12 Fruit and Veg the most contaminated by pesticides according to the american non-profit Environment Watch Group.
1. Apples 7. Sweet Bell Peppers
2. Strawberries 8. Nectarine
3. Grapes 9. Cucumber
4. Celery 10. Potatoes
5. Peach 11. Cherry Tomatoes
6. Spinach 12. Hot Peppers
Veggies that do not necessarily need to be organic are those that have a peel or think skin you remove such as onions, avocado, mango, aubergine and winter squash.
Brocolli and asparagus do not attract many pests so are sprayed less (apparently)