How many letters does the top answer for “a chemical agent that destroys plants or inhibits their growth” have?

The most common answer is herbicide (9 letters).

Crossword clue: a chemical agent that destroys plants or inhibits their growth

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

herbicide 9 letters wn-def

a chemical agent that destroys plants or inhibits their growth

weedkiller 10 letters wn-def

a chemical agent that destroys plants or inhibits their growth