I noticed that there is some slime at the base of the tree and its green, I don't know what do do about this or if this is normal or not.
It happens and only for that reason it is normal. Myself I don't leave Moss of any type on the soil surface and am very meticulous keeping it off plants. I spent a few hours a few weeks back with another member removing a LOT from a good size Juniper that needed other care and is now aglow with nice growth.
Nitrogen will kill it but leave a "mat" that is no good either. I take a root rake to the soil surface and gently remove all and any growth for starters. I then crush the end of a wooden bamboo skewer and use it like a brush to again gently remove any on the plant. Wipe all clean with a damp rag and let it dry an hour or so. I found that a paste made from Sulfur and water applied to the trunk and any exposed roots with a small artist brush really wipes out the growth. I do not leave it on for more than an hour or two and wash it off with a hose. Any paste leftover I sometimes mix into a solution that can be sprayed. I use that on the soil surface that is now exposed and re top the soil right over it. It will water trough and not hurt the plant - bonus it is anti fungal...
On the Juniper I mentioned there was also a lot of green coloration on the interior branches. I additionally watered the original paste I made down to more of a watery consistency using the same brush to paint green areas. For that we waited roughly 45 minutes and rinsed of the green along with the Sulfur treatment. Time varies but I wait until it has just dried. That day the wind was our friend as it has taken twice as long in the past.
I wrestled with Vinegar and toothbrushes a few years and mainly because the Moss kept returning - Sulfur is now my friend for what I call proactive treatment. That Juniper had a quite a bit of bark damage at the base from the Moss and we were lucky to remove it prior to actual trunk damage under the now "gone" bark.
Mileage does vary and Sulfur in paste will whiten the bark if left on to long so all I can recommend is to try it and keep close attention as you work.
Grimmy