[russellcm]

Hi,

I’m pretty new to this growing lark having taken on an allotment plot about 9 months ago. Until today  was quite happy with how my tomato plants were doing, they have plenty of fruit on them although none have ripened yet. However today I noticed dark blotches on the stems, some of the leaves and some of the tomatoes. Gutted. 

There are about 22 (4 different types) plants all in the same area. Tomatoes weren’t grown there last year. I’ve attached a photo, please take a look and help a novice!

I have several questions:
1. What is the disease?
2. How should I treat it?
3. Should I dig up the affected plants (currently about 5 or 6)?
4. Has the wet summer contributed to this?
5. I’ve been a bit slack and left a big bag of rotting weeds close to the plants – could this have contributed?

If you are able to answer any of the above that would be great.

Thanks in advance

Russell

[russellcm]

Here's another pic.

Thanks

[viettaclark]

I'm afraid it's late blight Russel.
Dig up the affected plants and burn or put in a sealed black bag in the sun until it's all dead and rotting. Be careful not to shake the plants too much and get them away and contained asap. Any unaffected fruit could be brought in and ripened on a window sill but immediately bin any that develop the brown patches.
If you have plants that are clear at the moment keep a watchful eye on them (every day....blight spreads very fast!) and if leaves develop the tell-tale marks snip them off immediately and bin them, Stalks are more difficult and you might have to bin more plants if you can't cut it out.
Blight is caused by spores travelling on the wind then finding damp areas on tom/potato plants to settle and grow in the humid warmth. The spores kill the plant tissue very quickly.
With the weather we've had it's really bad this year and much earlier than usual so fruit isn't ripe. Last year I managed to save most of my crop because it didn't hit until early September and I quickly cut off the fruit and ripened inside and binned all the plants.
This year I'm talking from experience.....potatoes affected and 60+ tom plants that started flowering late and so far I've had to bin 20. But I'm snipping every day so it's still spreading and I really don't think I'll get a crop....the first trusses are just forming and I expect all the plants will succumb......
Nothing else you can do now.

[surbie100]

I've had the same - most of my plants on the plot have gone. I've kept a few plants on my balcony and (touch wood) they are still ok.

Are your neighbours growing toms/potatoes? Mine have left their blighted potatoes in for ages. Is really frustrating - while they might not be to blame for my blight, it can't have helped.

Really sorry you've got it.

[mumofstig]

You can help prevent blight on tomates/potatoes if you are prepared to spray.

It's discussed here 
http://chat.allotment-garden.org/index.php?topic=71373.msg814371#msg814371

[JayG]

Sorry to hear that Russell - blight is a nasty disease that spreads very quickly and with tomatoes in particular can leave you with nothing.

The weather this summer was always going to provide ideal conditions for blight, especially outdoors, so you need some luck, but also need to make sure you don't inadvertently tip the balance against your crops.

Blight spores can't germinate on dry leaves, and although you can't do anything about rainfall, you can make sure you only water the plants at the base. Leaves which touch each other (or the greenhouse glass if indoors) tend to trap rain and condensation and increase the local humidity - thin them out but make sure you wash the scissors or secateurs especially when going from an infected plant to what appears to be an uninfected plant.

Take out all obviously infected stems and put them in a sealed bag in your domestic waste - if in doubt remove the whole plant.

Hope you manage to save some of your crop.

[viettaclark]

I thought walk-in polytunnels were the way to go but you can still get infection from blight because you need to ventilate and go in and tend the plants.
Can you imagine a scenario with a defumigating area next to your tunnel and having to put on all the gear (plastic booties, suits and hats) to go in and weed your toms!!!!!
I saw an interesting prog last night about food production....mainly strawbs, apples and toms and basically they all use preventative sprays except the organic growers who can lose a whole crop to pests and diseases.
At least I'm not making a living doing my growing.
Just very very disappointed this year........

[surbie100]

You can help prevent blight on tomates/potatoes if you are prepared to spray.

I've been using bordeaux mix, still got blight on toms.
a) it's only preventative
b) I'm a newbie and my toms are were planted too closely together.

Next year I might have a house with a garden and my toms will go there.

[russellcm]

Thanks for all the advice everyone. Will get down there tonight and see what I can salvage.

I think I probably planted mine too close to each other as well. I should have stuck with what Dr Hessayon wrote in the Veg & Herb Expert rather than listen to the lady on the plot opposite who told me I didn't need to plant them that far apart!

Live and learn

[russellcm]

Just had another thought - about a week or so ago I dug up the last of my second early spuds and wonder whether they had blight and I have spread it to the tomatoes. They are as far as possible apart from each other on my plot but that could be what happened.

Hope that's not the case and my spuds don't start rotting now.

[ilan]

I think its just one of those years I have got it on the toms in the poly tunnel and doubt I will get much from them Fortunatly I also planted three toms in a greenhouse that were sown as part of the early experiment and I am having some ripe fruits of those and touch wood 

[viettaclark]

Just noticed for the first time why blight tends to start on the bottom edge of the leaves. The leaves curl up slightly at the tips so when it rains the water sits on the end of the leaves long after the rest of the plant has dried out. Blight spores blown by the wind attach themselves to the damp area, multiply and spread. That's also maybe why the stalks tend to start rotting at leaf joints.
Shame we can't spray the plant with cling film stuff!! Obviously daft because it's got to breathe..... ....but maybe I'm onto something.......breathable cling film spray......that would sort out loads of pests and diseases........
(Think I've been watching too much lycra in the Olympics!!!!!! I'll get my coat.)

[viettaclark]

I have been thinking and thinking about this blight problem and when another patch appeared on a low leaf joint where I'd removed the leaf I decided to try and save the plant rather than cut it down.
I reckoned some kind of barrier cream to seal in the spores to stop them spreading and cut off the air so they die.
Vaseline? Undiluted washing up liquid? My anti- microbial emolient cream?
I decided on Canesten. It's an anti fungus/yeast cream so might even kill the spores too.
You might think I'm mad but watch this space!!!
(Just spoken to someone and they said what about Athlete's Foot powder but it's not a cream to stop the spread)
.......you'd think there would be some kind of treatment wouldn't you with blight being so destructive?

[Yorkie]

And I have to repeat the standard response to any suggestions of using unlicensed and therefore illegal products as plant pesticides.

The forum cannot endorse or condone such behaviour.

[viettaclark]

Sorry Yorkie. Didn't think about that at all when manically investigating possible "fungicides" found in the home.
What are the rules on this? Is it using something that isn't licensed for plants and/or is it putting it on the site?
Either way, again, please accept sincere apologies for ignorance.