The various methods which are used to control plant diseases are:
1. Crop rotation :
It is a very good method to control plant diseases. It is because parasites are very choosy about their hosts, therefore in the absence of the latter they disappear. Since rotation of crops involves the change of crops every year, it helps in controlling the diseases on account of change of in the host.
2. To develop newer disease resistant varieties :
The newer disease resistant varieties are being produced. It is very important method used for control of plant diseases.
3. By spraying fungicides :
Two common diseases of wheat crop are smut and rust. Both of these diseases are caused by fungi. In the former disease black powdery mass is deposited in wheat grains whereas in the latter the straws of wheat plants develop brown spots, by spreading fungicides these diseases can be controlled.
4. Disease of potato and cotton crop :
The potato crop comes in the grip of blight, a fungal disease. So it can be controlled by spraying fungicides like copper oxychloride, sulphur etc
The cotton crop so often suffers with a disease called bollworm. Obviously the disease is caused by worms. Therefore it can be controlled by spraying, malathion, BHC,DDT, etc.
5. Diseases of rice crop :
The two diseases of rice crop, which are very common, are blast and root rot. In addition to this, small insect pests also attack paddy crop. These insect pests are stem borer and gundhi. These diseases can be controlled by spraying suitable pesticides on the crop.
6. By sowing ordinary varieties of crop :
Actually high-yield varieties of crops are more susceptible to diseases than ordinary varieties. Therefore, by sowing the latter variety of crop. One can get rid of the plant diseases.