When does decay stop in materials?

Decay in materials, particularly wood, ceases when the environmental conditions become unfavorable for the growth of decay-causing fungi. Fungi require specific temperature and moisture levels to thrive; thus, when these conditions are not met—meaning the wood is either too dry or too cold—fungal activity is inhibited, and decay does not progress. This understanding is crucial in wood preservation practices, as controlling the moisture content and temperature is a key strategy in preventing decay.

While the treatment of wood with preservatives can significantly delay or reduce the likelihood of decay, it does not necessarily stop ongoing decay if the conditions remain conducive for organisms. The moisture and temperature concept emphasizes the fundamental environmental requirements of fungi, providing a more direct insight into the mechanisms that promote decay.

The other choices, such as treating wood, the state of the wood being green, or exposure to sunlight, do not address the core requirement for fungal growth, which hinges on moisture and temperature. Thus, understanding that decay halts when these unfavorable conditions arise highlights the importance of managing environmental factors in wood preservation.