Environment: SMP
Pack: Nuts and Bolts: Retorqued

// Everything's going to plan. No, really, that was supposed to happen.
Description: Watching Server

java.lang.Error
at net.minecraft.world.World.func_72964_e(World.java:303)
at net.minecraft.world.World.func_175726_f(World.java:298)
at net.minecraft.world.World.func_180495_p(World.java:842)
at squeek.applecore.api.plants.FertilizationEvent$Fertilized.(FertilizationEvent.java:74)
at squeek.applecore.asm.Hooks.fireFertilizedEvent(Hooks.java:323)
at squeek.applecore.asm.Hooks.fireAppleCoreFertilizeEvent(Hooks.java:318)
at forestry.arboriculture.blocks.BlockSapling.func_176474_b(BlockSapling.java)
at hellfirepvp.astralsorcery.common.tile.TileTreeBeacon.searchForTrees(TileTreeBeacon.java:153)
at hellfirepvp.astralsorcery.common.tile.TileTreeBeacon.func_73660_a(TileTreeBeacon.java:87)
at net.minecraft.world.World.func_72939_s(World.java:1804)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:620)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:709)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:387)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
at java.lang.Thread.run(Thread.java:748)

It seems when when combining applecore, forestry and astral sorcery's tree beacon, the server can threadlock when a forestry tree attempts to mutate during the fertilization event.