Tomato Blight is every tomato growers nightmare. Here’s my tips to control this devastating disease and prevent against it in the future.
The tell tale signs of tomato blight have hit us extra early this year.
It doesn’t normally show until the fruit are a good size, so we can just remove the leaves and let the fruit ripen on the stem. However, this is the earliest I have ever known blight to rear its ugly head, and the plants are still too young to have fruits on yet.
What is Tomato Blight?
According to the Royal Horticultural Society “Potato and tomato blight is a disease caused by a fungus-like organism which spreads rapidly in the foliage and tubers or fruit of potatoes and tomatoes in wet weather, causing collapse and decay.”
In my experience, it normally appears on the lowest leaves of tomato plants first, as a brown withering of the leaf. If left to its own devices, it will travel up the plant killing all the leaves (remember the importance of leaves in photosynthesis?) and eventually rots any tomatoes on the plant.
How Does It Spread?
The microscopic spores from an infected plant get blown on the wind (from other gardens & growers) which on their own are pretty benign. However, throw into the equation the correct environmental conditions – warmth and wetness (ie the past 5 British summers) and the spores begin their deadly march through the tomato & potato patch.
Interestingly, the spores can also over-winter in infected potato tubers in your soil so another good reason to have a good clear up at the end of the growing season.
Personally, I choose not to spray chemicals on my food plants, but I believe there are sprays you an buy to halt or stop an infection. I have also heard that a mixture of milk & water sprayed onto leaves will help/halt/prevent an infection. I’ll be trialling this during the summer and let you know how I get on.
Here’s my plan of attack.
1/ Moisture
To keep the leaves of our plants dry when watering them, I sank small plant pots into the ground next to the plants. Rather than splashing water all over the leaves and stalk (and activating those spores) with the hose pipe, the water now goes directly to the roots instead.
2/ Ventilation
A lack of planning at the start of our growing year meant that some of our plants were crowded by other plants. I removed these tomato plants (burning them just in case they were already infected)
I also removed the lower leaves from all the tomato plants that were touching the soil creating an overall drier and more ventilated environment.
As a poly tunnel gets very warm and moist when the doors are closed, the doors are left open overnight when it’s not too cold or windy.
3/ Disease Control
Once you already have an infection, you’ll need to be careful in how you deal with the infected parts as everything they touch (including your hands) creates a possible reinfection.
We now have a ‘blight bucket’ which all the diseased parts go into before being emptied into a dustbin and burnt.
4/ Successional Planting
As the very young plants don’t seem to get infected, I read somewhere that staggering the planting of tomatoes throughout the season can work as the late summer is usually drier than early summer. Not sure this applies to Cornwall but I’m staying on the positive side of positive as I LOVE our fresh tomatoes!
What have you found to work against the blasted blight?
Updated post here, written 2 months later.
Joss says
It has plagued us over the last few years this. But going back a little bit we had less trouble. This was partly due to a better summer, but also, I suspect to the fact that we had plants in pots that had far too much drainage – they were commercial pots with massive holes in the bottom. We had to water loads to keep up, but we simply did not get blight.
This year I have gone back to those pots, outside this is, but the rain is not doing them any favours, so not sure what the results would be.
HedgeComber says
Do let me know how you get on Joss x
Bridget says
I’ve heard that the milk and water works…it needs to be applied every 10 days. Horsetail spray is also said to keep all fungal diseases at bay.
Have received my print…love it! Beautiful card too.
Many thanks,
Bridget x.
Anne-Marie says
Hi there .. I found your site from Bridget’s site …and love your artwork. Great idea on watering tomatoes, and potatoes. I’ll do that in my garden!
HedgeComber says
Hi Anne-Marie, how lovely to meet you! Thanks for popping by and saying hello, Janie x
HedgeComber says
Hi Bridget :) Glad you got it OK!
I’ve taken drastic action in the poly tunnel this weekend, and taken ALL lower leaves off every plant! Poor things look a bit straggly but hopefully it will protect them. Haven’t heard of Horsetail spray, will go look into it. Janie xx
colouritgreen says
bum.
all round this year is looking pants veg wise.
Lance says
Hi Hedge Comber,
Just found your blog re. Tomato blight.
We suffered blight for the first time in 2012, and lost all our 24 tomato plants grown outside. Our charity kitchen garden is in Wapping, east London. Relentless rain and over intensive planting did for last year’s outdoor crop. My question is this, do you think that the support stakes used for that doomed crop might still carry spores? They have been stored outside over the winter. Maybe Jayes fluid would work? Any thoughts… ?
Jane Sarchet says
Yep, and it will be in the ground. And the air. Aren’t I a ray of sunshine!
Gutted for you that you lost all your plants, that sucks.
Your biggest problem in the rain. If you have a well ventilated greenhouse/polytunnel/glass or clear plastic covered area, you will still get the spores, but you’ll be able to keep the plants dry. That’s the important bit. The blight spores can’t cause havoc on a dry leaf or stem, as they are activated by water.
Hope that helps, please let me know how you get on this year
Janie x
Olunga Wanjala says
Just uprooted 40 tomato plants. Have de suckered all the leaves touching the ground what a shame could not have done it earlier …
Will share the status on course correction in the next couple of days.
Jane Sarchet says
Fingers crossed, and do let us know.
Janie x
Va. grower says
question? will a straw bed ,Keep down blight?
Jane Sarchet says
Not sure it would have any influence either way Va. If the spores are present, they are triggered by water/damp from above. Please let me know if you find out anything different though.
Janie x
Anna Mae says
Hello! Great article! We have tomatoes in a polytunnel, two varieties, an heirloom and a hybrid. We made the beginner mistake of planting in soil that had had blighted potatoes in it last year. I pulled up volunteer potatoes but to no avail- it would seem we have early blight- at least, I’ve seen a couple of patches with concentric rings in the dry brown, so that’s my guess. We also have a decent load of mostly green fruit that so far appear unaffected. I see you mentioned removing the leaves to let the fruit ripen on the stem…. I would be so grateful if you see this and could tell us more! If the fruit is still green does this work? Do you remove all foliage?
Jane Sarchet says
Morning Anna Mae, good to meet you :)
Start with all the affected foliage, which will be the lower branches. Remove them all and burn them (also clean your secateurs/scissors/gloves too as the spores will live on them). When you’ve removed all teh bad stuff, see what you have left. If there are no leaves left at all then the plant will die so you can leave the fruit on the plant and cross your fingers that some of it ripens or take it off the vine and leave on a sunny window sill – pop a couple of bananas with it as they speed up ripening in fruits & veg.
If you still have some leaves left the plant will probably survive, just keep watering and keep the leaves as dry as possible.
Good luck & do let me know you get on!
Janie x
Anna Mae says
Brilliant thank you, that’s very helpful! I will report back :-) How are yours this year?
Jane Sarchet says
All good so far, I have had some marked leaves but whip them off quickly now :)
Janie x