Just wondered if Mekanism is supposed to be able to use Forestry saplings. I was hoping to run extra saplings from tree farms through the crusher and eventually produce plastics. Something I pulled up on google led me to believe Forestry saplings worked at one point in time. I am running Mekanism 8.1.5.246, Forestry 3.6.2.19 and Forge 10.13.4.1448

Fixed!

I am also noticing this as well. I even tried using modtweaker to re-add the recipes. With and without modtweaker, forestry oak saplings show up in crusher recipes, but nothing happens when you place any forestry saplings in. MinefactoryReloaded and IC2:Experimental trees work fine. I have some test info of when it was working and not working in a test enviroment. If you want additional information or tests, let me know.

Test enviroment

Forge Mod Loader version 7.99.30.1492 for Minecraft 1.7.10
Java is version 1.7.0_71 64-Bit, running on Windows 7:amd64:6.1

Supporting Mods

buildcraft-7.0.14
buildcraft-compat-7.0.8
CodeChickenCore-1.7.10-1.0.7.46-universal
CoFHCore-[1.7.10]3.0.3-303
CoFHLib-[1.7.10]1.0.3-175
forestry_1.7.10-3.6.3.20
<Mekanism, MekanismGenerators, and MekanismTools. Various versions>

Testing Method

In creative mode, in a fresh local world, place a creative energy cube. Then place a crusher. Open the crusher GUI (confirming power). Use creative GUI to give yourself a Forestry Oak sapling. Place it in the input slot of the crusher GUI and observe if the crusher begins to operate.

Results

Thoughts

Forestry saplings all share the same id and metadata, and only differ by the HUGE block of NBT data for each of them. Could this be the problem? The Buildcraft autocrafter thinks an unanalyzed sapling is completely different than an analyzed one, despite it being the same id and meta.

Crude workaround

Use the following in a MineTweaker script to allow converting forestry saplings into plain Oak saplings in a crafting grid or autocrafter.
recipes.addShapeless(<minecraft:sapling>,[<Forestry:sapling:0>]);

Possibly related

#2787 #2500