ABSTRACT
Fungicides belong to a group of chemicals called pesticides, which are used to protect plants from pests. The term, fungicide, is applied to all chemical plant protectants that manage fungal diseases. The systemic fungicides differ from contact fungicides in that while they also provide an external barrier to infection, they are in addition absorbed by the plant, and translocated throughout. Systemic fungicides have controlled diseases, such as necrotic ring spot, summer patch, and stripe smut that once were considered uncontrollable. Resistance occurs when a fungus which was sensitive to a fungicide becomes resistant to it. Prior to fungicide selection pressure, the original wild type sensitive strain predominated, and resistant strains which arise by mutation occurred in small numbers. Fungicides are among the safest pesticides, but they are nonetheless pesticides and should be treated accordingly. Fungicide sprays are applied when they are infecting the plant, which contributes further to the elimination of sensitive wild type individuals from the population.
