3.Plant Disorders Flashcards
1
Q
What is meant by the term plant disorder?
A
- A harmful disturbance of normal plant functions brought about by a ‘non-living’ factor - abiotic
- The environment in which the plant is being grown e.g Frost, water logging, PH Level
2
Q
How are plants affected by frost, in both hardy or non-hardy plants
A
Non-hardy plants
- Ice crystals form inside plant and freeze
- Contents expand, cells rupture and are killed
- Plants blacken and die
- Buds discolour and wither
Hardy plants
- Scorched and damaged leaves
- Distorted buds
- Damage to young shoots and tips
- Reduced production of flowers and fruit
- If repeated often can cause plant death
3
Q
State methods of avoiding frost damage and treatment
A
- Provide protection such as straw, fleece,cloches etc or bring tender plants under cover
- Mulch with organic material
- Avoid planting in a frost pocket (hollow/low lying land)
- Plant tender plants out after the risk of frost has passed/harden off before hand
- Choose hardier plants (use RHS plant hardiness ratings)
- Spray fruits buds with water after a frost as this can help prevent damage
- Planting of shelterbelts can reduce damage from wind frosts
- Prune back damaged areas
- Apply fertiliser to encourage re-growth
4
Q
Describe how plants are adversely affected by shade.
A
Plants not well adapted to shady conditions:
- Etiolation = pale, spindly growth, lacking in chlorophyll (yellow)
- Long and spindly because they develop long internodes
- Leaves fail to expand
5
Q
How to avoid problems associated with shade
A
- Choose suitable plants for the correct location
- Supplementary light may be used in protected environments
- Consider aspect/location when planting
6
Q
Describe how plant growth is adversely affected by drought
A
- Shinny leaves change to dull
- Often causes premature leaf drop
- Less plant turgidity, unable to properly photosynthesise
- Older leaves turn brown and fall off
- If permanent wilting point is reached then the plant will die
7
Q
Describe how to avoid problems from drought
A
- Plant selection essential in areas prone to drought, e.g Silver/Green grey leafs reflect light helping keep water in
- Soil structure/water-holding capacity can be improved by addition of organic matter and cultivation
- Shade and wind protection can be provided
- Regular watering using irrigation systems or by hand
- Mulching to help avoid evaporation
- Consider planting a gravel garden
8
Q
Describe how plant growth is adversely affected by water-logging.
A
Occurs when all pores are full of water = no air in soil
- Leaves yellowing, wilting, defoliation
- Leads to anaerobic respiration - build up of toxic ethanol
- Stunted growth
- Moss on lawns
- Black rotten roots
- More damaging in warm seasons - as they respire more
9
Q
State one method of lessening the affect of water-logging on plants.
A
- Cultivation = Improve the structure/drainage of the soil
- Install drainage systems where there is a high water table
- Dig ditch or seasonal pond on low lying land to allow natural drainage
- Choose plants that can withstand wet conditions
10
Q
Describe how plant growth is adversely affected by high temperature damage.
A
- Scorched areas of leaves, typically on the sunny side of plants
- Reduced growth
- Wilting
- Blistering, longitudinal cracking and death of tissues – all entry point for potential plant diseases
- Woodland plants are particularly vulnerable
11
Q
How to avoid damage from high/low temperatures?
A
High temp:
- Plant selection essential in areas prone to high temperatures
- Shade can be provided to help reduce temperatures
- Avoid watering in bright sunlight (droplets focus light)
- Improve ventilation
Low temp:
- Plant selection is essential
- Plants can be protected from cold weather by wrapping horticultural fleece
- Plant in a sheltered spot
- A cold and windy site will often require windbreaks such as hedging
12
Q
Describe how plant growth is adversely affected by soil pH.
A
- Most plants take up nutrients between 6-7pH
- Roots unable to absorb a balance of nutrients - In soils with high pH (chalky or alkaline soils) iron tends to be locked up
- Leaves turn yellow or brown in margins and between veins
- Poor-quality/quality fruit
- Lime induced chlorosis
13
Q
Describe how plant growth is adversely affected by fasciation.
A
- 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
- Apical meristem becomes flattened and elongated and has appearance of many shoots together
- Can be caused by viral infections spread by aphids or mechanical means. Not necessarily fatal
- Fasciation is unpredictable and is usually limited to a single stem. It seldom recurs the following year
- Fox glove often affected
14
Q
State a method of avoiding or dealing with fasciation
A
- Cut out/prune the damaged part of plant
- Fasciation seldom recurs on herbaceous plants the following year
15
Q
Describe how plant growth is adversely affected by rose balling.
A
- Outer petals of rose bud die and become stiff so inner petals cannot emerge
- Buds go brown and drop off or can become covered in grey mold
- Cool, wet weather saturates the outer petals and then the sunshine dries and fuses them into a tight, preventing the bud from opening
- Thin-petalled, double flowers such as rose, peony and camellia cultivars are most susceptible to this condition
