Best to buy organic (because even after washing, these foods still carry higher levels of pesticide residue than others): apples, cherries, grapes, peaches, nectarines, pears, raspberries, strawberries, bell peppers, celery, potatoes, and spinach.
No need to go organic on these foods (because these products generally don’t contain pesticide residue on them): bananas, kiwi, mango, papaya, pineapples, avocado, asparagus, broccoli, cauliflower, corn, onions, and peas