Plant Diseases and Defences
- Created by: India.02
- Created on: 06-05-19 18:29
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- Plant Diseases and Defences
- Defences
- Physical
- Plant leaves and stems have a axe cuticle - provides a barrier to stop pathogens from entering
- Plant cells are surrounded by cell walls that are made of cellulose - physical barrier to stop pathogens that make it past the waxy cuticle
- Layers of dead cells around their stems - bark on tress - stops pathogens from entering
- Chemical
- Antibacterial chemicals that kill bacteria - witch hazel from the mint plant
- Other plants produce poisons - deter herbivores - tobacco plants, foxgloves, deadly nightshade
- Mechanical
- Thorns and hairs stop animals from touching and eating them
- Other plants have leaves that droop or curl when touched - prevent themselves from being eaten by knocking insects off and moving away from things
- Some plants mimic other organisms - several species of plant in the 'ice plant family' (southern Africa) look like stones and pebbles - tricks other organisms into not eating them
- Physical
- Diseases
- Identified by...
- Looking up the signs in a gardening manual or on a website
- Taking infected plant to a lab - scientists can identify the pathogen
- Testing kits that identify the pathogen using MA
- Pest infestations can be seen on the plants
- Signs and Symptoms
- Stunted growth - spots on leaves - patches of decay - abnormal growths - malformed stems or leaves - discolouration
- Plants can be infected by viral, bacterial and fungal pathogens - can also be infested and damaged by insects and pests - e.g. aphids
- Identified by...
- Mineral Ions from the Soil
- Nitrates are needed to make proteins and for growth - lack of nitrates causes stunted growth
- Magnesium ions needed for making chlorophyll - needed for photo-synthesis - lack of magnesium causes yellow leaves and chlorosis
- Defences
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