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Question 1

Describe two named protected structures used in horticultural crop production

Answer 1

Greenhouse : Permanent structure which is designed for growing plants in. The framework can be made from aluminium and it is clad with horticultural glass or other transparent materials e.g. twin walled polycarbonate to maximise natural light entry

Cold frame : low box-like structure with wood or brick sides. It is covered by ‘lights’ i.e. glass or twin walled polycarbonate enclosed in a wooden frame

Question 2

Describe the suitability of a structure for the production of a main season tomato crop

Answer 2

A greenhouse is a tall structure which is able to accomodate a tomato crop. It is economic to heat and will allow a tomato crop to be grown economically. Thhe structure of a greenhouse is strong enough to enable a crop of tomatoes to be layered and has excellent light transmission to maximise quality and yield of the crop. A greenhouse can also be easily ventilated.

Question 3

Describe the difference between the environment inside and outside of a named protected structure containing a crop under the following:

natural light / relative humidity / carbon dioxide

Answer 3

Greenhouse

Natural light

Outside : Ambient light levels

Inside : Lower than ambient light levels due to shading of the structure and cladding material used

Relative humidity

Outside : lower relative humidity due to wind/rainfall/air temperature.

Inside : higher relative humidity with less fluctuation due to transpiration or loss due to evapotranspiration

Carbon dioxide

Outside : ambient levels of carbon dioxide

Inside : lower levels of carbon dioxide due to uptake by crop

Question 4

Describe the production of Chrysanthemum x morifolium under the following:

propogation / maintenance/cultivation

Answer 4

Propogation

by softwood, tip stem cuttings approximately 100mm in length. They are prepared by making a clean cut just below a node, and removing the lower third of leaves (leave 4-5 leaves on the stem). A mild hormone rooting powder is applied to the base of the cutting / the cuttings are rooted in a close case with basal heat at a temperature of 21-24 which takes approximately 2-3 weeks

Once rooted the cuttings are planted in slightly raisd beds in the border soil / the plants are pinched out once they are established to encoruage lateral growth to produce a spray of chrysanthemums / the plants are supported by nets which are held by posts driven into the soil around the bed and raised as the plants grow

Maintenance/cultivation

a range of tasks are carried out e.g. stopping the plants by removing the apical bud just above a node to encourage lateral growth. Disbudding i.e. removal of lateral buds by rubbing them out to leave the terminal bud. Irrigation can be applied by suing a drip or capillary irrigation system to provide moisture to the growing media and to avoid wilting. A high level of nutrition is required and can be applied as a base dressing or as a liquid feed through the irrigation system

monitor for pests (red spider mite) and diseases (botrytis) / onces established will require regular watering / top dressing of a high K fertiliser is advantageous for when flower buds are forming

Question 5

Describe a named pest and disease of Chrysanthemum x morifolium

Answer 5

Pest : Red spide mite cause localised deeeath of the leaf mesophyll cells due to the piercing and sucking activity of the mite. This results in fine mottling of the leaf. In large numbers the mites can kill leaves and in severe infestations fine silk strands are produced.

Botrytis : fungal disease which affects soft tissue e.g. leaves, non woody stems and the flower buds of Chrysanthemum x morifolium. It is seen as a fuzzy grey mould which is prevalent in cool or humid conditions.

Question 6

State factors to consider when selecting a container for an interior display

Answer 6

The amount of maintenance required to keep the container in a good condition

How watertight the container is to avoid it damaging flooring

The weight of the container when moving it into position

Selection of a container which is suitable for its surroundings and its’ aesthetic appeal

type of material used to manufacture the container and its likely life span

size of the container with reference to the plant and time span before it requires potting on

position where the container is going to be placed

method used to irrigate the container

the colour of the container

the container should be balanced in terms of size and shape

the container should enhance the planting

Question 7

State one biological control for pests of protected crops

Answer 7

Encarsia formosa is a parasitic wasp to control glasshouse whitefly

Phytoseiulus persimilis a predatory mite to control glasshouse red spider mite

Question 8

State the benefits and limitations for controlling pests in a protected environment under the following:

chemical / biological / cultural

Answer 8

Chemical

Benefits : Effective control if correct chemical at correct rate has been applied / does not rely on the establishment of a natural parasite or predator

Limitations : Resistance build-up can occur in pests / period of time before an edible crop can be harvested and marketed

Biological

Benefits : Avoids the build-up of chemical residue in crops and the environment / extended periods of balanced pest control will be achieved if the parasite or predator is balanced with the pest

Limitations : Biological control agents never totally eradicate the pest problem / use of biological control agents limits the range of other control measures

Cultural

Benefits : No pesticides are used which is better fo the environment / as not pesticides are used there is no clearance period before the crops can be sent to market

Limitations : May not eradicate the pest / May no be an option if the pest is well established on the crop

Question 9

State the practical considerations when considering energy sources for a protected structure

Answer 9

Electricity : the availability of electricity to the site. The heat produced by electricity can be controlled by a thermostat but it produces dry heat that will not raise the relative humidty in a protected structure

Gas : a mains gas supply may not be available necessitating the use of bottled gas. If combustion of the gas is poor it may lead to toxic gases being released e.g. nitrogen dioxide. Moisture will also be given off during combustion which will raise the relative humidity

Question 10

State the benefits of temperature control when growing crops in a protected structure

Answer 10

Extended period of cropping maintains continuity of supply

Ability to grow an extended range of crops and cultivars

Improved quality of production

maximum yield due to optimum health growth

Control over crop timing and harvesting period

Reduced pest and particularly disease problems

Question 11

Describe a distinct horticultural use for the structures:

greenhouse / cold frame / polythene tunnel / cloche / conservatory

Answer 11

Greenhouse : used for the propogation and production of a long main season crop of tomatoes or the production of a cut flower crop

Used in crop production: heated or non-heated environment to grow vegetable or ornamental plants e.g. tomatoes, cucumbers, Poisettias, Cyclamen / crops can be grown on benches or on the ground using a hydroculture system

Cold frame : used for the propogation and production of young vegetable crops e.g. cabbage and for hardening off bedding plants

Polythene tunnel : used for growing a self-blanching celerey crop or for the production of a crop of lettuce

Used in crop production: normally non-heated / less flexible growing structure compared to glasshouse / potential of the growing season is shorter and retains a high level of humidity / used to grow celery, strawberries , rasberries, peppers and lettuce

Cloche : used to advance ripening of crops e.g. strawberries or for covering taller crops to get them established

Conservatory : used to display flowering or foliage pot plants for the home

Question 12

Describe the establishment of a crop of bedding plants under the following:

seed sowing / germination environment / pricking out

Answer 12

Seed sowing

small seed can be sown broadcast in a seed tray whereas large seed can be space sown in a seed tray or sown in modules. Seed trays are overfilled with a seed growing media and firmed with a presser board to create a firm level seed bed. Seed is broadcast evenly at a suitable density and lightly covered with growing media as appropriate

Germination environment

Seeds require moisture, oxygen and warmth to germinate which can be provided by well aerated but moisture retentive seed sowing growing media and a temperature of 16-18degree C in a greenhouse or growing room

Pricking out

Carried out once the cotyledon leaves have expanded and can be handled without damage. The seedlings are teased apart with a dibber and pricked out into seed trays, modules or small pots containing a suitable gorwing media e.g. John Innes No. 1. A hole, large enough to accomodate the root system of the seedling is made using a dibber and to a depth so that the cotyledon leaves sit just above growing media level

Question 13

Describe two effects on plant growth for the following environmental factors:

Good air movement / higiht natural light / high relative humidity / erratic irrigation / carbon dioxide concentration

Answer 13

Good air movement : Sturdier growth / less prevalence of disease

High natural light : Compact healthy growth with short internodes / good bud initiation and flower development

High relative humidity : higher incidence of disease / less water loss, reduced irrigation required

Erratic irrigation : Possible splitting or damage to fruit production / possible leaf damage caused by leaf scorch or root loss

Carbon dioxide concentration : If concentration of carbon dioxide is good, rate of photosynthesis will increase / higher level of crop productivity

Question 14

State the importance of each of the following in relation to protected cropping

framework material / orientation / supplementary lighting / cladding material / shape of the structure

Answer 14

Framework material : this needs to provide strength as it is the skeleton of the structure. The can be made from wood e.g. red cedar or teak. Metal can also be used e.g. steel which can be dipped in zinc to protect it from corrosion i.e. galvanised.

Orientation : this is the way in which the structure is aligned in relation to the points of the comopass. An Easr/West orientation is most desirable as it will present the maximum amount of glass to the sun and will maximise natural light entry which is especially important in the winter months

Supplementary lighting : is artificial lighting which is used within a protected structure to supplement the natural daylight available within the structure. A range of lights cna be used e.g. high pressure sodium or metal halide lamps

Cladding material : thiss is the material that covers the sides of the roof of the structure. It is attached to and covers the framework of the structure e.g. horticultural glass or polycarbonate

Shape of structure : this will affect access by people and machinery as well as natural light transmission especially during the winter months. A mansard shape which has a roof in two stages and sloping sides will provide the best angle for light transmisiion if light strikes the glass at an angle of 90 degrees, 90% of the light will be transmitted.

Question 15

Describe the production of Kalanchoe blossfeldiana under the following:

potting and re-potting / watering / feeding / control of named pest

Answer 15

Potting and repotting

plants are potted into 9cm pots when they are rooted using a growing media e.g. John Innes No. 1. All pots and media need to be sterile and plants should be graded and any damaged material removed. The plant should be potted upright in the centre of the pot to a level just above the top of the roots and firmed. Re-potting into e.g. a 1 litre pot using John Innes No. 2 will take place once the plant roots have filled the orginal pot. A multi-purpose growing media would also be suitable.

Watering

will be required when the potted plant is light when lifted or the growing media has shrunk away from the edges of the pot. The plant can be watered overhead or by capillary watering moderately during the growing season and just kept moist during the winter.

Feeding

is required to ensure that the plant has an adequate supply of nutrients for growth e.g. N, P, K. This can be provided by the inclusion of a compound controlled release fertiliser in the growing media or applied as a liquid feed through the irrigation system

Control of named pest

e.g. aphids or mealy bug can be controlled by the use of soft soap or by the practice of good crop hygiene and providing optimum cultural conditions for the plant

Question 16

State one distinct benefit and limitation for the following materials used for plant production containers:

Terracotta / plastic / polystyrene / peat / paper

Answer 16

Terracotta

Benefit : heavy material compared to plastic which provides stability

Limitations : It is expensive compared to plastic

Plastic

Benefit : Durable, long lasting and available in many different colours / waterproof / lightweight

Limitations : Watering is more critical as the material is impervious / becomes brittle with age when exposed to light

Polystyrene

Benefit : Very light weight. White in colour reflecting light back onto the plant

Limitations: Very fragile and can be easily damaged / hard to dispose as non-recyclable

Peat

Benefit : Natural material. Pot can be plunged into soil to avoid root disturbance at planting stage

Limitation : Limited used. Not eco-friendly in the slightest / difficult to re-wet when it becomes dry

Paper

Benefit: Inexpensice compared to all other materials

Limitation: very short term use

Question 17

Describe the effects of air temperature on a growing crop and how it can be controlled

Answer 17

Low air temperatures will slow down growth and photosynthesis. More extreeme low temperatures can cause frost damage. Temperatures that are too high will also reduce the rate of growth

Can be controlled by using a combination of heating during the winter months to maintain an optimum temperature and the use of ventilation or damping down during the summer to lower the temperature

Question 18

Describe the effects of relative humidity on a growing crop and how it can be controlled

Answer 18

High relative humidity can increase the incidence of fungal problems. Water and nutrient uptake can also be reduced. Low relative humidity will increase the rate at which plants dry out.

Can be controlled by providing ventilation to lower the relative humidity or by raising the temperature. Relative humidity can be raised by damping down the floors inside the protected structure or by reducing the air flow

Question 19

Describe the production of a main season tomato crop for the following:

Propogation / planting and establishment / maintenance

Answer 19

Propogation

Tomatoes are propogated by seed either broadcast in a seed tray or modular trays with one seed per module using seed sowing compost, e.g. John Innes. They are germinated at a temperature of 18-23 and pricked out into modules 9cm pots. They must be handled carefully by the hypocottyl to avoid damage and moisture must be maintained.

Planting and establishment

The growing method will determing the way in which the tomatoes are planted. Points to consider include: depth of planting. firmness, careful handling and grading of plants to maintain uniformity. Supporting strings can be tied to the base of the plant and suspended in the structure

Maintenance

Involves stringing the plants to allow for stem growth, deleafing the lower leaves to allow the tomatoes to ripen and increase air movement to avoid fungal diseases. Side shoots are also removed to maintain a single growing point and watering and feeding are carried out as required. Relative humidity can be reduced by providing ventilation which will also maintain the ambient carbon dioxide concentration / high potash feed to encourage flowering and fruiting

Question 20

Describe the production of Saintpaulia ionantha for the following:

potting up - from a leaf petiole cutting / watering / feeding / repotting / sympton and control of a pest

Answer 20

Potting up - from a leaf petiole cutting

Young plantlets must be potted up into 9cm pots separately to avoid a multi crown plant using an appropriate potting compost e.g. John Innes No. 1. Also need to consider the depth of the potting (do not bury the central growing point of the plant), centralising the plant in the pot, handling the plant with care to avoid damage and watering the plant in to settle the compost around the root system without wetting the foliage

Watering

Water from below to avoid scorching the hairy leaves. The plant will take up water by capillary action as required. Alternatively a drip system can be installed in the pot below the canopy of the foliage / provides a higher relative humidity / keep moist especially during the growin season / Rain water or soft water is preferable to avoid a build up of lime in the pot

Feeding

Can be fed using a range of methods, A base dressing can be included in the potting compost to provide a range of major and minor nutrients to be released over a period of time as the plant grows e.g controlled release fertiler such as Osmocote. The plants can also be liquid fed (immediate release e.g. Miracle grow) through the irrigation system which could contain specific nutrients e.g. K to encourage improved flowering.

Re-potting

carried out when plant is potbound / repotted into pot one size larger with JI2 growing media / plant carefully knocked out of the pot, roots teased out and any dead or diseased foliage is removed / plant placed in the centre of the largeer pot and new growing media is gently firmed around it to ensure that it is at the same height as in the previous pot / don’t bury the crown of the plant

Pest and control

Vine weevil larvae : eat roots and stunt growth. wilting and chlorosis as the root system is destroyed

Control : biological controll pf a parasitic eelworm Steinernema kraussei / watered into moist pots from August to September after the adult has stopped laying eggs / keep pots moist for 2 weeks after application to ensure that all the larvae has been killed

Question 21

State the differences between the aerial environment inside a cropped protected structure compared with that outside for:

air temperature / air movement / relative humidity (on a sunny day) / natural light levels / carbon dioxide concentration

Answer 21

Air temperature

Inside a cropped structure : generally higher and can be effectively controlled by the use of ventilation and heating / the occurrance of very low temps in a structure is less likely although an air temp. below 0 can happen

Outside : the temperature will vary according to the seasons of the year / generally lower than inside

Air movement

less air movement within a cropped structure as there is no wind it can be controlled by the grower by the use of ventilation. Convection currents take place as the structure warms up naturally

Relative humidity

Lower relative humidity outside than inside

natural light levels

Higher light levels outside than inside

Carbon dioxide concentration

ambient carbon dioxide concentration levels compared to lower inside

Question 22

Describe the effect of high and low valuess of air temperature and air movement on plant growth

Answer 22

Air temperature

higher levels of air temperature usually encourage plant growth / every plant has a temp. range at which it will be able to produce optimum growth and excessively high air temps can also cause a slowing down of vital processes within the plant / leaf scorch can occur due to a temporary shortage of water in plant leaf cells

low air temps will slow down processeds in the plant e.g. photosynthesis and respiration and will result in reduced plant growth. Extreme reductions in air temperature can cause plant cells to freeze and subsequent cell collapse and death of the plant

Air movement

Higher levels will affect the amount of water loss from the foliage of the planr by transpiration which will affect the amount of water and nutrients taken up by the plant / excessive air movement can cause physical damage to the plant

lower levels of air movemnt will reduce the rate of transpiration which can affect the amount of nutrients taken up by the plant and the level of humidity around the plant

Question 23

State 4 factors that affect the amount of natural light entering a glasshouse structure

Answer 23

Orientation of the structure

Desgin of the protective structure

Cleanliness of the cladding material

Construction materials

Question 24

Describe how the orientation of the structure and its design can enable a grower to maximise natural light entry into a glasshouse

Answer 24

Orientation of the structure

The amount of natural light entering the structure is determined by the amount of glass presented to the sun / if the glasshouse is oriented east/west with the lonfest side facing ths sun the amount of light entering the structure will be maximised

Design of the protective structure

Most light will pass into a structure where the light strikes the glass at an angle of 90 degrees (angle of incidence) / by designing a mansard shaped structure or by raising the eaves as high as possible natural light entry into a glasshouse will be maximised

Question 25

Describe what is meant by supplementary lighting and give one example of its use

Answer 25

Supplementary lighting is artificial lighting which is used to supplement natural light / this provides an extension to the growin day during the winter months when the day length is shortened as well as additional lighting during the hours of daylight when there is insufficient light to achieve optimum growth

An early main season tomato crop may require supplementary lighting between potting and planting and early in the season when natural light is poor

Question 26

State 2 distinct characteristics of materials used in the manufacture of containers used in protected environments for:

polystyrene / plastic / peat / terracotta /recycled materials / paper / natural stone / reconstituted stone

Answer 26

Polystyrene : veyr lightweight and is a good insulator of heat and cold

Plastic : impermeable to water and becomes brittle when exposed to light

Peat : is very difficult to re-wet once it has dried out and is usually acidic

terracotta : plants will dry out quicker / may not be frsot resistant / heavy in weight

recycled materials : sustainable material / environmentally friendly

paper : lightweight / short life / minimises root disturbance at planting

Natural stone : very heavy in weight / expensive compared with other materials / aesthetically pleasing

reconstituted stone : can look veyr realistic / long life / less expensive tha natural stone

Question 27

Describe the production of a crop of cyclamen persicum for the following:

propogation and establishment / plant husbandry

Answer 27

Propogation and establishment

cyclamen is a large seed which has ahrd seed coat which can be softened by soaking for 12 hours prior to sowing. Seeds can be sown in individual modules or seed trays using a loam-based growing media such as John Innes seed compost / seeds germinated at 21-24 and should be kept moist but not wet

Once germianted a corm will begin to form - pot on using John Innes No. 1 - do not bury the corm

Plant husbandry

Plants can be grown on at a temp of 15-18 ensuring that they are well ventilated and kept moist by he use of capillary irrigation. Plants should be spaced so that the foliage is not touching and the can be fed with a balanced John Innes liquid feed as required with a higher level of K at the flowering stage / plants can be potted into a 14cm half pot using J I 3 compost as required

Question 28

Describe the damage caused by one pest that affects Cyclamen persicum

Answer 28

Vine weevil - the rounded larvae of vine weevil which have a brown head ear the roots - in severe infestations all roots are eaten and the plant collapses / it will also wilt in warm conditions due to the lack of roots

Question 29

State 3 mainf characteristics of growing media used for growing hose plants and explain why they are so important

Answer 29

growing media must have a good water retention capacity to maintain the turgidity of cells / without water nutrients cannot be taken up into the plant via the root system which are essential for plant growth

a good air to water balance must be maintained within the growing media to enable the plant to respire / oxygen is essential for aerobic respiration to take place within the place

growing media must have the ability to retain nutrients which are available to the plant for growth

Question 30

State the benefits and limitations of growing tomatoes in protected structure

Answer 30

Benefits

increased yield due to improved and controllable environmental conditions / improved quality due to controlled growing environment / longer cropping period (extended season) providing continuity of cropping / increased range of tomato types that can be grown / opportunity to use biological control more easily

Limitations

increased cost of production, heating cost of structure etc… / increased speed of establishment of pests and diseases / all irrigation has to be provided / more attention to crop husbandry is required / less natural pollination whicih may necessitate the introduction of bees and agitation techniques on specific crops

Question 31

Describe two disorders that can damage a tomato crop

Answer 31

Blossom end rot : caused by a calcium deficiency / leads to breakdown of the cell walls leading to browning of internal tissues / young plants may become chlorotic and the fruit may start to go brown and rot /

controlled by ensuring plants are not fed excessiv elevels of K and they are watred regularly to prevent drought stress / ground limestone or calcium hydroxide can be added

Fruit splitting : usually occurs when rapid growht is induced following overwatering after allowing the plants to dry out

controlled by ensuring that the growing media is water retentive and by regular and careful watering

Question 32

Describe one effect on platn growth and one control for the following environmental factors :

low light levels / overwatering / cold or freezing temps / low relative humidity / low carbon dioxide

Answer 32

Low light levels

Effect : etiolated growth / weak spindly growth

Control : provide supplementary lighting / improve light entry into the structure

Overwatering

Effect : root rot / symptons of oedema

Control : check for water requirement / use of a moisture meter / soil tensionometer

Cold or freezing temps :

Effect : dead cells / burst cells / collapse of part or all of plant

Control : provide protection e.g. bubble plastic or heating

Low relative humidity

Effect : excessive water loss / plants susceptible to red spider mite

Control : damp down the environment / reduce ventilation

Low carbon dioxide

Effect : slower growth rate / reduced photosynthesis

Control : provide ventilation / provide carbon dioxide e.g. propane burner

Question 33

Describe one method of heating including its distribution

Whys is this method beneficial?

Answer 33

A piped heatin system burns gas, oil or solid fuels outside the glasshouse and the heat is conveyed into the glasshouse by hot water / the heat is distributed around the glasshouse through the pipe and the cooling water returns to the boiler to be reheated

the heating can be regulated by a thermostat and can be distributed in small bore pipes which take up minimal space

Question 34

Describe the management of Ficus benjamina for the following:

propogation / potting / repotting / watering

What is a pest and control fo Ficus benjamina?

Answer 34

Propogation

propogated froms tem tip cutting / material that is healthy true to type and pest and disease free is removed from the stock plant jsut above a node approx. 7.5-10cm in length / cuttings are prepared by trimming just below a node at the base to a length of 5-7.5cm and removing the lower third of leaves / a mild hormone rooting powder can be applied to the base of the cutting but is not essential / cuttings places in a suitable environment e.g. closed case with a basal temp of 21-24 and high relative humidity to minimise moisture loss

Potting

pot into a 9cm pot once the cuttings have sufficiently rooted using a potting compost which is moisture retentive but well drained and contains a low level of nutrients e.g. JI1 / the rooted cutting is carefully removed from its tray and any damaged leaves etc,, are removed before placing it upright in the cente of the pot at the correct level (same level as was in cutting tray) and settingly the compost around the root system which is totally covered / do not bury the basal leaves / ensure the compost is gently firmed and the cutting is upright and secure

Re-potting

required once the plant become pot bound in the 9cm pot / knock out of the pot and tease out the roots to prevent root curls / pot into a 14cm pot using JI2 by placing the plant in the centre of the pot and to the same depth as the original root ball / following potting process as above

Watering

regular watering is requried depending on the environmental conditoins / it is important that the plant does not dry out and is kept near to container capacity / do this by watering overhead or using a capillary system / moist growing media should be maintained especially during the growing season by the use of a watering can with a fine rose, single spout or by placing the pots on a tray of water

Pest : red spider mite - localised death of the leaf mesophyll cells leads to fine mottling on the leaf / fine silk strands are also visible on the underside of the leaves in severe infestations

increase humidity / fatty acids / predatory mite Phytoseiulus persimilis

Question 35

Describe a manual method of irrigation and advantages

Answer 35

Watering can and a fine rose - can water above or below the leaf canopy depending on the circumstances and the growing conditions / the rose can also face down for a large droplet size or upwards for a fine spray / mains water or water from water butt can be used but hygiene must be considered

provides a limited amount of water before it needs to be refilled / the single spout can be used to water the base of a plant onto the root system / or with rose to provied a fine spray to a tray of seedlings

also hose pipe with fitted lance

Advantages : inexpensive / readily available and portable / adaptable and can be used to water large specimen plants or trays of seedlings

Question 36

Describe an automatic method of irrigation and limitations

Answer 36

Capillary system - consists of flooding a bed or bench with either sand or capillary matting where the plants determine how much water to take up by capillarity - this system can cope with a range of plants in different size pots

Drip irrigation system : alkathene pipes transport water from the mains near to the plant / capillary tube are inserted into the alkathene pipes which are often pegged into the container next to the plan / water is delivered as a drip from this tube which is targeted around the base of the plant / pipes smaller as get closer to plant / automated by use of a time clock

In hard water areas where the water is alkaline the fine capillary tubes can become blocked resulting in dry plants / rabbits or rodents can chew through the capillary tubes which can make them ineffective

Question 37

Describe a biological method of pest control in a protected structure

Answer 37

Encarsia formosa can control glasshouse whitefly / it is a parasitic wasp which lays its eggs in the immobile whiteful scales / within 10 days the whitefly scales go black / Encarsia formosa is usually supplied as parasitised whitefly scales containing the pupal stage of itself on the host plant leaves (usually tobacco) or stuck to a carrier card / these are placed amongst infested crops as soon as whitefly are found

Question 38

Why is a biological method of control particularly important?

Answer 38

pesticides are not used and is therefore more environmentally friendly as the biological control does not enter the water supply

as no pesticides are used there is no clearnace period which must be adhered to before harvsting and there is no-build up of chemicals on edible crops

as no pesticides are used there is no opportunity for the pest to build-up a resistance to the control method

there is no likelihood of the operator being poisoned if pesticides are not used and less training is required when using a biological control

as no chemicals are used there is no requirment to store and transport chemiclas and adhere to H and S regulations and no need for additional protective clothing

Question 39

Name a distinct protected structure suitable for the following and explain why

decorative display / crop production / plant propogation / overwintering plants

Answer 39

Decorative display

Conservatory - suitable for decorative disply as it is likely to be attached to the house which would enable the occupants to gain pleasure from the plants being displayed / it is also more likely that it can be heated efficiently

Crop production

Polythene tunnel - is suitable for crop production as it provides a warm, humid enviornment during the spring and summer for optimum growth / humidity is particularly suited to some crops e.g. self-blanching celery and courgettes

Plant propogation

Cold frame - is easily constructed and low cost protected area which is suitable for propogation by cuttings as not great height is required

Glasshouse - is suitable for overwintering plants as it has goof light transmission and can be heated to provide frost protection for tender plants

Question 40

Describe the characteristics of materitals suitable for the framework of a protected structure

Answer 40

Galvanised steel : is steel which has been dipped in zinc to protect it from rusting . it is very strong, heavy, difficult to shape and may rust where cut or bolted / it is usually used for structural supports and guttering of aluminium greenhouses

Aluminium : is lightweight and not strong enough for structural supports byt can be used for glazing bars / resistant to corrosion / low maintenance and does not retain heat well

Wood : Western Red Cedar is easy to cut and join, is warmer than galvanised steel byt has to be thick to be strong - this cuts out light which can result in a shadow effect / wood will eventually rot and can also warp

Question 41

Name two cladding materials suitable for protected structure stating a benefit and limitation

Answer 41

Horticultural glass

Benefit : good light transmission / long lasting / relatively easy to clean / does not deteriorate with age

Limitation : heavy to transport / very fragile and potentially dangerous / not easily cut / not flexible

Twin-walled polycarbonate

Benefit : provides excellent heat retention / easy to cut / will bend slightly / very light to work with

Limitation : more expensive than horticultural glass / degrades over time / less light transmission than glass / scratches

Question 42

How are glasshouses ventilated paying particular attention to airflow

Answer 42

Natural ventilation

cool, less humid air enters the glasshouse through side vents / hot air rises within the glasshouse and exits through the ridge ventilators

Fan ventilation

air enters through either a large fan or ventilator at one side of the glasshouse/structure / the air is drawn across the glasshouse and is expelled through a fan on the other side / this results in positive air movement across a crop and provides optimum ventilation

Question 43

Name flowering plants suitable for an interior display

Answer 43

Kalanchoa blessfeldiana / Narcissus Tete a tete / cyclamen persicum / Saintpaulia ionantha / euphorbia pulcherrima

Question 44

Describe the difficulties of maintaining plants for display in domestic buildings under the following:

temperature / light / pollution and dust / health and safety

Answer 44

Temperature

central heating produces a dry heat/low humidity and the temperature can fluctuate in differnent rooms depending on their aspect / this is difficult to overcome and can cause plants to wilt and produce stunted growth / the relative humidity can be raised by stnading plants in a tray of water

Light

Light levles can differe depending on the aspect of the rooms, the size of the windows and the season / plants may need to be moved according to the season to obtain greater light levels or supplementary lighting can be used / too high light levels will cause scorching of the leavs and too low light levels will cause spindly growth and etiolation and make plants more susceptible to attack from pests and diseases

Pollution and dust

pollution and dust can block the stomata on the underside of the leaves and coating the upper surafce / this reduces the plants’ ability to photosynthesise, looks unaatractive and affects plant growth / the foliage plants should be regularly cleaned/wiped to avoid a build-up of pollutants and dust

Health and safety

plants with spikes and thorns can be dangerous, especially to children / plants with poisonous parts can also cause allergic reactions / need to ensure that large plants and containers are stable and cannot fall over and cause injury

Question 45

State characteristics for the following cladding materials:

horticultural glass / polythene film / twin-walled polycarbonate

Answer 45

Horticultural glass

long life span, very heavy, strong but fragile / high level of light transmission / retains heat well

Polythene film

a lot less expensive than horticultural glass / limited lifespan of 4-5 years / does not retain as much heat as horticultural glass / good light transmission but reduced due to condensaton and deteriorates over time due to dust and UV rays

Twin-walled polycarbonate

more expensive / lighter in weight and is easier to handle than horticultural glass / sawn into shape and size / good heat retention and light transmission but may deteriorate over time due to acid rain

Question 46

State the properties of the following materials used in growing media for the production of plants in protected environments

shredded bark / perlite

Answer 46

shredded bark : non-clumping with an opens tructure and good aeration / bark can ock up nitrogen and has a lower water holding ability / the pH of the bark can be variable

Perlite : inert, durable, light and sterile / improves drainage and air-filled porosity in a growing media / water is only held on the surafce of the granule and it produces dust which is an irritant

Question 47

State the properties of the following materials used in growing media for the production of plants in protected environments

shredded bark / perlite

Answer 47

shredded bark : non-clumping with an opens tructure and good aeration / bark can ock up nitrogen and has a lower water holding ability / the pH of the bark can be variable

Perlite : inert, durable, light and sterile / improves drainage and air-filled porosity in a growing media / water is only held on the surafce of the granule and it produces dust which is an irritant

Question 48

Describe the environmental factors that must be taken into accound when displaying plants inside domestic buildings for:

natural light levels / air temperature

Answer 48

Natural light levels

will influence plant selection / poor light levels will result in etiolated growth, extended internodes and weak growth that is more susceptible to pests and diseases / plants with variagated foliage will require higher natural light levels to maintain their variagation / flowering plants will require good light levels while green foliage plants will tolerate lower light levels / excessively high light levels will result in leaf scorch

Air temperature

individual plants will require a specific temperature range / low temps will result in poor, weak, slow growth and lack of flower buds / excessively high temps will create additional drying out of the growing media and possible leaf damage / fluctuating temps are more dmaaging resulting in very poor growth and leaf damage

Question 49

Describe a protective structure suitable for each of the following:

sowing seeds / displaying tender perennials / growing sald vegtable crops / growing fruit crops / hardening off

Answer 49

Sowing seeds

glasshouse : usually clad in horticultural glass which has good light transmission and ventilation for plant propogation / the structure can be made from aluminium and galvanised steel supports / it can be heated

Displaying tender perennials

Conservatory : usually attached to the house / glazed to provide good light transmission / heating enables plants to be displayed year round

Growing vegetable crops

Cloche : traditonal ones are constructed from panes of glass and spring wire clips while others are made using galvanised wire hoops covered in thin polythene

Growing fruit crops

walk-in polythene tunnel : hoops made ffrom galvanised steel which are covered with a polythene ‘skin’ which will need replacing every 4-5 years / can be fitted with netting skirt to provide more uniform ventialtion / heating and irrigation can be installed

Hardening off

Cold frame : a low box which can be made from wood or brick and covered with ‘lights’ glass or polycarbonate covers) / frame sloping sides of 45 degrees for maximum light transmission / the cold frame does not have a base and can be positioned directly on the soil or a hard surface

Question 50

Describe the production of impatiens wallerian (bedding plant) for the following : propogation and establishment / growing media

Answer 50

Propogation and establishement

broadcast sown / evenly distributed in trays using seed compost and lightly covered / seeds germinate in closed case at a temp of 18-23 / once germinated and cotyledon leaves fully expanded the seedlings are pricked out into seed trays or modules / handle the seedlings by the cotyledons only to prevent damage to stems and use a dibber to avoid damaging the roots / plants grown at temp of 15-18 and water regularly to avoid drying out until they are ready to be planted out

Growing media

seed sowing media e,g J I which contains sand to provide good drainage but retains moisture and create adequate pore space for oxygen / the growing media is low in nutrients / when pricking out the seedlings into modular trays JI1 can be used which has more nutrients to enable the plants to sustain growth until they are planted out

Question 51

Describe the management for adiantum raddianum fern suitable for display in a domestic building for the following:

maintaining the optimum aerial environment / re-potting / watering

Answer 51

Aerial environment

stable temp of 15-18 is required with a relative humidity of 60-80% / this can be maintained by standing the fern in a larger tray filled with moist grit or by the use of humidifiers that atomise water directly into the air / ferns should be provided with diffused light and kept away from draughts

Re-potting

repot once become pot bound / do not over pot into a pot which is too large / remove any damaged or diseased fronds and tease out the roots if pot bound / repot into growing media containing a high organic content / place the fern upright, in the centre of the pot, no deeper than it’s previous level and backfill the growing media / firm carefully ro remove any larger air pockets

Watering

ideally use rainwater and water from the base or tepid water / ferns should never be allowed to dry out completely

Question 52

Describe a method for forcing Narcissus tete a tete

Answer 52

Prepared bulbs are potted at the end of September/early October into moistened bulb fibre / place containers in a cold, dark, moist environment e.g. cold garage or fridge at temp of 4 thirteen weeks to encourage root and flower bud development / then place containers in a well lit location with temp of 16 for for 4 weeks before flowering commences

Question 53

What is a disease of bulbs, its symptons and control method

Answer 53

Basal rot/bulb rot : pinkish-white fungus between affected scales and on the base plate in stored bulbs / when the bulbs are planted the foliage may yellow prematurely and not flower

Control : no chemical control / plant resistant cultivars / preferable to not store damaged or soft bulbs to avoid the disease

Question 54

State what is meant by each of the following methods of pest and disease control in a protected structure:

cultural / biological

Answer 54

Cultural

prevention or control of pests and diseases through the management of the growing environment / this can involve the following practices e.g. crop rotation / use of resistant cultivars . timing of cultivations and planting / modification of the soil pH / managing the level of humidity in a protected structure

Biological

application of living predators, parasite or pathogens to control pests and diseases / can include the use of the predatory mite Phytoseiulus persimilis to control Red Spider mite or parasitic wasp encarsia formosa to control glasshouse whitefly