Q.Large Philodendron with long with long stems. What is causing the stem to bend and then drop off the stem is very watery n someti
mes burst Tree like Philodendron- Why are the long stems splitting in the middle and very soft to touch with watery feel to the stems that fall off over night?
This could be a fungal or bacterial disease, or it could be a symptom of overwatering. Make sure your plant's soil is allowed to dry out to one inche beneath the surface between waterings as described in the following article, and make sure the pot has well-drained soil and enough drainage holes at the bottom.
https://www.gardeningknowhow.com/houseplants/philodendron/caring-for-philodendrons.htm
Also, check this article for signs of disease on your plant:
http://extension.psu.edu/pests/plant-diseases/all-fact-sheets/philodendron-diseases