What causes tomato leaves to turn a speckled yellow?

We grow tomatoes from seeds and take them outside on sunny days. Last week, after being out for a few hours, some leaves of the tomato plants turned a mottled yellow colour. 

This is probably caused by a fungus.

We live in the woods, so we cannot escape from moulds, spores and fungi. One of the diseases caused by these is the famous “powdery mildew”. In our case, courgette and other plants are always affected every year.

It is a disease that causes the leaves to turn white, as if they were covered with flour. When the leaves turn white, the plant cannot photosynthesise, which can lead to poor growth.

The only way to deal with it is to cut off the white powdery leaves, which in our case means removing almost all the leaves and giving up on the plants.

The fruit is safe to eat, even if it is affected by powdery mildew. My understanding is that we cannot get rid of this disease as long as we live here. At some point, we need to live with them; disease and fungus.

There are so many moulds and fungi flowing in the air that mushrooms can grow everywhere on the lawn . We just have to do what we can to prevent as much damage as possible.

Therefore, it was expected that the tomato leaves would turn yellow again.

All we can do is to remove the yellowed leaves as soon as possible after finding them. If you take the tomatoes outdoors, keep the distance between each other. Some areas of the garden are more susceptible to the fungus than others, so we have to know about our garden condition and where to put them.

If I don’t keep our plants outside, the risk of mould and fungus is reduced. Still, I prefer letting them be exposed directly to the sun.

When we grow vegetables or flowers from seed, we always grow them in the garage after they have sprouted because the garage is the warmest place in the house.

Usually, before we plant the seedlings in the ground, we do a process called ‘hardening off’.

We don’t plant the seedlings in the ground straight away, but gradually take them out of the house a week or so before planting. The time to leave them outside should get longer day by day. In this way, they will gradually get used to the outside environment such as temperature, wind or changing weather.

However, when I take the tomatoes out on a sunny day, it’s not just hardening them off. Because our garage is not a greenhouse after all, I think it’s difficult to grow strong plants if I always keep them in the garage.

Last year we sowed and grew tomatoes in the garage. I kept them in the garage until hardening off and all of the vegetables and flowers became tall and thin.

Our garage has a semi-transparent roof, so it gets sunshine during the day and is relatively warm at night. However, because of the high ceiling and the translucent roof, there is not enough sunlight for the vegetables.

Both the vegetables and the flowers try to stretch themselves out in the sun and the seedlings grow long and thin. It was not a critical problem. The vegetables still grew well after transplanting on the ground, but it seems that they couldn’t stop themselves from growing taller even outside and they ended up being too tall for us to harvest…

After this experience, I decided to get them outside as early as possible when it’s warm and sunny.

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