We don't know where you live Nancy so can't tell what the climate might be like. In some climates rhubarb dies down in the summer. I can only guess at insufficient moisture and too much heat but I might be way off.

Sounds like the plants are running out of steam.
This fall dig them up, amend the soil with compost, feed, and allow the roots to be frosted before replanting.
Preferably in a different spot. You'll kill off any pathogens and revitalize for next year.
Rhubarb likes lots of moisture.

Nancy, where I live rhubarb often doesn't last much longer than a few years. I need to replant mine in a new spot every few years to keep it going. The problem seems to be the long summer heat weakens the plant and something goes bad in the root system. The result sounds like what you are seeing.

Scott

Sorry, I forgot to put my location which is central NYS. We have had way too much rain, still can't finish tilling my garden. Could that be the problem? Also I haven't fertilized as often as I think I should. Thanks for the replies.

My rhubarb is not doing well either. I am guessing it has been the rain. The garden is unplantable, except in the raised beds.

nlpakk
I don't think it's too much rain. We've had 100% more than normal and my Rhubarb is super this year. I moved it and this is it's second year in the new spot, lots of compost for it's feet.

Rhubarb gets upset when it doesn't get rained on. Weak rhubarb is usually a sign of poor soil. Loose, rich, and damp from winter through June is key. Put a couple of inches of composted manure on top of the soil every autumn.

My two plants are in their 21st year and still going strong, but I have the advantage of a good rhubarb climate (Willamette Valley).

Water your rhubarb July-October monthly, especially young plantings with small root systems, or harvested plants lacking large leaves that shade the ground. Most people want rhubarb in May and June and forget about it the rest of the year. It is tough, but not indestructable.

Thanks for all your ideas!

I have now posted pictures of my rhubarb leaves on webshots. Hopefully someone will have a diagnosis. Here is the url:
http://community.webshots.com/album/5803311641mECNv

Here is a link that might be useful: Webshots

I believe I gave the wrong URL for my garden shots at webshots. It should be as below:

Here is a link that might be useful: webshots for nlpakk- garden

Hi Nancy - I looked at the pics and I don't think your rhubarb has a disease. I think it is a cultural problem. I notice you have them in a bed with healthy looking bearded iris. These plants have entirely different, in fact almost diametrically opposite, requirements and if the iris are happy the rhubarb will not be. Iris enjoy sunbaked, fast draining, sunny locations. Rhubarb likes deep, rich, moist soil and doesn't mind some shade. In the wild it actually grows along river banks. This Autumn I'd move the rhubarb to a position as near those conditions as possible and ensure it never runs short of water. Good luck.