Disease in plant crops is like a war being waged by microorganisms and insects. The main invaders of plant species are bacteria, fungi, insects, and viruses.
In the following pictures, diseases of fruit, vegetables and sunflower were caused by different fungi.
Insects that are very tiny can still inflict major damage on the plants that we grow for food.
Viruses can cause many different phenotypes in the plants that they infect.
There are several groups of plant parasitic nematodes that cause reduced harvest or crop losses. Some of these result in damage that is easily visible, such as the formation of characteristic galls on the roots of the infected plants.
It is not always easy to decide what organisms are causing the disease symptoms that we see on our fruits, vegetables, crops and ornamental plants. Scientists have developed many tools for identifying which organisms are causing disease.
The above photos show a number of tools plant pathologists use to understand what is causing disease and how the plant reacts.
Once a disease has been identified, it is possible to begin to find ways to stop the spread of the disease and to develop plants that are not susceptible to the microorganism and so can stay healthy.
Go to Activity 2 (Gel electrophoresis - What is it? How does it work?)
Go to Activity 3 (Restriction enzyme digestion - How does it work? Why is it useful?)