The main weakness of the Spore is the cold. WIP.
Cold Biomes
If the internal temperature value of the biome a Spore Mob is currently in is 0.2 or lower, Spore Mobs will continually be given the Frostbite Effect. Furthermore, Spore Mobs can't spawn in biomes that are too cold, though that doesn't include the caves beneath the biome.
List of biomes that affect Spore Mobs:
Any modded biomes with a low enough temperature value.
Base Minecraft Freezing
When under the freezing effect (present in the base game), Spore Mobs will visibly shiver. When taking freeze damage, Spore Mobs will receive 5 damage (2.5 hearts) instead of 1. Snowballs will also inflict freezing on Spore Mobs. Additionally, if a Mob is freezing upon death, they are unable to spawn a Scent. Some specific Mobs will have unique ailments when freezing.
Gallery
An Infected Human shivering in a cold biome.