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FUNGICIDES
&
PESTICIDES (major classifications of pesticides…
FUNGICIDES
&
PESTICIDES
What are PESTICIDES
any substances or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, any substances or mixture of substances intended for use as a plant regulator, defoliant, or desiccant and any stabilizer.
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INSECTICIDES TOXICITY
Chlorinated hydrocarbon family is the first major synthetic group of insecticides. This includes DDT, aldrin, dieldrin, methoxychlor, and chlordane.
noted for high environment persistence, that result in long term but also contributed to the environment build up, and biological magnification, leading to significant ecological and environmental impacts.
typically result from a variety of mechanism, such as nerve damage, muscle poisoning, sterilization, and desiccation
HERBICIDES TOXICITY
Herbicides exert their toxic action on weeds through a number of different mechanism.
- Preplant herbicides –apply before a crop is planted.
- Preemergent herbicides –apply after planting but prior to the development of weeds
- Postemergent herbicides –used after weeds appear.
Some herbicides (eg; glyphosate) exert broad- spectrum weed killing effects making them toxic to virtually all forms of plant material include crop.
FUNGICIDES TOXICITY
Many different fungicides exist, including sulfur, aryl- and alkyl-mercurial compounds, bis-dithiocarbamates and chlorinated phenols.
Molds and other plant diseases are controlled by fungicides, which act to affect the growth or metabolism of fungal pests.
RESIDUES IN FOOD
After the pesticides are used to treat cultures, they are deposited on them and, in order to be marked, they must be lower than the legal limit at harvest.
The amount of pesticides residues present on fruit and vegetables at harvest depends on the initial deposit and on the residues reduction rate.
- Initial deposit
A number of factors determines the level of the initial deposit, some depend on the pesticides (rate, formulation, application methods), others on the culture (surface, weight ratio, shape).
- Disappearance rate
Pesticides are mostly lipophilic and exert their activity by contact or systemically, depending on whether they penetrate the plant or not.
Disappearance of the residues will depend on the combined effect of these factors.
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