Weed control, definition

With the first invasion of resistant weed populations, prompt action has been essential to avoid serious and permanent problems. Preventive action to avoid herbicide resistant weeds from evolving in the first place is definitely the best strategy. It is virtually essential in all cases of herbicide resistance to have other classes or types of herbicides, with alternate sites, modes of action and degradation available. In some countries, because of failure to respond promptly, the lack of suitable alternatives, or for other reasons, triazine resistant weeds have not been controlled, resulting in rapid spread,.leading to the almost total loss of effective weed control with these herbicides (1). 

Pyrithiobac-sodium is a pre- and post-emergence herbicide to control broad-leaved weed and grasses The residue definition is for the parent, pyrithiobac-sodium, only. 

Stable to acid and base in the pH range 3-8. Thenylchlor is a chloroacetamide herbicide for the preemergence and post-planting control of annual grass and broad-leaved weeds in paddy rice The residue definition is for the parent, thenylchlor, only... 

This comprehensive definition makes it elear that a wide number of substances may be eonsidered to be pestieides, and that the eommonality among all pestieides is their ability to provide eontrol over pests. A variety of classifications for pesticides have been developed that are specific for the type of pest controlled. Insecticides, for example, are pesticides that control insects, while herbicides control weeds and fungicides control plant diseases (molds). In addition to these major classifications of pesticides, there are many other classifications. These include nematicides (for nematode control), acaracides (mite control), rodenticides (rodent control), molluscicide (snail and slug control), algacides (algal control), bacteriocides (bacterial control), and defoliants (leaf control). 

A computer survey of the patent literature made a year ago came up with 515 recent patents claiming herbicidal synergies. A perusal of the abstracts of 45 of them, chosen as a sample, showed that the patent community uses a broader definition of synergy than used here they believe that there is a synergism when two herbicides control more weed species than each separately. This would better be termed "complementarity. The overlap of control range allows a lowering of herbicidal rates, which may or may not be due to a metabolic... 

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