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This publication is based on the plant processes and reaction sites
for which reliable knowledge on both their physiology and
biochem-istry and the mode of herbicidal action is available.
Targets of the agrochemical research, such as enzymes of
biosynthetic pathways or herbicide-binding peptides in the
photosynthetic membrane, are highlighted. Detailed knowledge about
the target sites will allow bio-chemical model systems to evaluate
the biological activity of newly synthesized compounds before their
conventional screening in the greenhouse. Quantitative
structure/activity relationships should be performed more reliably
with simple biological species or enzymol-ogy assays, to aid in the
rational design of pesticides. This text is highly valuable for
plant physiologists, pathologists, and chemists in the agrochemical
industry and universities.
Since the middle of the Sixties, new types of formulation for
biologically active com pounds have been developed, which have been
introduced into the literature under the term Controlled Release
Formulations (CRF). Stimulated by results from former and
successful pharmaceutical research, which was engaged in the
production of prepa rations with protracted effects (introduction
onto the market in the year 1952 of D amphetamine in the form of
pellets, coated to varying degrees with fats and waxes) 1),
experiments were carried out to transfer the prolongation of
effectiveness to pesticidal substances also, by means of a depot
formulation. Initial work was concerned with the production of
protective coatings for sonar systems in marine ecosystems. By
means of antifouling paints or rubber coatings containing
tri-n-butyl-tin oxide (TBTO), the growth of marine organisms on
sonar domes, buoys and hulls in the water could be effectively
prevented 2. 3). Controlled release formUlations of pesticides are
defined as depot systems which continuously release their toxic
constituents into the environment over a specified period of time
(usually months to years) 4). According to this definition, such
formu lations can be successfully employed where a chronic exposure
to biologically active compounds is required over a longer period.
The following hypothetical example is intended to illustrate this
5). In Fig. 1, the duration of activity of a non-persistent
pesticide with a loss rate under environmental conditions of t1/2 =
15 days, is graphically illustrated."
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