It’s not blight! (but it is blossom end rot)

As the title of this post suggests, my tomatoes do not have blight (yet!) This is something that I am extremely thankful for. Blight is a horrible disease that will easily wipe out an entire crop of tomato plants, leaving you with nothing other than a feeling of defeat and frustration.

I had not intended to write a post about blossom end rot, in fact, the thought did not even cross my mind until today. What prompted me to create this post is that I am a member of a few gardening forums on other social media platforms and over the last few days, I have seen an increasing number of people posting pictures of tomatoes suffering from blossom end rot, asking what is wrong and how they can fix the problem.

The gardening forums are friendly groups and many people will chip in to offer help and advice. Unfortunately, one common comment I see when these blossom end rot pictures are posted is people incorrectly advising posters that their tomatoes have blight and that the plants need to be pulled up and burned.

I know that people are just trying to help, but seeing people being told to burn their otherwise healthy, cared for plants makes me want to scream “No, no, no!” at the computer screen. The trouble is, blight is such a feared disease (for good reason) and has so much more publicity than other tomato problems, that people often mistake a little bit of blossom end rot – which is perfectly treatable, for something a lot more sinister. Plants which have a couple of fruit suffering from blossom end rot certainly do not need to be destroyed and with a little bit of t.l.c. you can probably avoid any further fruit on the plant from being affected by it.

Blossom end rot is a problem that is essentially caused by a lack of calcium in the plant. This is nearly always due to inadequate watering. It presents itself as little patches at the bottom of developing fruit, starting as slightly brown in colour and then spreading and rotting the fruit as the problem takes hold. This is one of my own “Black From Tula” fruits that succumbed to blossom end rot this week:

Blossom End Rot On Black From Tula Tomato

It is easy to see why some people may confuse this with blight, as blight will also rot tomatoes. The key thing to look at if you are unsure is the leaves of the plant. Blight will also kill the leaves – turning them brown / yellow / mottled, whereas with blossom end rot the leaves will be absolutely fine.

When it comes to blossom end rot, some people recommend treating affected plants with a solution of epsom salts, but in reality, this shouldn’t really be necessary. Almost all growing mediums should contain enough calcium already – it doesn’t matter if you are growing direct in the ground, in raised beds or in containers, the calcium will be there. What causes the problem is the plants ability to take this calcium up to the fruit, where it needs it.

This, I expect, is why there have been so many more posts from people affected by blossom end rot in the last couple of weeks. This heatwave has been something of a weather phenomenon. In my area of the UK we haven’t seen rain since early May and plants are definitely suffering. Prolonged hot, dry spells will lead to an increase in blossom end rot. Conversely, blight is actually kept at bay by dry weather like this, so that is one upside to the recent weather conditions!

You see, the issue with calcium and blossom end rot is not that the calcium isn’t present in the soil, it is that the plant is not absorbing the calcium and transporting it to where it needs to be in the plant. This is where you need to act! By keeping your plants regularly watered you will be ensuring they can take up the calcium in the soil and disperse it around the plant. In this weather, this may mean watering twice a day – if not more often. If you allow the plant to dry out you are giving blossom end rot a chance to thrive. Keep the soil moist and regularly check the developing fruit for any signs of rotting at the base. You may find that the fruits at the top of the plant are the first to be affected by blossom end rot. This is not unusual as they are furthest away from the nutrient source (ie the soil/plant roots). Tomatoes lower down the plant may be taking up all the available nutrients before the plant has a chance to spread them to the fruits at the top.

I have to be honest and admit that this weather caught me off guard and of my 12 tomato plants, 2 have developed slight cases of blossom end rot. My heritage tomato plant “Black From Tula” had two affected fruit and my “San Marzano” had 3 affected fruit. Once you find an infected fruit, you will need to remove it from the plant. While we can prevent other fruits from becoming infected, we cannot cure a fruit that has already been infected. This is one of my infected San Marzano’s:

Blossom End Rot

As nasty as this looks, it is important to highlight that this fruit was plucked from the vine nearly a week ago. I am sure there are people who would have told me I had blight and told me to destroy my plant. If I were a novice tomato grower and hadn’t known what I was dealing with, I may have listened to this incorrect advice. If I had done so, then I wouldn’t have still had this (now) perfectly healthy plant and all these gorgeous (and blossom end rot free) tomatoes:

San Marzano

My tomato plants are now healthy again and touch wood, there is now no sign of any blossom end rot on any of my fruits. All I did to cure the blossom end rot problem was adjust my watering technique. I was watering once a day and I must admit, there were a couple of days where I completely forgot to water at all. Now, I am watering twice a day, once in the morning and once in the evening. The tomatoes have perked up considerably and are doing well again. I have not given them epsom salts, extra feed or anything else whatsoever, all they have been treated to is more regular watering.

I know that simply adjusting watering may seem almost too easy to be a real “cure”, but the proof is in the pictures! Tomatoes are needy plants and if there is something they aren’t 100% happy with, you can be sure they will let you know one way or another! I am just hoping that this guide may help save a few tomato plants across the country from being needlessly uprooted and burned due to misdiagnosis. After all, blight is far too common for my liking, let’s not start killing off healthy plants too!


2 Comments Add yours

  1. carolee says:

    Very well said.


  2. Denise Machon says:

    Really useful and interesting article, thank you!


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