Fungicides discovery

Wedge, D. E., Kuhajek, J. M. A microbioassay for fungicide discovery. SAAS Bull Biochem Biotech 1998 11 1-7. 

During the evolutionary process of lead-structure optimization, probably well over 50 000 strobilurin analogues were synthesized by competing industrial fungicide discovery research groups worldwide. Several compound types, and even specific compounds, were made independently at almost the same time. 

A final class of uncouplers are compounds that transport protons across the membrane, leading to dissipation of the transmembrane proton gradient, and hence removing the proton-motive force that drives ATP synthase [25-27]. These are the only uncouplers of real significance so far as fungicide discovery is concerned. 

Discovery. The traditional approach to new pesticide discovery was to make iatuitive changes ia the substitueats oa a promising primary chemical stmcture. Initially, materials from any source were subjected to screening for biological activity as iasecticides, herbicides, or fungicides. 

Foliar Fungicides and Bactericides. Of the - 70,000 t/yr as copper in compounds used in agriculture, almost 75% is used in the control of fungi (see Fungicides, agricultural). The first reference to the use of copper as a fungicide dates to 1761 (83) where copper sulfate was used on wheat seed for the control of bunt. In 1807 (84) the discovery of copper as a fungicide was made and the discovery of Bourdeaux mixture (copper sulfate plus lime) followed in 1882. 

The copper compounds include Bordeaux mixture and the so-called fixed coppers including the copper oxides, copper oxychloride, copper oxychloride sulfate, and related materials. Bordeaux mixture, since its discovery about 70 years ago, has been the classic fungicide for the control of late blight and still is more widely used than any other single material. Certain of its qualities, particularly adhesiveness, remain unequaled by its commercial competitors, and it is cheap and effective. However, the inconvenience of preparing Bordeaux mixture, and the unreliable quality of hydrated lime available in most places, have tempted many growers to switch to other copper compounds or organics. 

The biological properties of oxetanes are slowly attracting attention, although many have been known for a long time. For example, 2,2-bis(p-ethoxyphenyl)-3,3-dimethyloxetane is an excellent insecticide, 25 times as potent as DDT (71MI51300). Many oxetanes have been patented as fungicides. The recent discovery of thromboxane A2 and the antileukemic toxanes will undoubtedly stimulate further study of oxetane derivatives for possible medical and biological applications. 

The use of sulfur and copper fungicides dominated the market until 1915 when organomercury seed treatments, derived from discoveries in the pharmaceutical and dyestuffs industries, were shown to be highly effective against cereal diseases. They remained popular until banned in the late 1970s on the grounds of adverse toxicology. 

The first phosphatidylcholine inhibitors were amongst the earliest modern commercial fungicides to be discovered. At the time of discovery, the mode of action was unknown. 

This book examines the chemistry and mode of action of herbicides, insecticides, fungicides and plant growth regulators. It follows crop protection strategies from early discoveries to the present day, emphasising the biochemical targets of the compounds discussed. 

Regardless of the pathways of induced resistance, the end result is identical - a plant with stimulated resistance to plant pathogens. Effective use of induced resistance promoters in I PM systems will likely dramatically reduce the use of conventional chemical fungicides and bactericides in commercial agriculture. It is likely that there are many nontoxic natural substances and microbial species awaiting discovery as induced resistance promoters. 

Derivatives of 2,3-dihydro-l,4-oxathiin and 1,4-benzoxathiins have been patented as agrochemicals. An important development in fungicidal research has been the discovery of so-called systemic fungicides. Unlike surface fungicides which may require repeated... 

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