|MY DAHLIA BULBS GROW UP GOOD. NOW THE LEAVES HAVE WHITE SQUIRLEY MARKS ON THEM AND ALL THE BULB'S END UP TURNING BLACK AND NOT FLOWERING.|
|I'm concerned that your description sounds suspiciously like a virus. Here's a web address with photos of virus-infected dahlias:
If your plants look like this, you might want to read the information contained in the rest of the site.
Best wishes with your dahlias!