josh wrote:

I planted an asparagus bed several years ago. In previous years unusual
events (wind storm, hail) kept me from making any judgments. But this
year I have no excuses. The plants came up pretty well and I harvested
some spears sparingly. All spring we've had plenty of moisture, but the
green foliage on all the plants uniformly seems to be withering starting
at the top and working downward. Right now the top 15 " of all the 4 foot
tall plants appears completely dead. Does anyone have any ideas?


google is your friend. I searched on "asparagus yellowing" and got a ton of
hits. This is one that might provide the answer you need. (It's possible
the yellowing is a lack of N)

http://www.hort.purdue.edu/ext/asprhu.html