Q: I have not seen this before. Is this from spiders?
A: You have an enormous infestation of spider mites. The last several weeks of 2019 were perfect for spider mites: hot and dry. Here, their population exploded and the plant is not long for this world.
If you like, you can use a stick to wind the webbing off the plant….. but it will not recover.
Be cautious about planting a marigold in this spot next year, since it is so common to have spider mite problems. Choose another annual flower instead.