The Environmental Work Group has put together a list of the pesticides found on and in fruits and vegetables.  They call the twelve worst the dirty dozen, although the list contains about 50 items from worst to least.

The twelve worst right now from worst to least are: Peach, Apple, Sweet Bell Pepper, Celery, Nectarine, Strawberries, Cherries, Kale, Lettuce, Imprtted Grapes, Carrots, Pears.

Dirty Dozen Pocket List

See the entire list here at Environmental Work Group