asparagus problem

[staris]

i planted some 1 year old asparagus crowns this year and they have been growing well the ferns are about 4' high.
one of the plants isn't looking so good about 3 weeks ago the fern went all dark and woody and died, then up came another spear and it to is starting to die , none of the others are affected that i can see, it's very well draining soil so it's not that, any ideas as to what it maybe and i wonder if i should take the plant out.

[staris]