Identification can be made by:

1. Reference to a gardening manual
2. Taking infected plants to a laboratory to identify the pathogen
3. Using testing kits that contain monoclonal antibodies.

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Symptoms of plant disease:

Stunted growth Spots on leaves Growths Malformed stems or leaves Discolouration Presence of pests.

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Nitrate deficiency → Less protein synthesis → Stunted growth

Magnesium deficiency → chlorosis (no chlorophyll) → leaves turn yellow + less photosynthesis → Stunted growth

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Physical defences:

• Cellulose cell walls
• Tough waxy cuticle on leaves
• Layers of dead cells around stems (bark on trees) which fall off </aside>

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Chemical defences:

• Antibacterial chemicals
• Poisons to deter herbivores </aside>

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Mechanical defences:

• Thorns and hairs deter animals
• Leaves which droop or curl when touched
• Mimicry to trick animals </aside>