[header] How to keep squirrels from eating pumpkins [title] Spray with commercial squirrel repellent. [step] Apply a thorough coat of repellent to all sides of the pumpkin according to label instructions. [substeps] You may need to reapply the repellent every few days, especially after the rain. 
Many repellents are non-toxic since they are formulated to drive squirrels away rather than kill them. Most deer repellents will also be effective since squirrels and deers are driven off by many of the same scents.