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Paulownia Seedlings - Stem Rot

Posted: Thu May 24, 2012 10:56 pm
by Kristen
Two of my Paulownia seedlings have rotted at the base of the stem. Is this common?

I've switched to watering them from the bottom.

I am raising so many plants this year that everything is getting slopped with water, rather than TLC, so that may be the cause & effect, but they haven't been sitting in water that I know of.
Paulownia seedlings in 1L pot
Paulownia seedlings in 1L pot

Re: Paulownia Seedlings - Stem Rot

Posted: Fri May 25, 2012 9:37 am
by Vagetarian
I don't know anything specifically about Paulownia's so I could be off the mark but 1L seems awfully big for a little seedling. 1L of compost should hold around 1/3L of water (in my experience).

Personally speaking, I would have put them in a tray of 6cm square pots with up to 50% (probably 33%) perlite. At this point when one pot dries out you can soak the entire tray without over watering the rest too badly. I usually let the first one or two plants in a tray start to droop before I soak the lot, though Paulownias may not accept that.

Of course, this is not to say that I haven't over watered a plant in a small pot of 50% perlite when the conditions weren't right...

Re: Paulownia Seedlings - Stem Rot

Posted: Fri May 25, 2012 12:36 pm
by Kristen
Vagetarian wrote:1L seems awfully big for a little seedling
I should have said "from seed" rather than "seedlings" !!

They were pricked out into 9cm pots, and then potted on to 1L. Probably not apparent from photo but the batch in 1L pots are now a bit more than 2' tall, the one in the photo was about 18" before starting to keel over a few days ago.

When I potted on to 1L one of them was small and I left it in the 9cm - that one has since got stem rot - so they are getting quite big / long after potting on for it to be damping-off I think?

It looks like what happens to my Cucumbers if I top-water or slosh water on them ... they are very prone to stem rot ... and what with our cold Spring there is every chance they have been "cold + wet" at some point.

Their potting mix is M.P. compost + Perlite. (I hear people say 50%, but IME that much means that it doesn't hold any water at all! I use that sort of ratio for cuttings, but for potting on I put enough in that it keeps the compost "open" and stops it compressing so easily (compared to trying to just use M.P. compost on its own which forms an algae crust and there is no air in the mix and then the plant fails to grow at best or keels over at worst :( )

Re: Paulownia Seedlings - Stem Rot

Posted: Fri May 25, 2012 1:01 pm
by Vagetarian
Ah, my apologies, I thought it was a few inches. (Which was to be honest a little confusing because having read a lot of your posts I didn't think you'd put a seed in a 1L pot, since you probably have about 3000 of them. :lol: )

I don't know but I would think that given the right conditions some (or all) of the various fungi that are known as 'damping off' would be able to attack and kill a mature plant, perhaps if it was weakened. Of course it's then not 'damping off' because it's a term that's specific to seedlings.

One particular fungi that's responsible for damping off is Botrytis (grey mould) and we certainly know that attacks mature plants.