If a ball is lost outside a water hazard (including in an accumulation of leaves), the player must proceed under Rule 27-1 incurring the penalty of stroke and distance.
If accumulations of leaves seasonally create an abnormal problem, the Committee may make a temporary Local Rule declaring such accumulations through the green at certain holes to be ground under repair. Please see Decisions 33-8/31 and 13-4/33 in this regard.
In the absence of this Local Rule, the player must proceed under Rule 27-1 under penalty of stroke and distance when his ball is lost, even if it is lost in an accumulation of leaves.