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.
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.
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.