Dead Sprouts

I bought 4 Willamette rhzomes off eBay about 2 weeks ago. When they arrived 3 of them had 1-3 inch white sprouts on them. I planted 3 of them in my yard a week ago and left one in the fridge for my coworker who is currently on vacation. I received 2 more (Kent Golding and Brewer's Gold) in the mail eariler this week, but hadn't gotten around to planting them until today.

At the suggestion of the family gardening guru (my grandmother) I picked up a bag of root stimulator at Lowe's. I decided that since the Willamettes that I planted hadn't sprouted yet it'd be worth my effort to dig down an inch or so and get those some root stimulator too. Well what I discovered were brownish and apparently rotting sprouts. Is this what you might expect to see if the soil ph was off? Should I buy a test kit?

The 3 rhizomes that I planted today are in pots with black gardening soil, so they should be safe.

EDIT: If I pull the Willamettes out, rinse them off and plant them in good, dark garden soil do you think they'd bounce back?

Rot tends to be fungus. I'd cut off the rot and wash the rest in a mild bleach solution before replanting in good, well-drained soil.