Hi vvon I would not worry too much, IME it's what Dahlias do when they get a certain size. Mine always have hollow stems, and I just cut shortly above a node or junction. I never lost a plant because of a rotting hollow stem. I think that wasn't valid advise To my knowledge hollow stems are to be avoided when taking cuttings, but that means you need young shoots. So enjoy your plants, and if in doubt keep taking pics in case you need to analyze/ find a problem somewhen later. Have a great Dahlia season, bye, Lin

I know your addres says long island, but are you anywhere near corn plants?? Corn borer can do this. You can take one of the affected stems, and carefully slice it lengthwise, or, look for an entrance/exit hole along the stem

Terrisofla, I have the same problem with a few of my cuttings, they shrivelled up even though I mist them twice a day. This one in particular was spotting an inflo and I let it grow for a couple of weeks but the top just below the tip is hollow and getting more so by the minute, so I decided to cut the inflo off, but its still hollow, itt does get plenty of sunshine...any help or input is greatly appreciated!!! Thanks in advance. Nikki T

Carolyn, Thanks for your reply. I'm going to talk to the ag office, but I don't know if they can help. I had to leave on a business trip the day after I posted, so I didn't have time to make it to the Extension office. I got home yesterday and was mostly pleased to find that I haven't lost any more plants. But, I am wishing that I could find just *one* more infected plant, so that I could take it in! April