Why Do Green Tomatoes Rot on The Vine?

Tomato season can be so satisfying. To pick all those juicy and tasty tomatoes and eat them fresh or cooked, or preserve them, is the best reward after all your time and hard work invested in your garden. But sometimes, gardening can be disappointing. Especially when you know you are so close to getting your reward, in this case, ripen tomatoes, but suddenly you see that the green tomatoes are starting to rot on the vine.

green tomatoes rot on the vine

There are more reasons why green tomatoes can rot on the vine.

Fungal diseases, such as early blight, late blight, or fusarium wilt can be the reason why green tomatoes rot on the vine, but they can also rot because of a result of pests or other bacterial diseases and cultural conditions.

Green tomatoes can rot on the vine because of blossom end rot as well, which is a very common condition caused by calcium deficiency.

In this article, I will talk about the reasons why do green tomatoes rot on the vine.

Early Blight

Early Blight is caused by the fungus Alternaria Solani and it is characterized by black and brown spots on the tomato stems, leaves, and fruits.

These spots usually form concentric circles and the surrounding area might become yellow.

Early Blight spreads from the bottom to the top of the plant, so, the spots first appear on the lower leaves.

The reasons why Early Blight can form on your tomatoes are humidity and not enough heat. Watering your plants from the top and wetting the leaves can also cause this problem.

Luckily, you can stop the disease to spread, but you have to be vigilant. As soon as you observe the spots, you must remove all the affected foliage.

If the disease gets into the tomato fruits, these will not be suitable to be consumed, and they will rot at the end.

To make sure that the disease is not spreading after the affected foliage is removed, spray a copper fungicide on your tomato plants and repeat the treatment every 7 to 10 days.

Late Blight

Late Blight is another disease that can cause your green tomatoes’ rotting.

It is caused by the fungus Phytophthora Infestans. This can not only affect your tomatoes but your potatoes and other vegetables as well.

Unfortunately, this disease cannot be cured, and it can be very damaging because it spreads rapidly.

Late Blight can kill your affected tomato plants within days.late blight

This disease appears and spreads quickly mostly in humid and warm weather.

This fungal disease appears as irregular, grayish-green, purple, or dark brown lesions on the stems and leaves. Then this spreads quickly to the tomato fruits that develop brown and black lesions.

The spots, sometimes can have whitish mold that contains the fungal spores. Usually, these moldy spots are forming on the underside of the infected leaves.

When Late Blight appears on your tomato plants, destroy the affected plants and remove the debris from your garden. Do not put these in the compost, because the fungus can be spread to the new plants the next year.

Fusarium Wilt

Fusarium Wilt is a fungal disease as well, that will cause your tomatoes to wilt and the fruits to rot.

It is caused by the fungus Fusarium oxysporum, which can be found in the soil. If you think the soil you are using for tomatoes could be infected with this fungus, you should solarize it or plant tomato varieties that are resistant to fusarium wilt. On the package, you should see this marked with “F”.

Solarizing the soil means that you raise the temperature of the soil before using it. This way, you can kill the fungus spores.

Fusarium Wilt usually appears on one side of the plant. The foliage starts to turn its color from green to yellow, then this may spread to the whole plant.

When you cut open the infected stem you can see brown streaks. This means that the disease blocks the transport of water and nutrients to be transferred from the roots to the foliage and fruits.

green tomato rot on the vine - blossom end rot

Blossom End Rot

Blossom End Rot is the most common reason why green tomatoes rot on the vine. This starts with a small black spot that starts from the blossom end of the fruit and then spreads on the whole fruit.

Luckily, Blossom End Rot is not a disease. More like a condition that is caused by a low level of calcium and water in the plant.

Blossom End Rot can form because of irregular watering and fertilizing, the weather conditions, or the quality of the soil.

This can be easily prevented by fertilizing regularly and consistent watering. When planting the tomato plants, make sure you are using quality soil that is well-draining but doesn’t dry out too fast.

Wrap Up

Watching your green tomatoes rotting on the vine is so disappointing!

Fungal diseases (Early Blight, Late Blight, or Fusarium Wilt) can be one of the reasons why your tomatoes are rotting on the vine before ripening.

These diseases can be prevented if you water properly and you keep your tomato plants nice and clean. Prune them if they need it, so the air can flow between the leaves and foliage and keep clean and weed-free the area of your tomato plants.

Fertilizing regularly can prevent Blossom End Rot, which can be another reason for rotting tomatoes.

Please remember: don’t put diseased tomato plants in your compost. The fungus can spread to the new plants through the compost. The best is to burn them or if that is not possible, just remove them from your garden.



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