A study by Yang et al, published in the Journal of Agricultural and Food Chemistry, measured the effectiveness of commercial and homemade washing agents in removing surface and internalized pesticide residue from apples.

Surface pesticide residues were most effectively removed by baking soda solution (1 tsp baking soda per 2 cups water).  However, the apples had to be washed for 12-15 minutes to completely remove the pesticide.  Also, this process did not remove the pesticides that had penetrated into the apple itself.  Only peeling can achieve this, but then beneficial bioactive components in the peel are also removed.  See here for an article about this study.

At ACLP, we recommend that you buy organic fruit whenever possible.