Vittorio,
I grow Pumpkins, there are many similarities between the two plants, even common diseases and insect damage, not to mention nutrient requirements.
I've seen similar many times with herbicide damage, at first it appeared that it could be Mosaic virus, but I really believe it to be an herbicide. I'd ask your neighbors what they spray.
Worm tea is great, I'd give them soluble Kelp/seaweed, it can help a plant that is in shock.
We always recommend a product called Sil-guard (Potassium Silicate) Silica hardens the leaf and strengthens the xylem vessels (stem) of plants. It reduces water loss through transpiration, and is particularly beneficial when a plant is under environmental stress. By hardening the cell walls of plant tissue, silica also enhances a plant's resistance to sucking insects and wards off fungal disease.
Anyway, I don't mean for this to become a sales pitch, message me and I can go over a few products that may help, but just be advised if it is herbicide damage, it will be difficult to recover the effected area.
Tom