Sunday, 17 January 2010

dreaded wilt

From a distance my tomatoes are doing really well.  Including the pot they're now as tall as me!
http://www.alexareynolds.com/garden10/tomatoesjan.JPG
And the Tommy Toes harvest is going crazy.  Look at all these little beauties!  I made a great little tomato and quinoa tabbouleh with dinner tonight.  Scrumptious!
http://www.alexareynolds.com/garden10/tomatoharvestjan.JPG
But look closer and not all is well with the tomatoes.  Ever since last week's hot spell, more and more leaves have started to die off from the bottom of the plant upward. They start out yellowing in blotches like this:
http://www.alexareynolds.com/garden10/tomatoleafsick1.JPG
And quickly half of the leaf dies off like this:
http://www.alexareynolds.com/garden10/tomatoleafsick3.JPG
Before the whole leaf shrivels and falls off.

It's the common and dreaded fungus fusarium wilt.  The fungus essentially clogs the pipes of the plant, starting from the bottom.  It chokes it of water and nutrients and there's no real treatments for the backyard gardener except raising the pH of the soil and prayer.  It especially thrives in warm temperatures (check), the plants can appear generally a bit limp (check) but appear to "recover" overnight (check).  This limpness causes gardeners to water them more (check), and the dampness just encourages the fungus.

The only symptom they're not showing is in the stems.  They're meant to show a ring of brown, dead tissue inside but when I checked one stem it's still looking healthy.  Perhaps the brown appears in later stages of the disease.
http://www.alexareynolds.com/garden10/tomatostemsick.JPG
So now I'm just hoping I can get as many tomatoes from it as possible before it dies, especially my rouge de marmande.  There are now several that are a lovely reddish-orange but the shoulders are still green so I'm giving them another few days.

The mystery is how they could have gotten this disease.  It's generally soil-bourne which is why you're not meant to grow tomatoes in the same place two years in a row.  But they're in a new pot with new potting soil.  It could have come from my trimming shears, I don't sterilize them as much as I should.  Or it could have come with the seeds, which I got from another tomato grower.  And the fungus spores hang on for a long time, which means I have to throw out the potting soil (which isn't cheap!) and figure out a way to sterilize the pot before next year.  And maybe stick to a variety that's resistant to fusarium wilt.

4 comments:

prue said...

I am convinced fusarium is the culprit that wiped out all my tomatoes this year, all grown in pots. I am currently trying to grow resistant varieties to check it is this wilt as I couldn't see the brown in the stems either. Hope you get a decent haul before the vines are taken over completely.

Funkbunny said...

I'm pretty sure I have this too :( Annoying isn't it? My plants don't wilt though but leaves look just like yours. Will check the stems..

GM said...

This looks very like what I've got. Yellowing lower leaves, and in the advanced stags, wilt sets in, with consequent crisping of the wilted leaves, if the sun is hot enough. I thought it was verticilium wilt, since this likes hot dry weather, has similar symptoms, and only has the brown stem ring in the lowest 10-15 cm. I pulled up 2 plants today, no brown ring on the surface stems, but where i had planted them deep, there was a slight discolouration in the vascular tissue 3-4 cm below the ground.

Jake McCann said...

I have two tomato plants with the same symptoms. The symptoms started in late January during Adelaide's hottest weather. They have not recovered despite daily watering.
I had planted two store-bought seedlings in potting mix. This is the first time I have grown tomatoes, so I guess the disease must have been in the potting mix.

I am still getting a small amount of fruit from the plant - but only from the few younger, still green shoots.