My rhubarb is stressed and losing leaves.  What do I do?

Question: I have a rhubarb plant in my backyard that is really important to me. (The mother plant originally was in Iowa on my grandparents' farm from the 1940s.) I transplanted a divided section last fall and planted it in my yard and it's been doing well up until about a week and a half ago. The leaves are yellowing, have holes in them, and are dying off but the plant is producing new stalks. I'm worried the plant is dying and don't know what to do to save it. Please advise.I put a bag of manure around it earlier this spring, and provided a generic vegetable fertilizer about two weeks ago. It gets watered via the rain we've been having plus supplemental water from our smart lawn sprinklers. The soil under the plant has been very dry still. I've noticed a lot of ants and earwigs on the plant and sprayed it with veggie safe insect soap. I haven't harvested it since I planted it.

responder: Arapahoe County Extension  Replied July 17, 2023, 4:15 PM EDT
response: Sati We are sorry to hear and see the condition of your rhubarb. We certainly understand the importance of this plant to you personally. This is a new plant in your garden and then we had an unusually wet and cold spring with very hot weather now. These are important factors effecting the condition of your rhubarb. Additionally, it does appear that you do have an insect feeding on the leaves.  Rhubarb doesn't have a lot of insect pests, but the two most common ones are rhubarb curculio, or rusty snout beetle, and slugs. Black spots on the stems of the plants indicate rhubarb curcolio; jagged holes indicate slug or snail activity. Control the beetles with rotenone or pick them off by hand.  It would be very helpful if you would carefully investigate the presence of what is eating these leaves. Take a picture of the bugs or insects, and email us those pictures, that would help us to determine the best way to treat your rhubarb.  There are multiple factors involved here. We do want to assist you in saving this plant if possible. We will look forward to having your reply to this email at your earliest convenience.    Ellen Barry and Courtney Cowgill, CMGs

responder: The Question Asker Replied July 17, 2023, 9:49 PM EDT
response: Hi Ellen and Courtney,

I greatly appreciate your prompt reply and all the information you provided.  I don't see any insects on or around the plant aside from earwigs and ants.  I don't see the black spots on the stems either, though one stem does have some scarring down the length (pictured).  I did have slugs completely demolish hostas a few years ago; that seems very reasonable that they may be eating the rhubarb too.  I haven't seen them, but I've been tending to the plant during the day.  

Please see the attached additional photos of the leaf damage and close ups of the stems.

Thank you again for your help!






On Monday, July 17, 2023 at 02:15:24 PM MDT, Ask Extension <ask> wrote:</ask>

responder: Arapahoe County Extension  Replied July 19, 2023, 2:38 PM EDT
response: At this point we think the best course of action would be supportive care. This means light watering every 2-3 days allowing some drying between watering.  Watch for insects after cleaning up around the plants. We believe that you should remove the dead and diseased leaves and dispose them. Encouraging things are that the stalks themselves look pretty good and it seems like there is some new growth in the middle of a plant in your picture.  The earwigs could be some of your problem. You can treat by spreading diatomaceous earth around the base of each rhubarb plant. The insects don't like crawling through this irritating but natural powder. You can buy this at greenhouses or at agricultural feed stores. Further fertilizer is not recommended at this time.   We would like to hear from you in the next weeks to see how the rhubarb is doing.  Ellen Barry and Courtney Cowgill, CMGs

responder: The Question Asker Replied July 19, 2023, 2:58 PM EDT
response: Thank you so much!  I appreciate your advice and actionable items and will remove the dead leaves, purchase diatomaceous earth, and water every 2-3 days.






On Wednesday, July 19, 2023 at 12:38:32 PM MDT, Ask Extension <ask> wrote:</ask>