Spotting and identifying plant disease, nitrate and magnesium deficiency, and the physical, chemical and mechanical defences of plants.
What you will learn
- Recognise signs of plant disease and how to identify the cause
- Explain the effects of nitrate and magnesium deficiency
- Sort plant defences into physical, chemical and mechanical
- Calculate percentages from plant disease surveys
Spotting disease
Signs: stunted growth, spots on leaves, areas of decay, growths, malformed stems or leaves, discolouration, and pests such as aphids, which can carry viruses.
To find the cause: check a gardening manual or website, send samples to a laboratory, or use a testing kit containing monoclonal antibodies.
Not every problem is a pathogen. A plant short of nitrate ions cannot make proteins, so its growth is stunted. Short of magnesium ions it cannot make enough chlorophyll (the green pigment that absorbs light for photosynthesis), so the leaves yellow (chlorosis).
The rest of this lesson and its 10 practice questions are locked.
In this lesson
- Spotting disease
- How plants defend themselves
- Try it: Signs of disease
10 practice questions, marked as you go; about 20 minutes in all.
Key terms
Nitrate, Magnesium, Chlorosis
In this unit: Infection and response
Pathogens and how they spread, the body's defences and the immune system, vaccines, antibiotics and resistance, drug trials, and (Biology only) monoclonal antibodies and plant disease.