andy39surf wrote:
Hi don't know if anyone can help here. I'm a new gardener this year and
am growing tomatoes in pots in a courtyard gaden. I have attached pics
of 2 of my plants which from research on the net I suspect to have stem
rot. There seems to be a lot of conflicting advice on what to do, so I
thought I'd post here.



It's definitely some type of rot (perhaps Pythium Rot or a form of
Blight). Either way, from my experience, the affected plants are doomed.
I lost twenty plants to something similar a few years ago. There could
be a number of sources but too much moisture/humidity could be a factor
that allows the fungus to thrive. I had to destroy the entire crop
because it spread so quickly. (I see you're in the UK, so your climate
is not unlike mine in Eastern Canada - cool and moist...ideal for fungus
to grow).

One thing I'll note from the picture is that you need to mulch the
plant. When you water them, the soil gets splashed up on to the leaves
and stem and that contributes to the spread of soil-borne diseases (like
Blight).

Right now, you have to pull those plants and either burn or garbage
them. Do not use any part of the plant or soil in your compost. You'll
only pass on the disease. Do not reuse the soil in anything that may
eventually host future tomato or potato plants. I usually put the used
container soil on the lawn as far from the garden as possible. (This
applies to tomatoes and potatoes regardless of whether a disease appears
or not...a disease may not affect one season but overwinter in the soil
for next season).

The next time you plant tomatoes, use new potting soil (every year) and
mulch the base of the plant. When the plants get so high (as in the
pics) you might consider a light dusting of a fungicide (if you have any
surviving plants that haven't shown the stem rot yet, consider a
fungicide dust to see if you can save them). I have a moist climate here
and always give a sprinkle of potato dust on my tomatoes and potatoes. I
haven't had a fungus problem since. Also, keep the plants away from each
other. They don't look like they were touching in the pics, but just in
case, ensure the leaves of each plant have enough distance so that
they'll never touch. And don't over water them. The soil should feel
damp and moist, not saturated.

That's my take on it anyway. I'm quite interested to see what others
have to say.

..

Zone 5a in Canada's Far East