This list of fruits and veggies has the highest pesticide residues.
Apples #1!!!!

Dirty Dozen 2011
  1. Apples
  2. Celery
  3. Strawberries
  4. Peaches
  5. Spinach
  6. Nectarines (imported)
  7. Grapes (imported)
  8. Sweet bell peppers
  9. Potatoes
  10. Blueberries (domestic)
  11. Lettuce
  12. Kale/collard greens


Now some positive, but these are also included in the report. Just not as "dirty".

Clean Fifteen 2011
  1. Onions
  2. Sweet corn
  3. Pineapples
  4. Avocado
  5. Asparagus
  6. Sweet peas
  7. Mangoes
  8. Eggplants
  9. Cantaloupe (domestic)
  10. Kiwi
  11. Cabbage
  12. Watermelon
  13. Sweet potatoes
  14. Grapefruit
  15. Mushrooms


Source