Postemergence herbicides typically have been most effective on what type of weed? css 202

Post emergence herbicides has been most effective on Emerged weed I.e weed that is spring up from the soil.

Explanation:

Weeds are unwanted plant or vegetation that grow on the field.

Herbicides are toxic substances that are used to kill or control unwanted vegetation, hence they are called weed killers.

Herbicides are classified into pre-emergence and post emergence herbicides.

Pre-emergence herbicides are herbicides use to control weed before they emerged.

Post emergence herbicides are herbicides use to control emerged weeds.

Post emergence herbicide is classified into contact and systemic post emergence herbicides.

Contact post emergence herbicids only control the plant parts they come in contact with while systemic post emergence herbicides are translocated to all over the plant parts.

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answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.