I came across this list a few years ago and found it helpful. What I learned was that even if there aren't any pesticides on the surface when you purchase or wash the produce you're about to eat, the plants were sprayed with pesticides during their growth and was absorbed through their leaves and the roots absorbed pesticides in the ground water. So, it's part of the fruit and isn't something that can be washed away.
Sometimes we can't always buy everything organic, I know. But, it's nice to know the top 13 types of conventional produce to avoid and to buy as organic if we can.
3. Sweet Bell Peppers
10. Imported grapes