Big Pink Tree Saves the Day

Dr Keto
Medibay
About an hour after this snip...
---snip---
The tree looked sceptical.
"Hey, I'd like to see you do better!" challenged Keto. He was
somewhat surprised when the tree nodded, and turned towards the main
laboratory...
---end snip---
"So that's it?" asked Dr Keto, staring at the two bottles the tree
was holding, "An hour's work, two bottles and you think you've
developed a cure for this epidemic?"
The tree nodded, leaves brushing against the ceiling.
"Fine. Great," sighed Keto. "So...what's that for?"
He pointed towards one bottle that the tree held - a spray bottle
filled with some light green liquid. The other hand (read: branch)
held a similar bottle containing a red liquid.
The tree pointed towards the green bottle, then towards Keto. Then
it pointed towards the red bottle, then towards itself.
It took Keto a couple of seconds to get it.
"Oh, you mean that the green liquid is to be sprayed on the real
people, the red one on the hallucinations?"
The tree nodded again.
"What about the people who aren't sure?"
The tree shrugged (a difficult move when you have knotholes for
shoulders) and gestured towards the now evaporating puddle on the
floor.
"Point taken," agreed Keto. "Here, I'll take the red bottle. You
spray the people outside, I'll spray the hallucinations, okay?"
The tree nodded for a third time, then unexpectedly sprayed Keto.
The doctor spluttered.
"Hey, what do you...!" he began, then coughed and blinked. He
suddenly felt very much healthier. In fact, as he glanced up towards
the centre of the room where, moments before, Max Strength Ointment
had still been spinning, he saw that...there was nothing there.
HE WAS CURED!
----Twenty Minutes Later----
The tree and Dr Keto, both exhausted, returned to the office as the
crowds dispersed from the medibay outside.
The liquids had worked quite well, relatively speaking. The
sprayed people had suddenly straightened up, stopped complaining and
apparently stopped seeing 'their' hallucinations.
The sprayed hallucinations, on the other hand, had straightened up,
stopped complaining and apparently stopped seeing 'their'
humans...before dissolving about thirty seconds later.
Of course, it had been too optimistic to hope that both humans and
hallucinations would be affected the same way.
"Well, Mr Tree, that was very satisfactory," nodded Keto, turning
to face the big tree. He glanced down at the bottle. There was
still some red liquid left in it. Keto had sent to revived Dr
Ventrite down to engineering with a sample of the green liquid to get
it released into the air vents, presumably curing the crewmembers.
Keto brandished the little red liquid remaining.
"Goodbye, Mr Tree," he said. The tree cowered as Keto raised the
bottle, and made a faint whining sound.
"Oh stop crying!" snapped Keto, "You made the damn stuff!"
The tree continued to mourn. Keto hesitated, his conscience
bothering him. Did this tree actually constitute a medical threat?
=============
Should Keto kill the tree?
Will there be any unexpected side-effects to the tree's treatment?
What effects will the green liquid have on those who are immune to
the hallucinations naturally?
Find out in the next episode of Blue Dwarf!