The answer to 'why is my stone walkway disease' is that a stone walkway can become discolored, cracked, or uneven for several common reasons. This could be due to weathering, improper installation, weed growth, or damage from heavy foot traffic.
Some common symptoms include discoloration, cracking, uneven settling, and weed/moss growth between stones. The best solution depends on the extent of the damage, but often involves cleaning, resetting, or replacing the stones. For severe issues, it's best to call a professional landscaper to assess and repair the walkway properly.