Tomato leaf mold – cause and counteracting
Anyone who has cultivated greenhouse tomatoes is afraid of leaf mold. This is one of the most common and harmful fungal. Find out how to fight it and what to do to prevent it from appearing again.
Brown leaf spot (mold) is a fungal disease. It is caused by the insidious fungus Cladosporium fulvum, which can winter for years in the ground and even on structural elements in a foil tunnel. The disease develops on the leaves, but affects the entire plant. It can take over the entire plantation in no time.
The first symptoms appear on the lower leaves. Initially, yellow spots appear on them, which means that the disease can be confused with other diseases – yellowing of tomato leaves can be a symptom of many diseases. The spots are about 1 cm in diameter, not more.
Over time, they start to enlarge and darken until they turn brown, hence the name brown / brown spot. You can see a grayish bloom on the underside of the leaf – these are fungal spores that spread to other plants.
The leaves die and shrivel up, then the same happens with the flower stems and sepals. The fruits, as a rule, do not look worse, but on the infected plant they stop growing and rarely ripen.
The harmfulness of leaf mold
As soon as you notice that the tomato leaves are slightly yellow, check for the remaining symptoms. Brown spot is a really serious disease. Its development in the foil tunnel may mean that you will have a problem with it for several years.
The browning, and before that, the yellowing of the leaves of tomatoes is not a problem in itself. Worse, because of this, photosynthesis stops to a large extent.
And that is a problem for the whole plant. If brown blotch appears early on the leaves and also stings the flowers, the tomatoes will not set. If it appears when the fruit is young and green, it won’t let them ripen.
This is a huge loss for commercial crops, but it is also a pain for gardeners. It must not be forgotten that tomato leaf diseases can spread to other plants, both cultivated and ornamental.
The reasons for the appearance of leaf mold
Tomato leaf mold appears in the garden, but is rather preventable. Much more often it appears under foil and in greenhouse crops. There, the fungus Cladosporium fulvum has the best conditions for development. If it is more than 15 degrees warm and the humidity reaches 90%, the spores wake up and start occupying the plants.
Tomato leaf mold – how to fight
The fungus can hibernate in the substrate. It is resistant to frost and drought, it preserves well even for many months or years. Most often it hibernates in plant remains, also in the substrate.
It also often takes up construction elements – stakes, glass joining or ropes. It can occupy almost any place under the foil. Therefore, if you do not take the correct measures, the yellow leaves of the tomato will appear every year.
The leaf mold is very easy to spread around the garden and other crops. The spores spread on tools and even gloves. They can also wander with drops of water or gusts of wind to remote parts of the garden.
As soon as tomato leaf diseases appear, start combating them. It is a good idea to start by removing infected plants as soon as possible. In addition, tomatoes should also be sprayed with fungicides intended for plant protection.
Unfortunately, this means that it will not only be necessary to spray tomatoes, but also to disinfect all elements of the structure under the foil. Tools and pots should also be sprayed, for example by washing them with garden soap. Thanks to this, all these elements will be decontaminated. Gloves should be thrown away.
prevention
For all fungal diseases, including tomato leaf septoriosis and gray mold, prevention is the most important factor. And it is not only about regularly disinfecting the substrate or preventive spraying, but also preventing the fungi from developing. How to do it?
First of all, it is important to ventilate greenhouses and tunnels regularly in order to reduce the level of humidity there. What’s more, you should also be careful not to wet the tomato leaves when watering. The appropriate spacing of plants guarantees that they will be able to ventilate better.
It is also worth using crop rotation, after tomatoes they grow resistant plants. However, if the problem with brown leaf spot does not go away, choose only new varieties that are more resistant to the disease. There are many indications that cherry tomatoes are less likely to experience leaf blotch than standard tomatoes.
