What is a major concern when untreated wood contacts soil?

When untreated wood comes into contact with soil, a significant concern is its susceptibility to rot and pest infestations. Wood that is in direct contact with the ground is exposed to moisture from the soil, which can create an ideal environment for fungi that cause decay. This moist condition can lead to wood rot, diminishing the structural integrity and longevity of the wood.

Additionally, being in contact with soil increases the risk of pest infestations, such as termites and other wood-destroying organisms. These pests can find an easy entry point and source of food in untreated wood, leading to significant damage over time. Thus, the risks associated with rot and pest infestations are paramount when untreated wood is in direct contact with soil.

While other concerns like color change, drying out, and potential cracking are valid in different contexts, the critical issues of rot and pest damage emphasize the importance of using treated wood in applications where it will contact the ground.