Rot in Mahogany - part 2

[Old Bear]

How do the rot spores travel? My concern is the plank adjacent to the rot. Seems hard and sound. Will rot cross the joint?

[Dan McCosh]

I'm no expert, but I think the thing to remember is that all wood has rot fungi in it. It is activated when the tree dies, and the conditions allow it to grow. It's natures own recycling program. The idea is to keep the wood from reaching the moisture content, temperature, etc., where rot propogates.
Rot mainly seems to extend along the fibers in the wood, rather than attacking a surface parallel to the grain. A seam often has problems on both sides, as the conditions are more or less the same on both sides of the seam. That isn't exactly the same as the rot actively moving across the seam, however. Theoretically, the seam compound would act as a barrier.

[NormMessinger]

What Dan said: The mycelia of fungus travels primarily along the grain of the wood and can extend well beyond the punky wood. Spores are air or water born.