Yes, FORESTERS is a Scrabble word!

Letter values in Scrabble US: F 4, O 1, R 1, E 1, S 1, T 1, E 1, R 1, S 1.

Is it a valid word?

FORESTERS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

English writer of adventure novels featuring Captain Horatio Hornblower (1899-1966)
someone trained in forestry

Also: c. s. forester, cecil scott forester, tree farmer.

Not playable in Scrabble US: ARBORICULTURIST.