Does washing fruits and vegetables reduce the symptoms of Crohn's Disease?Canadian Partnership for Consumer Food Safety Education

Possibly.

In general, it is good practice to wash fruits and vegetables.

Canadian Partnership for Consumer Food Safety Education:

Safe Handling of Fresh Fruits and Vegetables, It's Your Health, Canada Health

"About Foodborne Illness" from FoodborneIllnesses.com Common Bacteria and Viruses that cause Food Poisoning

"Ten everyday foods most likely to make you sick" from The Ottawa Citizen