The fruit of the Wangadi tree should be treated with respect, because if eaten at the wrong time it can be mind blowing.
"It was another beautiful sunset in the wastes. In the distance I could see an entire meadows worth of plants sliding to a safer place for the night." Exerpt: A Prospector’s Tale, VOL XXIII Blue Guild Press
"Just when I thought it could not get any hotter, we cleared the crest of a small hollow. There was the most magnificent sight, a huge shadey tree hidden in the depression. It must of been there for decades for I had never seen a Drooping Tree that large before and in my decades of prospecting since," Exerpt: A Prospector’s Tale, VOL XXIII Blue Guild Press
"Tumbling dang danger" the old old prospector said.
The ochre sands stretch for miles around. Something kicks up the dust. It’s a yak. A desert-yak. It ambles slowly, nuzzling the ground for the low-growing shrubs. The ranger freezes. “Stay very still,” he warns. “Don’t move at all.” “What is it?” you ask, breathlessly. “It’s the most dangerous creature in the whole Ocadian desert. And it’s about to eat that yak…”
A plague has hit the local area.
In humans it affects only the most vulnerable, the children and the very old, and even than it's little more than a summer cold. 24 hours of sniffles and then it's gone, barely noticeable really.
To sheep however it is fatal and the whole economy of the area is in serious trouble. If this keeps up the area could well be facing famine.
Somebody (enter the PCs) must find the rare herbs needed to make a cure.