Some terminologies
PROTECTION: Use of chemicals for the control of plant diseases is generally
referred to as protection or therapy.
Protection: The prevention of the pathogen from entering the host or checking the further development in already infected plants by the application of chemicals is called protection and the chemicals used are called protectants.
Therapy means cure of a disease, in which fungicide is applied after the pathogen is in contact with the host. Chemicals used are called therapeutants.
Fungicide: Any agent (chemical) that kills the fungus.
Fungistat: Some chemicals which do not kill fungi, but simply inhibit the fungus growth temporarily.
Antisporulant: The chemical which inhibits spore production without affecting vegetative growth of the fungus.
Fungicides are classified into three categories:
- Protectants:
- These are the chemicals which are effective only when used before infection (prophylactic in behavior).
- Contact fungicides which kill the pathogen present on the host surface when it comes in contact with the host are called protectants.
- These are non-systemic in action (i.e, they cannot penetrate plant tissues).
- Ex: Zineb,sulphur, captan, Thiram, etc.
- Eradicants:
- Those chemicals which eradicate the dormant or active pathogen from the host.
- Ex: Lime sulphur, Dodine.
- Therapeutants:
- These are the agents that inhibit the development of a disease syndrome in a plant when applied after infection by a pathogen.
- Therapy can be by physical means (solar and hot water treatment) and chemical means (by use of systemic fungicides, i.e., chemotherapy).