Geranium Stems Are Black Inside!

[Antxiara]

Hello Everyone!

I have have been gone a month from my home and someone has been watering my plants. When I got home I thought since it had been very hot and dry that my geraniums had dried up...but there was still some green parts so I just started trimming the dry parts. However I see that there are like black holes and the inside of the stems are black...looks like fine wet soil. I can't see any pests. I looked online and well it doesn't look like stem rot but I'm not sure. Anyone know what it is and if it can spread to other plants?

Thanks in advance!!

[applestar]

The holes with blackened "sawdust" inside suggested stem borer of some kind so I searched and came across this. Have you seen moths like this flying around?
https://en.wikipedia.org/wiki/Plume_moth
Geranium Plume Moth (Amblyptilla pica)

...I have to admit I have! I never ID'd them before, but now I know what they are, and what mischief they have been up to.

[Antxiara]

I haven't seen any moths or insects...that's why I'm so lost on what it could be. Maybe there were moths and they have left?

[imafan26]

I get that too. They are borers and usually you will see a small hole on the stem. I never see the moth because they usually come out late in the evening. Over watering can also cause rot. Geraniums should only get watered when the soil is nearly dry.