Tomato diseases

Your tomato plants have grown up and are finally starting to produce the most beautiful tomatoes in the whole world (nothing less!), unfortunately a strange evil suddenly attacks them.

What is that? What did I do wrong? and above all, how do I get out of it? This multitude of questions can finally be answered thanks to this list of the main diseases and pests attacking tomatoes and their solutions :)

1- Apical necrosis or the famous black ass

black ass tomato

Your tomatoes are developing normally, but a spot begins to form at the base of them just as they are ready to ripen. This affected area is soft and brown at first, but quickly becomes hard, dry and black. It is good to know that by removing this part you can still eat the fruit.

The culprit: Your plants are most likely lacking in calcium to develop fruit well. But be careful, this lack is usually not because there is a lack of calcium in your soil. It is much more often caused by the lack of calcium available at the time of forming the fruit because there was not enough water to bring it to the fruit. In other words, it is very likely that your plant ran out of water at the critical stage of tomato development.

The remedy: The remedy is therefore easy to apply. Start watering your plants regularly to ensure that the plant has access to all the nutrients it needs at all times and do not stir the soil around your plants too much to avoid cutting roots unintentionally. Pay particular attention to growing in containers, which increases the risk of drought for your tomato plants.

On the other hand, if your watering is constant you can check the pH of your soil to make sure that it is between 6 and 7 (fairly neutral) so the tomato will be able to assimilate the calcium therein. You must also be careful not to use a fertilizer that is too rich in nitrogen (indicated by the first number 15-10-10) which would cause the plant to grow too quickly, which will then use the minerals for the foliage and not the fruits.

Finally, it is good to know that certain varieties of tomatoes are more sensitive to it than others.

apical necrosis

Photo credit: Ontario Ministry of Agriculture, Food and Rural Affairs

2- Mildew


Photo credit: Garden Relaxation

Towards the end of summer, the lower leaves of your plants begin to have small brown spots that circle around like a target. Then the whole leaf turns yellow and brown and finally falls off. The fungus progresses up the plant fairly quickly, often turning the stem brown as well. The fruits, on the other hand, just before ripening develop soft brown/black depressions. They are unfortunately no longer suitable for consumption.

The culprit: Downy mildew, a naturally occurring mold ( Alternaria solani ) in soil that thrives when the winning conditions are present.

The remedy: Prevention is key here. It is necessary to avoid the conditions where the fungus begins to develop, i.e. persistent humidity on the leaves of the plant. So plant your plants at a minimum distance of 50 cm between them to ensure good air circulation so the leaves can dry completely between waterings or rains. Also, when you water, only water the ground avoiding the foliage. Finally, remember to rotate crops from one year to another or not to plant tomatoes always in the same place in your garden.

If your plants are affected, quickly remove what is diseased and apply a fungicide.


Photo credit: Smart Gardener

3- Burst fruit

Your tomatoes burst in the top next to the clip. Often insects (eg ants or earwigs) attracted by the juices of the fruit will lodge there.

The culprit: Again the culprit is water. A period of drought followed by a period of abundant water will cause the tomatoes to grow too quickly and may then burst.

The remedy: The secret is consistency in watering. It is better to water regularly rather than once in a while in large quantities.


Photo credit: Garden and Vegetable garden

The sphinx caterpillar

Your plants were magnificent yesterday, but in one night the leaves and fruits were devoured? It was probably this caterpillar that had a feast during the night.

The culprit: The tomato hornworm ( Manduca quinquemaculata) which can measure up to 10 cm and is a beautiful green tomato plant. These larvae are found in our tomato plants because this is where the mother comes to lay her eggs directly in the pantry for her little babies.

The remedy: Fortunately, there is usually only one caterpillar per plant, rarely 2. It must then be found and eliminated. Take the time to observe your plant well, it has a perfect camouflage :)

Finally, with all these solutions to pamper your plants, we wish you a wonderful tomato harvest!

sphinx caterpillar

Photo credit: Whitney Cranshaw, Colorado State University