Before I had a chance to set up drip irrigation I was doing some overhead watering, trying to aim for the base only. I think that caused it to rot. Can I salvage by cutting below where it’s damaged or do I need to chuck the whole tuber? 😭
by gremmygrems
4 Comments
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I’ve had success cutting the stem out of the crown. I try to make sure I get the eye out so it doesn’t spread.
I’d pinch out the middle and take a cutting. Then cut down the rotting stem to the tuber.
Watering the leaves of dahlias is fine and in fact can be a valuable technique; see, for example, [https://triplewrenfarms.com/how-often-should-you-water-your-dahlias/](https://triplewrenfarms.com/how-often-should-you-water-your-dahlias/). But you should generally do it early enough in the day that the water can dry and you don’t encourage powdery mildew.
However, what you have here is black stem rot, not powdery mildew, so that is all beside the point. The bacteria or fungus causing the stem rot gain a foothold from overwatering. They may have been present because the potting medium was unsterilized or maybe some unsterile compost was added. Now that it’s in the soil, your best bet is probably to remove all of the diseased parts of the plant and repot the tuber in a 100% sterile peat-based potting mix.