Step 1: Scrape off any excess pumpkin pulp or puree from the fabric.
Step 2: Run the fabric, inside out, under the cold water to flush out as much of stain as possible.
Step 3: Pretreat the stain with a laundry stain remover.
Step 4: Launder the clothing in the hottest water the fabric will allow to get out the stain, and either chlorine bleach if the fabric will allow it, or color bleach if not.
Hint: Make sure the stain is gone after washing, but before you place in the dryer or you may set the stain. Repeat if necessary.
source: Stain Removal 101