Who chariotest to their dark wintry bed

What is the grammar of the word chariotest?
The verb chariot -- when in the form for second person "thou" - turns into chariotest?

Context:

Ode to the West Wind
1、
O wild West Wind, thou breath of Autumn's being
Thou, from whose unseen presence the leaves dead
Are driven, like ghosts from an enchanter fleeing,
Yellow, and black, and pale, and hectic red,
Pestilence-stricken multitudes:O thou
Who chariotest to their dark wintry bed
The winged seeds, where they lie cold and low,
Each like a corpse within its grave, until
Thine azure sister of the Spring shall blow
Her clarion o'er the dreaming earth, and fill
(Driving sweet buds like flocks to feed in air)
With living hues and odors plain and hill:
Wild Spirit, which art moving everywhere;
Destroyer and preserver; hear, oh, hear!