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.
The symptoms of rose black spot and the tobacco mosaic virus (TMV) are shown below.
Symptom and example of disease
To control the spread of TMV, farmers must:
Black spot is treatable using fungicides. The fungicide can also be sprayed on rose bushes to prevent infection, especially when the weather is likely to be warm and wet.
Transmission can be reduced by:
Many rose growers also now grow resistant varieties of roses.