around dead plants and stumps.
2: Rhizomorphs grow on and around roots and infects healthy plant roots in contact.
3: Mycelium invades roots and lower stem.
4: Rhizomorphs grow in wood of roots of new plant, spreading and growing under bark.
5: Fungus hyphae spread internally rotting the roots and stem, girdling trees causing die back. Toadstools can appear in early autumn around base of infected plant.

SPREAD: The fungus spreads underground by direct contact between the roots of infected and healthy plants and also by means of black, root-like structures called rhizomorphs (bootlaces), which can spread from infected roots through soil, usually in the top 15cm but as deep as at least 45cm, at up to 1m per year. It is this ability to spread long distances through soil that makes honey fungus such a destructive pathogen, often attacking plants up to 30m away from the source of infection.

CONTROL: Physical – Excavate, remove and dispose of infected plants including as much of the root system as possible.
Cultural – When honey fungus is found plant only species that show resistance eg: Taxus Spp. and Lavandula Spp.

Question 47

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

ROSE BLACKSPOT

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 47

ROSE BLACKSPOT (Diplocarpon rosae)

DAMAGE: Fungal disease causing black spots/lesions on foliage of rose plants. If not controlled can result in entire defoliation of plant. Symptoms are dark coloured (brown to purple-black) leaf spots that form on upper part of the leaf surface which gradually turn yellow and drop of the plant. Raised reddish-purple spots or lesions can form on the rose canes.

SPREAD: Mycelium on spots bears tiny conidia (conidial pustules) which are freely spread from diseased to healthy leaves all through summer, especially in damp weather which gives them every opportunity to germinate.

CONTROL: Physical – Gather up and dispose of fallen leaf litter in the autumn, by pruning and removal of infected canes with stem lesions in the spring before foliage develops. This will slow the development of the disease but spores can still infect as may be windblow from outside of locality.
Chemical – Systemic fungicides eg: Tebuconazole (fungus fighter concentrate) can be used. Some fungicides may contain insecticides and should only be used where there is a pest problem also.

Question 48

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

POTATO/TOMATO BLIGHT

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 48

POTATO/TOMATO BLIGHT (Phytophthora infestans)

DAMAGE: Blight is a disease caused by a fungus-like organism which infests and develops rapidly in the leaves, tubers and fruit of potatoes and tomatoes in damp wet weather, resulting in collapse and decay of the plants. Blight is specific to tomatoes and potatoes, ornamentals related to Solanum are also attacked. On Solanum tuberosum (potatoes) blight is a rapid spreading wet rot of leaves which soon collapse, shrivel and turn brown, a fine white fungal growth can be seen surrounding the edges of the lesion on the lower side of leaves. The disease eventually reaches the tubers which causes a reddish-brown decay under the skin, they with be firm at first but soon develop into a soft rot. Symptoms on Solanum lycopersicum (tomatoes) leaves and stems is very similar, brown patches on green fruits may develop while mature fruits will decay rapidly.

LIFE CYCLE:

1: Infective spores are released into water and need to swim in a water film before settling on the plant surface and penetrating into the leaf tissues.
2: Disease spreads rapidly killing plant cells. When wet, stalks bearing the spores grow from freshly killed tissues and the disease can spread rapidly through the crop.
3: Lesions and fungus develop on plant.
4: Sporangia formed on diseased parts of plant.

SPREAD: Infections in garden occur via wind-blown spores from other plants. Potato blight overwinters in remaining rotten potatoes left in the soil or by the sides of fields. The fungus can also produce oospores (resting spores) in plant tissues that can contaminate the soil.

CONTROL: Chemical – When wet weather is forecast from June onwards, protectant fungicide sprays are a sound approach for outdoor grown tomatoes.
Cultural – Early planted and early harvested potatoes can escape infection.

Question 49

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

CLUB ROOT

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 49

CLUB ROOT (Plasmodiophora brassicae)

DAMAGE: Above ground causes poor growth, poor colour, pale and chlorotic with smaller sized plants and wilting on warmer days. Underground the roots are badly affected – thickened, irregularly swollen areas distorting the normal organisation and shape of the roots. Caused by a slime mould – a fungus which is soil-borne and persistent over many years that attacks vegetables such as cabbages, broccoli, cauliflower and radishes. There is no toadstool or visible fungus organism or hyphae.

LIFE CYCLE:

1: Enters host plant via root hairs.
2: Generates disorganised and rapid growth of the affected tissues causing swelling, made worse by moist soil and low acid pH.
3: Resistant spores of the fungus are generated in the damaged ‘clubbed’ tissues.
4: On breakdown these spores are released into the soil where they remain active for a decade or more.

SPREAD: As resistant spores are long lasting, contaminated soils can be moved by wind or water thus acting as an infection source for adjacent areas.

CONTROL: Cultural – Badly infected soils are not suited for brassica growing. Crop rotation programme based on a 4 year rotation.
Chemical – Use of a suitable fungicide applied to the transplant irrigation water or applied before or at planting time can help to reduce development of the disease.

Question 50

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

HOLLYHOCK RUST

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 50

HOLLYHOCK RUST (Puccinia malvacearum)

DAMAGE: Fungal disease that attacks Alcea (hollyhock) and Malva (mallow) species. Undersides of leaves are usually heavily infested with bright yellow to orange-red rust-like spots with the associated yellowish larger spots on the upper leaf surface. Disease steadily develops completely covering most of the plant, the leaves dropping off especially at the bottom of the plants. In extreme infections stems are steadily infected gradually causing the whole plant to die.

SPREAD: By air-borne spores.

CONTROL: Cultural – Essential to remove infected leaves from plants as soon as fungus is noted. In the dormant season remove any infected leaves and dispose of away from the garden as these will provide a source of re-infection of the fungus when new growth begins. Weeds such as Malva can carry rust so is imperative to remove these if they are seen in the garden.
Chemical – Using a systemic fungicide at 14 day intervals in the early spring into summer.

Question 51

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

APPLE AND PEAR CANKER

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 51

APPLE AND PEAR CANKER (Nectria pirina & Nectria galligena)

DAMAGE: Fungal disease that affects range of woody plants including Malus Spp. (apples) and Pyrus Spp. (pears). Generally attacks and infests the stems and shoots of apples, causing shoots to become girdled and ultimately killed. Initial indicators of canker infection are reddish-brown spots around leaf scar, spur or pruning wound usually in late spring or early summer. Canker develops quickly with ring shaped cracked forming in the bark. Where canker girdles the trunk or branch, the shoots above the canker site die and canker usually stops developing after one year. Early symptoms are dead, leafless twigs or shoots often bearing small unhealthy leaves.

SPREAD: Spores from new cankers are transmitted by rain or overhead irrigation. Old mature cankers produce airborne spores that can start an infection at a distance away from the source. Airborne spores will begin new infestations, water-borne spores will increase the disease levels in trees already infected.

CONTROL: Physical – prune out diseased wood and remove badly affected trees.
Chemical – Fungicidal sprays eg myclobutanil used against apple scab or powdery mildew give incidental control of canker.

Question 52

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

FIREBLIGHT

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 52

FIREBLIGHT (Erwinia amylovora)

DAMAGE: Bacterial disease that enters host plants like Malus and closely related species via injuries or physical entry points with soft tissues such as flowers. Flowers will wilt and turn back, foliage looks black and scorched with shoot dieback. Underneath the bark is stained a reddish-brown and cankers my overwinter the infection. If the infection reaches the trunk the tree will be killed.

SPREAD: Bacteria are transmitted by wind-blown rain and insects.

CONTROL: Physical –Remove infected parts. Infected wood is stained red below the bark, prune back into healthy wood at least 30cm below infection point, 45 cm for thicker stems.
Cultural – Grow resistant varieties where possible.

Question 53

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

BACTERIAL CANKER OF PRUNUS

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 53

BACTERIAL CANKER OF PRUNUS (Pseudomonas syringae pv. Morsprunorum & P. s. pv. syringae)

DAMAGE: Bacterial disease caused by two closely related species of bacteria that infect the stems and leaves of Prunus, especially plums and cherries. Causes sunken lesions of dead bark and small holes in the leaves after brown spots fall out, known as ‘shothole’. Cankers begin to develop in mid-spring and soon afterwards shoots may die back. Shot-holed foliage is seen from early summer. As this disease has a large number of pathovars affecting a range of different yet specific hosts, disease resistance might be more easily overcome by the bacterium with time.

LIFE CYCLE:

1: Bacteria colonises the foliage and in wet weather in spring or early summer enters the leaves through the stomata, infecting young leaves.
2: As the leaf matures these infections cease to expand and are revealed as small patches of dead tissue. As the leaf expands fully, the live tissues pull away from the dead patch, which drops out, leaving a ‘shothole’.
3: Cankers develop when the bacterial cells gain entry through wounds or leaf scars at the time of leaf fall. Cankers remain more or less dormant through summer, when tissues are resistant, and during autumn and winter when temperatures are low.
4: In spring, the infections spread rapidly, killing the bark.

SPREAD: Bacterial canker infections occur during fall, winter and early spring (during cool, wet weather) and are spread by rain or water and pruning tools. The bacteria overwinter in active cankers, in infected buds and on the surface of infected and healthy trees and weeds.

CONTROL: Physical – Prune in July or August when tissues are most resistant, remove cankered zones pruning back to healthy wood and burn infected parts away from growing area.
Cultural – Grow varieties that show some resistance eg ‘Merton Glory’ Cherries.

Question 54

(4. 1) Describe the damage caused by:
(4. 2) Decribe in outline the life cycle of:
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

POTATO LEAF CURL VIRUS (AND VECTOR PEACH POTATO APHID)

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 54

POTATO LEAF CURL VIRUS (AND VECTOR PEACH POTATO APHID)

DAMAGE: Generally will not kill the plant but causes a loss of yield adding to the decline of potato as a crop plant. Leaves curl upwards, affected plants are dwarf with very fragile leaves and whole plant it light in colour an etiolated.

LIFE CYCLE:
1: Overwinters in infected seed potato tubers and in perennial solanaceous (nightshade) weeds.
2: Peach potato aphids feed on infected weeds and take virus into their gut.
3: Aphids feed on crop plant transmitting the virus and crop plant becomes infected.
4: Aphids feed on crop plant and transmit to perennial weeds where it over winters
SPREAD: Spread by several aphid species that colonize potato, with the peach potato aphid being the most efficient. The insect vector is essential to spread because mechanical transmission, like that which occurs when the leaves of an infected plant rub on a healthy one, does not occur with PLRV.

CONTROL: Chemical – Insecticide for aphid control is critical against the spread of the virus with peach potato aphids being the primary method of infection.
Cultural – There are no immune varieties though some cultivars show good resistance to the virus, use only certified seed potatoes as these have a low pathogen infection guaranteed by state certification procedures.

Question 55

(4. 1) Describe the damage caused by:
(4. 2) NOT REQUIRED
(4. 3) Describe the methods of spread of:
(4. 4) Describe TWO different methods of minimising the effects (including prevention) of the disease; methods should be selected from more than one of the control options available (chemical, physical, cultural)

TOBACCO MOSAIC VIRUS (TMV)

(NOTE: Due to the lenth of the list of the diseases and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 55

TOBACCO MOSAIC VIRUS (TMV)

DAMAGE: Results in the mottling or distortion of the leaves and fruit of affected plants stunting growth and poor quality and yield of fruit. Causes yellowing of outer leaves, brown splitting, necrotic collapse (blackspot and death of the youngest leaves) and much bronzed, stunted and crinkled older plants.

SPREAD: Aphid vector that aids transmission of the virus from an infected plant to an uninfected plant.

CONTROL: Physical – Any plant showing signs of spotted wilt should be destroyed as soon as the first symptoms are seen.
Chemical – Insecticide for aphid control

Question 56

(4.4) Explain how the knowledge of the life cycle and biology of diseases named in 4.2 contribute to the success of their control.

Answer 56

In order to have an infectious plant diseases, three things are requires; susceptible host plant, A pathogen and a favourable environment for disease development which make up the ‘disease triangle’.
Understanding this basic principle about infectious plant disease is an important relation to developing successful disease control methods. Many cultural practices that are useful in disease management are directed toward changing or creating an environment that is less conducive to disease development.

There are a number of stages in the development of a disease and it requires of these steps to reach and successfully infect a host plant, any interruption in the process results in the disease not being successful. The role of treatments is often to block the success of one or more of these steps.

Question 57

(4.4) Describe TWO methods of avoiding the spread of plant viruses.

Answer 57

Keep gardens weed-free, as weeds can be reservoirs of virus infection for garden plants.

Do not propagate from any plant suspected of virus infection.

Question 58

(5.1) State what is meant by the term ‘plant disorder’.

Answer 58

A physiological disorder is a disturbance in the normal function of the processes within the plant eg: one involving the cells of the plant and the processes that take place within the plant like photosynthesis and respiration.
These disorders are all a direct result of the environments in which plants grow, the cannot be associated with any pest or disease causing organism. They are not infection and one affected plant cannot pas it to another however the environment that triggers the disorder in one plant may also trigger the disorder in another plant in the same growing area.

Question 59

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

FROST

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 59

FROST

HOW PLANTS AND GROWTH ARE AFFECTED:
Varied affects with plant species, ages, hydration level, water content, overall health level and stage of growth. Young, actively growing, flowering or dehydrated plants along with thin-barked woody and herbaceous plants will be most liable to injury from freezing temperatures. Winter hardy plants need acclimatisation to colder and freezing temperatures which begins with the shortening autumn days and gradual lowering of temperatures, if a very cold freezing period of temperature occurs when there has been no previously cold or gradually colder weather to harden-off the plant tissue the damage will be more extensive.
Frost damage includes distorted leaves, flowers, buds and shoots which may even blacken. In severe frost crack injury to the cambium may develop. Frost ribbing can occur when a previous wound is repeatedly damaged in successive years.

AVOIDANCE:
Planting out of indoor sown plants once they have been hardened off and protect further with newspapers, polytunnels or cloches.

Question 60

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

SHADE

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 60

SHADE

HOW PLANTS AND GROWTH ARE AFFECTED:
Low light levels result in poor growth, pale leaves and even death. Plants grown in the absence of light are said to be etiolated meaning they lack chlorophyll; they are tall and spindly with long internodes and have small leaves that have failed to expand.

AVOIDANCE:
Providing supplementary lighting in winter when the day length is shorter, frequent cloud cover and the low light intensity caused the low-lying sun.

Question 61

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

DROUGHT

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 61

DROUGHT

HOW PLANTS AND GROWTH ARE AFFECTED:
When shoots fail to access enough water drought symptoms include: a check to growth, wilting foliage, stems and buds and dieback. Woody and perennial plants can suffer from drought symptoms after prolonged periods of days in waterlogged soil or in areas with a high water table, the roots die off and plants grow poorly, wilt in a warm spell and die back if there is a period of drought from lack of re-established roots.

AVOIDANCE:
It is helpful to have a deep, water holding topsoil in good order and with good drainage, when setting out plants, plant them firmly in the proper natural depth and water them in.

Question 62

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

WATERLOGGING

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 62

WATERLOGGING

HOW PLANTS AND GROWTH ARE AFFECTED:
Excess water causes anaerobic soil conditions which leads to dieback. Symptoms include; leaf chlorosis, defoliation, reduced leaf size and shoot growth, early autumn colouration and leaf drop.

AVOIDANCE:
Ensure plants grown in containers have unblocked drainage holes for surplus water to speedily drain away and should not be left to stand in water.

Question 63

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

HIGH/LOW TEMPERATURE DAMAGE

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 63

HIGH/LOW TEMPERATURE DAMAGE

HOW PLANTS AND GROWTH ARE AFFECTED:
Excessive sun and the accompanying heat can cause a range of problems. High temperature damage mostly occurs on the south side of plants which can cause issues especially for trees. Plant responses to high temperatures include; potential chlorophyll denaturing (solarisation of chlorophyll), physical scorch of plant tissues, flower and flower bud desiccation and desiccation of younger growing shoots in some species if high temperatures are associated with low water availability.
General chilling injury symptoms are common to other stress affects which can make it difficult to identify correctly including internal discolouration, surface lesions, sunken areas and surface discolouration, and slowed growth though this is difficult to detect without non-chilled plants to compare with.

AVOIDANCE:
Use shade cloth/mesh to shade and protect plants from intense light and heat especially in glass houses in summer.

Question 64

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

SOIL PH INCLUDING THE SYMPTOMS OF LIME INDUCED CHLOROSIS

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 64

SOIL PH INCLUDING THE SYMPTOMS OF LIME INDUCED CHLOROSIS

HOW PLANTS AND GROWTH ARE AFFECTED:
A lack of iron (Fe) availability from the soil to the plant causes an iron deficiency causing a disorder defined as lime induced chlorosis. Iron tends to gradually become unavailable for plant uptake if the soil pH is outside the range of 5-6.5 often being a problem if the soil is too alkaline (above 6.5). Iron deficiency can also occur in waterlogged soil, if fertilisers have been applied too heavily or if other nutrient concentrations like calcium and zinc in the soil are too high.
Iron is required for synthesis of chlorophyll for photosynthesis and because of this deficiency of iron causes chlorosis in the younger foliage as it is immobile in the plant. Young foliage becomes yellow or brown in the leaf margins between the veins which stand out green, fruit will be of poor quality and low yield.

AVOIDANCE:
Avoid planting susceptible plants on soil with a high pH, Rhododendrons, Azaleas and Camellias are all calcifuges (acid loving plants) and do not do well in alkaline soil.

Question 65

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

FASCIATION

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 65

FASCIATION

HOW PLANTS AND GROWTH ARE AFFECTED:
Fasciated stems are produced due to abnormal activity in the growing tip of the plant. Often, an abnormal number of flowers are produced on affected stems. Normal branches may arise from fasciated stems
Ring fasciation is where a ring of flowerheads are produced around a normal central flower, a phenomenon referred to as ‘hen and chicks’. Symptoms include flattened shoots, shoots that appear to be composed of several fused shoots, flattened elongated or misshapen flower heads with numerous flowers.
Fasciation may be caused by random genetic mutation or disruption, the bacterium Rhodococcus fascians, Viral infection, damage to the plants by frost, animals (including insects), chemical or mechanical injury – even hoeing or forking around the plant have been implicated. Some plants are more commonly infected such as Euphorbia and Digitalis.

AVOIDANCE:
Affected parts of shrubs and trees can be pruned out if desired. Fasciation seldom recurs on herbaceous plants the following year.

Question 66

(5. 1) Describe how plants and their growth are affected by:
(5. 2) State ONE method of avoiding EACH of the disorders described in 5.1:

ROSE BALLING

(NOTE: Due to the lenth of the list of the disorders and required information for each answer I have combined the questions and answers for each one under each disease name)

Answer 66

ROSE BALLING

HOW PLANTS AND GROWTH ARE AFFECTED:
Flower balling is a disorder in which flower buds develop normally but do not open. Caused by cool, wet weather saturating the outer petals and then the sunshine drying and fusing them into a tight, papery shell, preventing the bud from opening.
Flower-balling is characterised by the following appearance: the bud often feels soft and slimy to the touch; and then the outer petals turn brown, becoming dry and crisp in places, when the outer petals are prized apart, the inner petals appear normal, the bud may drop off or, if it hangs on the plant, grey mould may develop and cause it to rot. Thin-petalled, double flowers such as rose, peony and camellia cultivars are most susceptible to this condition

AVOIDANCE:
Good air circulation is important to allow the buds to dry quickly, when planting roses chose an op site but not exposed. With existing planting increase ventilation by pruning correctly.