I found the golden rod.

[meh]

The only thing fishy about the screenshots is that he has all 7 perks, and I'm pretty sure it caps at 4. Anyway, the golden rod can be found at the base of the lighthouse. After getting the green light on the submarine you have to use the VR11 to turn a zombie into a human at the base of the lighthouse who will then be sucked up into the light.

After a while, you'll hear a generic "glowing" sound and the golden rod will appear at the base of the lighthouse.

[dubistot]

To get the Golden Rod, lure a zombie to the bottom of the lighthouse and shoot it with the Vr-11.

Once its in the green light, quickly shoot it with the Scavenger(Sniper). If done correctly, the golden rod spawns at the bottom of the stairs.