Pesticide germicide refers to a class of pesticides that can kill or inhibit fungus, bacteria and other kinds of pathogens that are harmful to plants. Such kind of pesticides have toxic, killing or inhibitory effect on pathogenic fungus and bacteria that are harmful to plant growth and development or alternatively have suppression effect on the development of spore and mycelium. However, it usually doesn’t affect the normal growth of plant. Bactericide can be used to control and prevent plant diseases.
The earliest discovered pesticide germicides that used for the prevention and control of plant diseases are mainly chemical element, natural substances and inorganic compounds. It is as early as 1000 BC when people had already discovered the disease prevention effect of sulfur. In 470 BC, someone have sprayed olive extract for prevention and treatment of disease and applied the mixture of alcohol and cypress leaf for dipping wheat seeds for prevention and treatment of diseases. In 1705, Mercuric chloride had been first used as a kind of wood preservative and then used for the prevention and treatment of common blunt of wheat. The wide application of sulfur in the prevention and control of plant disease started at 1824 when people found that sulfur had special efficacy in the treatment of peach powdery mildew. In 1880, the United States had successfully applied lime sulfur mixture for controlling the grape powdery mildew and had started the history of application of lime sulfur mixture for the prevention and control of plant diseases since then. In 1971, people had for the first time used copper sulfate for processing the wheat seeds for prevention and control of the seed-borne disease. In 1882, the French scientists P.M. A Millardet) had found that bordeaux mixture had excellent control effect on the grape downy mildew, establishing the status of the bordeaux mixture in the germicide. Bordeaux mixture still has application in current time.
From the end of the 18th century to the 1850 s, in order to seek the substitutes of copper and mercury, people had strengthened the study of organic germicides. Those studies of the biggest impact is the germicide effect of dithiocarbamate derivatives reported by W. H. Tisdale et al. This discovery had opened up a new era of using organic compounds as pesticides germicide. After the finding of the germicide effect of ziram, ferbam and TMTD, in 1935, Dupont had first discovered the germicidal effect of sodium dithane in the dithane class. People had put it into production in 1943. After 1960s, dithiocarbamate salts fungicide had gradually developed into a class of germicide of the largest output worldwide.
Since the founding of people’s republic of china to the early 1970s, the germicide during this period fungicide was still mainly mercury preparations. At the end of 1970s, people had stopped using mercury preparations and instead has started to apply mildothane and carbendazim as pesticide for the prevention of disease of a variety of crops. During this period, the usage amount of the pesticide is generally low with the pesticides dosage being 20 ~ 100 ml per acre, germicide being 30 ~ 100 grams per acre while the overall annual dose in the city being about 1 500 ~ 500 tons every year.