Author Topic: Late Blight on Tomatoes  (Read 5135 times)

Silverleaf

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Late Blight on Tomatoes
« on: July 29, 2015, 06:36:27 »
Several (but not all) of the developing fruits on one of my Katja plants were brown this morning, looking worse at the stem end of the fruit and starting to go a bit soft. I whipped them off and disposed of them in the green bin. I'm assuming late blight, there was a full Smith period in my area yesterday and it's been damp for days.

The plant itself looks okay. No stem lesions, some lower leaves were yellowing and had little brown spots but they aren't fuzzy on the underside. I put those leaves in the green bin too.

This plant is one of 8 in my experimental straw bale garden. The fruits on the others (Snowdrop, Latah, Sandpoint, Coyote) look normal. Nearby potatoes don't seem to have blight (but I don't trust my ability to detect it so I stick to just removing any leaves that have any brown bits just to be safe).

So my question is, now what do I do? Do I need to dispose of the infected plant? Is it inevitable that the nearby plants will be affected too? I'll be totally gutted if I lose all my tomatoes as I've only had the first ripe ones from the greenhouse this week - two so far, with most of the plants yet to ripen anything.


Silverleaf

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Re: Late Blight on Tomatoes
« Reply #1 on: July 29, 2015, 06:38:25 »
The affected Katja hasn't been doing half as well as its greenhouse sibling, nor its sibling in a pot by the house. I'm not surprised it's the first to have problems.

Jayb

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Re: Late Blight on Tomatoes
« Reply #2 on: July 29, 2015, 07:06:31 »
Photos would be good if you have any or if any more start showing the same symptoms.

I'm wondering if it might be another show of BER, which doesn't always appear at the blossom end, sometimes rather than that dense black area it can appear to be a browning almost under the skin?

Late blight on tomatoes will most often infect first the leaves before spores move on to the stems and then the fruit.

Yellowing lower leaves is normally a sign of ageing leaves, the spots also or perhaps a feeding issue, harder to tell without pictures.

I've found LB strains seem to target either tomatoes or potatoes, (here it is most often potatoes first) but as soon as you get it on either one it is an indication that conditions have been ideal for Late Blight and further infections may have happened. If you had a Full Smith Period yesterday it would be too soon for infection to be showing from then, it would have needed to have taken place before that, often in the 5 to 10 day range, some strains of LB are more aggressive and can work quicker than others.

If you have a suspect leaf, take it off, dampen it and seal it in a plastic bag. place it somewhere warm and check in 8-12 hours, it should be more evident if it is LB as it will multiply rapidly. If you have removed any suspect looking leaves, just keep picking off anything you think is iffy, tomatoes will often be ok as long as it has been caught early on and keep an eye on your potatoes for symptoms.

If the Katja plant has been struggling perhaps a sign of some other problem and a good sign as LB does seem to target the healthiest and best plants!

Sorry you are having problems and hope it isn't LB.
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galina

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Re: Late Blight on Tomatoes
« Reply #3 on: July 29, 2015, 07:41:10 »
As Jayb said .................

Sorry to hear about your problems.  If it is blight, it will be on leaves first, stems and fruit later.

Just one more point to add.  Every leaf pruned is a little wound for the plant.  Make sure you prune at a time when the patch can dry over (not last thing in the evening for dew to add to the moisture problems or during actual rain).

Hope it is just this one plant and hope it is BER rather than LB.  Good luck.

Silverleaf

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Re: Late Blight on Tomatoes
« Reply #4 on: July 29, 2015, 08:07:38 »
Well I'd much rather have BER than LB, so fingers crossed it's that. I'm pretty sure it's come on over the last couple of days, but as you two say that stems are affected before fruits it might not be LB after all.

When I planted out the Katjas I picked the best of the three for the greenhouse, the second best for the pots near the house, and the other went in the bales simply because I couldn't bring myself to throw it away and I thought I'd see how it did in straw. Similarly there's a "spare" Coyote and a Latah in there, none of which are very big. The Sandpoints and Snowdrops look better.

Both of the other Katja plants have had a brownish patch under the skin on the side but don't seem to be rotting or anything, and the greenhouse one is definitely ripening on that side.

Another thing I noticed about the dodgy fruits - one of them was a megabloom fruit so made up of several "sections". They normally kind of fuse together to make something that's mostly tomato-shaped but a bit weird-looking, and this one was just like that a few days ago. This morning the segments seemed to have separated quite a bit so it looked really weird and lumpy, with darker brown in the ridges.

I really wish I'd taken pictures now! But I'm not rooting around in the green bin... ;)

Thanks for the help. :)

Silverleaf

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Re: Late Blight on Tomatoes
« Reply #5 on: July 29, 2015, 09:33:07 »
Okay, this fruit didn't look so bad as the others so I left it on. The ones I picked off were much more extensively brown than this, but it shows the separation of the megabloom fruit quite well.

Does this help at all?

galina

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Re: Late Blight on Tomatoes
« Reply #6 on: July 29, 2015, 09:50:35 »
This looks like BER,possibly coupled with heat damage and rain damage.

Extensive 'knife work' needed at eating time, but I do not think this is blight damage. 
There is a lot on google about Epsom Salts and BER prevention.  However BER tends to be an early season thing and may clear up by itself.


BTW, I had several 'cooked' gooseberries this year, which turned brown afterwards.   I took the glassy, heat damaged part off, but the rest of the berries tasted very off.   Luckily it was only a few.

 Hope you can trim these tomatoes when they ripen and they will still taste ok.   
 :wave:

Ellen K

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Re: Late Blight on Tomatoes
« Reply #7 on: July 29, 2015, 10:41:03 »
The picture looks more like cat facing than BER.  I say this because with BER, you do see a rotten bottom to the tomato but with catfacing, it's a deformity due to low temperatures when the fruits are forming.

I gave up trying to grow beefsteak tomatoes outside because they were particularly susceptible to this.

But I am no expert. 


Silverleaf

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Re: Late Blight on Tomatoes
« Reply #8 on: July 29, 2015, 10:50:26 »
The slight mushiness at the stem end of the really dodgy fruit along with the brown colour all over was what had me convinced it was blight.

I guess BER could have easily been caused by the recent rain after a fairly dry spell. Heat hasn't really been much of a problem here the last few weeks! The max temperature has been 17C.

The Sousulka Chernaya in the greenhouse has some BER on the first and third trusses, although the second has miraculously escaped it so far. It's the usual black shrivelled base thing. I noticed it weeks ago but the affected fruits don't seem to be getting worse so hopefully they'll still be mostly edible.

Silverleaf

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Re: Late Blight on Tomatoes
« Reply #9 on: July 29, 2015, 10:57:26 »
Oh yes, catfacing, I'd forgotten about that Ellen. That's definitely possible. And Katja is a large-fruited type so I guess it would be more susceptible to that kind of thing.

Fluctuating temperatures, definitely a thing here the last few months...

galina

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Re: Late Blight on Tomatoes
« Reply #10 on: July 29, 2015, 12:49:18 »
EllenK, I think you've got it pinned down accurately.  Catfacing rather than BER and splitting afterwards due to weather.  Have just found a picture that looks very similar to your tomato Silverleaf.  Have a look, what do you think?
http://www.lcnews.us/gardening052407.htm

Silverleaf

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Re: Late Blight on Tomatoes
« Reply #11 on: July 29, 2015, 20:23:57 »
Yes, I think so. Perhaps the really dodgy ones had both catfacing and BER?

Ellen K

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Re: Late Blight on Tomatoes
« Reply #12 on: July 29, 2015, 21:36:50 »
I grow F1s mostly and they don't get catfacing but someone gave me a Latah plant this year and some of the fruit show it .... see picture.  Though the fruit are still fine to eat.  The leaves are from tomatoes and potatoes which have what I believe to be early blight.  I've cut the leaves off as it has appeared and it is quite benign compared to late blight.

BER - well I've grown tomatoes with that too, and it is quite distinctive and definitely rot.  You would not want to eat it.

Silverleaf

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Re: Late Blight on Tomatoes
« Reply #13 on: July 29, 2015, 23:41:38 »
My outdoor Latah plant has a lot of weirdly-shaped fruit, and there are a few on the two in the greenhouse too, although they are mostly normal-looking. I don't care though, they taste fantastic!

I'm not planning to eat the rotted bits of BER tomatoes, but I'm hoping the affected ones won't get worse and I can just cut that bit off, if they aren't too bad.

 

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