Plain ole tarps do disintegrate quickly. "Silver" could just be a different color of plain ole tarp, in which case don't expect much better from it.
OTOH, the serious agricultural tarp material that feed stores etc sell for farmers to cover hay stored outdoors, and *some* of the silver plastic sold to cover hoophouse greenhouse structures, can last several years or more. It is however a lot more expensive than the lil' blue jobbies.
Pat