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Scientists want to identify potential plant pathogens as quickly as possible to reduce the likelihood of an infection spreading. The process to identify a disease may include the following steps:

1. Following a report of a possible infection, scientists will visit the location.
2. To avoid any confusion it is essential they look at other factors that might cause similar symptoms. For example, damage to leaves might be caused by a pathogen or grazing animals.
3. The scientists will try to identify any environmental causes such as pollution that might be affecting the plants.
4. Finally they will photograph the symptoms and take samples for laboratory analysis.

Once an infection has been identified, scientists will look for any patterns in the distribution of infected plants. Do they all appear downwind of the first infection? Are future cases reported along the banks of rivers and streams?

Symptoms of plant disease

Plant pathogens cause diseases with a range of different symptoms. These symptoms can be used to identify the pathogen and then treat the disease, or limit its effects.

Pests can also cause damage to plants. Examples are the insects, aphids and mealybugs. Although these do not cause disease, as pathogens do, they can weaken and damage the plant. It is important to identify which pests are causing symptoms, as well as identifying which pathogen is causing a disease, so that the correct treatment can be decided.

The symptoms of common plant infections are show below.

Identification

Farmers and gardeners often use books like gardening manuals and the internet to identify plant diseases. They do this by comparing the symptoms of their plants with images of other infected ones. Gardeners can also take a small cutting of an infected plant (or a photograph of it) to a local garden centre. Here staff can help identify the disease by looking at its symptoms. Gardeners can then buy suitable treatments from the garden centre to treat the disease.