Chemicals used in the control of fungi are called fungicides. Chemical measures are introduced to aid in the eradication of diseases, protecting the crop against diseases and curing the crop of an existing disease.
Eradication of plant diseases involves the control of the target pathogen while the pathogen is still on the outside of the crop plant. This is being done through seed treatments and soil fumigation before planting.
Protective measures are measures taken to place a chemical barrier to the outside of the plant or a systemic compound within the plant. The chemical is applied before the pathogen is present in the plant.
Curative measures are steps taken once the pathogen has already penetrated the crop. For this type of control, the chemical must be taken up by the plant, and must therefore have either a trans-laminar action or a systemic action.
Eradicating or curative fungicides kill the disease on or inside the plant once the disease has developed. Protective fungicides form a protective layer around the seed or crop, killing fungal spores during their germination.
Fungicides are divided into three major groupings:
Click here to view a video that explains disease fungicides.