There are several situations wherein the application of chemicals becomes necessary. If a susceptible cultivar has to be grown in environments conducive for disease development, protection of such crops with chemicals becomes unavoidable. During the period of rapid development of epidemics, large-scale application of chemicals has to be resorted to restrict further spread of the diseases. Growing glasshouse crops successfully requires intensive application of chemicals. Seed crops and seed stocks have to be protected by repeated application of chemicals to keep the infection below tolerance levels prescribed for different diseases. Fungicides have been found essential for maximizing
yields of crops including staple food crops such as cereals, rice and maize (Anderson, 1995). Substantial benefits on food quality may be derived by application of fungicides for the control of fungi-producing mycotoxins such as anatoxins, ergot toxins, Fusarium toxins; patulins and tenuazonic acid (Pohland, 1993; Schneider and Dickert, 1994).