Thank you for contacting MSUE's Ask an Expert.

Your white hosta petioles are a mystery to me.  It appears that the leaf petioles (stems) have a fungal disease.  Can you tell me what cultivar your affected plant is?  Was it a newly purchased plant or merely a transplanted one?  Are there other hostas in the area where this one is planted that are not affected? 

Our weather this summer has been ideal for growth of fungal diseases, which are prevalent in warm, humid weather.  Their spores are spread by splashing rain or irrigation, wind and insects. There are some maintenance tasks you can do to minimize fungal infections, i.e. be sure your plants are not crowded and have good air circulation, and clean up exhausted foliage at the end of the season.  Do not compost diseased plant material. 

Botrytis is one fungi that attack hostas, and can kill the plant.  However, your plant doesn't exhibit the usual symptoms of broken stems at ground level and dying leaves. Your hosta doesn't appear to have that problem.  Just so you can check it out, look at this site which discusses most of the diseases known to affect hosta:

http://www.plantpath.iastate.edu/files/SUL14.pdf

I have been unable to find any research-based information on your hosta issue.  I'm wondering if it is a mold that can be washed off.  I guess if it were my plant, I would dig it, pot it and isolate it while I experimented with a cure.  Sometimes spraying with soapy water can kill mold.  I do notice that this hosta has blue leaves, any soap or other chemical may remove the blue coloration for this year's leaves.

If you have any additional information you can send me, I will keep investigating the issue and see if we can come up with something to help.

Again, thanks for contacting AaE.

thank you, Sharon, for your help and the link to the hosta pests site.  I don't know the type of hosta. I've had it for several years and just a few weeks ago divided it and transplanted in a new area of my yard, maybe too near a sprinkler head.  the two other cuttings from the same hosta are just a few feet away and have (so far) no sign of the fungus.  I'm concerned enough that I think I'll just dig this one up and destroy it.  one more thought...  the hosta is near a woodpile where our neighbors have stacked a lot of wood from a couple ash trees that had to come down because of ash borers... any possible connection there??

thank you, Sharon, for your help and the link to the hosta pests site.  I don't know the type of hosta. I've had it for several years and just a few weeks ago divided it and transplanted in a new area of my yard, maybe too near a sprinkler head.  the two other cuttings from the same hosta are just a few feet away and have (so far) no sign of the fungus.  I'm concerned enough that I think I'll just dig this one up and destroy it.  one more thought...  the hosta is near a woodpile where our neighbors have stacked a lot of wood from a couple ash trees that had to come down because of ash borers... any possible connection there??

If you aren't terribly fond of this hosta, I'd say destroying it would be the best course of action.

No connection to emerald ash borer.

There is one other remote possibility, but I didn't mention it because I don't believe it is your problem. I found a cluster of white fuzzy blobs on the stem of an Asiatic lily yesterday.  The white guys are immature leaf hoppers.  I've never seen them as thick as what you have on your hosta, nor have I ever seen any brown coloration.  I'm still thinking you have a mold of some kind.  Be sure to destroy the plant before the next rain, so spores don't spash on neighbors.

I've attached a picture of the leaf hopper dudes FYI. I hope it's not too large to transmit.  If you don't get my pic, you can google for immature leafhoppers and probably find a picture. Thanks again for contacting us.