What happens to a Merino Wool Tshirt thrown into the permanent press wash cycle?

The anti-stink properties of Merino are due to it's physical structure and chemical makeup, not due to something that has been added to the material. The only thing that's going to wreck this is detergent that hasn't been fully rinsed out coating the fiber. Also, washing 'wrong cycle' is more likely to damage the fit of the shirt than the anti-stink properties.

I'd check the tag on your shirt, most outdoor merino is machine washable / line dry, however much is machine washable low-heat. As I've mentioned the only danger here is to the fit of the shirt not to the anti-stink properties. I've stopped freaking out about whether my wife remembers to pull particular 'line dry only' merino (I wear it not just for camping) to air dry as when she drys it's always on low or super low heat… I've seen no damage to my 'line dry only' merino.

As near as I can tell, nothing, besides getting clean of course. My washer has only one wash cycle but three temp selections, so I always use cold for merino and a lesser amount of detergent than indicated on the measurer, then line dry. Regular wool will shrink but merino doesn't seem to do this. I once washed a Pendleton shirt that probably should have been dry cleaned, and it shrank down to a size extra small!

I have always hand washed all my Icebreaker gear by in specialized Merino wool wash. I'll use the machine, at most, to spin dry it, and occasionally use a fluff dry cycle to neaten it up after air drying. I take no chances.

My wife and I have been washing our Icebreaker merino wool t-shirts in cold water, permanent press cycle with regular detergent (Arm & Hammer unscented)for 2 years now. We dry flat per the instructions and find absolutely no negative affects.

Modern merino clothing that is made for outdoor use (eg IceBreaker) is a lot more resilient than your old-fashioned knit sweaters. It is designed to be machine washed and dried on low heat. For any other wool, you are best to wash and rinse it by hand in luke warm (NOT cold) water and lay it out flat to dry.

Yes you can wash good merino wool in your washing machine, however to me it would be like taking a baby to a car wash for his daily bath (weekly if you are from England)
I do it by hand and think of nice things when I wash my Icebreaker stuff.
Franco
Where is the love ?

I wash ALL of my tramping gear by hand. I don't trust our washing machine with my expensive stuff, and it doesn't really seem to rinse very well either. I also like to make sure things like my socks really are clean inside and out from mud, hook grass, etc…liquid wool/delicate detergents rinse a lot easier than powdered cleaners IMHO.

I don't baby them, but just throw them in with everything else on a regular cycle.. Can't be any worse what it puts up with on the trail/under my armpits :) I avoid the dryer though.

Ive been washing my icebreaker, smartwool, and montbell merino in normal cycle for years; each item has about 50 cycles on it. Certainly this wears out the fabric faster, but Ill live with that tradeoff. Antimicrobial properties seem to be intact.(smartwool better than icebreaker in that regard).
I drip dry them after the spin cycle.

I concur with most everything stated above about the care and feeding of Merino clothes. Using a mild soap is best but even the regular stuff like Tide and All work just fine. Line/Air drying is best but very low heat dryer tumbling won't really hurt it. Do remember to avoid using fabric softener. That would also apply to most of your camping clothing made of the new synthetics as well. I even rinse mine out in Alpine lakes and streams during most of my hikes. (Poor Fish!) My stuff looks and fits about the same as when first purchased.