Ludwigia rotting

[Lady Hobbs]

My Ludwigia was huge and growing out the top of the tank two months ago. Suddenly they all rotted off at the substrate. I pulled them all out today, cut the bad stems off and have them banded to see if I can get roots again.
I did not fertilize for 2 months but can't think of another reason for them to rot. Ideas?

[Wild Turkey]

what kind of substrate?

Sounds like you already know the most likely cause, but is anything else in the tank having problems?

[smaug]

The same thing happened to mine frequently.It happens because they are growing very thickly at the top and shading the bottom.Ludwigia are not exceptionally nutrient hungry but the 2 months could have contributed to this.It is actually best with luds to prune them regularly to keep them dense and compact.Do you remember the pics I used to post of my luds?They were extremely thick at the surface but looked truly awful just 6 " down the stems.Unfortunately the only way to keep them really low and compact is to have very high lighting and prune and clip the offshoots regular to encourage a branching growth.