trunks, branches and stems can split due to increased osmotic pressure along with rapid growth
-'growing pains'.
Increase osmotic pressure is the key here as Ziggy is saying. Like a hot dog splitting. For this to happen I would think would require suppression of the stomata and lots of water coming into the plant. This means you would have to have a hypotonic solution outside the plant. Hypotonic meaning there is more solute inside the plant than outside. So water desires to rush in to even out the dissolved solute concentrations inside and outside the plant. Too much pressure and we would see that split. Especially if the guttation mechanism isn't allowing that excess sap to go out the "safety vents"and if the stomata are closed off.