Even the remaining sticks & bark on existing PI plants w/ no leaves will contain the urushiol oil that causes the irritation to susceptible individuals.
At WyCo: I didn't do it last year, but for several years previously I went after the areas where there was a lot of undergrowth that would quickly evolve into overgrowth with a weedeater and a pair of disposable sweat pants. Ivy Block is useful here, but not 100% effective.
These were higher traffic areas where I thought many a disc would land due to 'common' errant shots...specifically hole 4 near the creek, hole 7 when short-right, hole 9 near the creek, 11 short pin area, 17 short, etc... Areas with a steep drop-off (IE holes 10 & 12) I would hit what I could, but didn't want to be flinging PI juice towards my shoulders and above. Early-mid May
is a great time to have an impact that is moderately effective for the rest of the playing season. Not talking about eradication, but controlling the PI and much of what else pops up. By knocking it down this early, I'd say that much of it doesn't make it back...but of course, not all of it. The new PI is less than 1' high at this point.
While I'm not as allergic to PI as when I was a kid, it was a given that I'd get some rashes anyways from the above procedure. I don't do this anymore, so don't ask me to.
But if there's someone who knows they don't get PI, this early-mid May time-frame
provides a chemical-free alternative toward the jungles that will
form come June/July/August.
What is cut down by a weedeater is still active, so setting your DG bag down in it, or dragging your towel or DG bag straps can/will contribute to future outbreaks.