It's coming from the decking which is rotting but the landlord isn't interested in replacing it. I've got mares tails coming up under it and moss growing. It smells like something has died under there. Any ideas what I can do? I no longer have a jet washer to clean it but will buy one if necessary. My back is not up to scrubbing it with a decking brush. there was a dead rat on the decking a few weeks ago which was promptly disposed off outside the property. I wonder if there's more under there 😩 next door has poison down.