The leaf stem or mid-rib typically takes longer to fully dry than the leaf lamina. If tobacco is taken down for stripping too early this may result in a condition known as fat stems.  Fat stems can be a problem in air-cured tobacco like burley.

Fat stems can cause high moisture readings and mold when baled. Leaves with fate stems should be left out loose or loosely tied and hung over a tobacco stick to dry before baling.