What causes tomato stem rot?

What causes tomato stem rot?

Tomato stem rot is caused by bacteria species called Pectobacterium carotovorum or by Erwinia carotovora subsp. It is usually found on trellised/staked tomatoes because of the stems incurring damage due to being rubbed on ties or stakes. Tomatoes that have been pruned also have this. The bacteria that cause the stem rot usually infects plants only that have been damaged. 

This is because it spreads through cuts and abrasions. Bacterial stem rot affects nightshade vegetables only. Stem rot, u fungal disease also affects a wide variety of edible and ornamental plants. Here’s a wider explanation about this below.

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The disease can also be transmitted when you use seeds that are infected by the disease. Therefore, ensure that the seeds used are healthy and not diseased. Rain and mind can also accelerate the spread of this disease. 

One common type of tomato stem rot is known as timber rot or white mold. This is an excellent survivor in soils and it can stay for up to ten years. The disease mostly affects plants in climates that are cold and wet. It can also affect other plants include pepper as well as potatoes. This disease is called by a fungus called sclerotinia sclerotiorum.

 It can also affect weeds. The first sign can be soft rots on the stems, you may also notice some areas that are bleached on the stem.  Other signs include fuzzy mods that can be found on the inside or on the outside, they can also appear on the leaves, the leaves as well as on the stems.

You can prevent this problem by suing many strategies including practicing sanitation or using some cultural factors. In sanitation you ensure that you keep all your tools clean and cultural methods include practicing crop rotation and more. 

Symptoms of tomato stem rot

Lumps and outgrowths seen on the stem, most of the time usually near the bottom. If you see there is no need for panic as these are likely to be root initials that are kind of harmless. It has to be noted that tomatoes usually produce roots from their stem in a very simple way and one shouldn’t be concerned about this.

Another symptom is dead and rotten patches on the stems which shows that this is a disease called Didymella stem rot that is usually caused by a fungus called Didymella lycopersici. This disease can attack the tomato stems which leads to rotten and brown patches, usually, at any height, the stem base is what is mostly affected. 

Those plants that are affected with this disease can wilt and die which is a total loss. To prevent further spread, those affected plants ought to be removed as soon as possible to prevent the remaining plants from being affected too. 

Another symptom is brown patches on the stems which is a sign the tomato plant in addition has tomato blight which causes decay and brown patches on both the leaves and the stems. Another symptom is wilting with staining inside the stem which is usually caused by the diseases called fusarium wilt and verticillium wilt.

White mold or fluffy grey on the stems is another symptom that is caused by grey mold or sclerotinia which is also known as Botrytis cinerea. Just to add further to this, wilting of the whole plant is mostly noticed on the tomato plant when the first lot of the fruit is ripe and hence when it is ready to harvest. 

The Centre of the stem disintegrating is what causes the wilting. Pith necrosis is similar to this disease if you look at it closely. The only difference is that with pith necrosis, the outside of the stem in turn also becomes wet and slimy on a condition that the tomato plant is infected with stem rot. Plant extremities may reach to the extent of turning black and drop off, this might be a severe case.

Biology perspective

Looking at the stems you will see root initials which are as a result of humid conditions. When plants are under stress it usually leads to root formation on the stems mostly. Hormone weed killer contamination also plays a part as it promotes the formation of stem root. Further effects of the contamination on the foliage are usually noticed first as they are more dramatic and easily seen.

Treatment and control

In terms of an effective treatment and control, it has not been identified yet but if you notice the problem early the better. You can save the other plants from getting this disease by pruning off the affected areas. After that is done, make sure y disinfect the cut using an infusion of chives and garlic in water. 

In terms of prevention, having in mind that prevention is better than cure, you can do this by tying the plants loosely to stakes usually with soft ties to make sure they don’t rub on the stems. If you have chosen to prune the plants always make sure that your secateurs are disinfected between each cut. 

It has to be mentioned that those practicing their gardening in very humid climates usually in most cases grow bushy tomatoes, these people may wish to do a pruning that is light to improve air circulation and, in most cases, pruning is necessary in plants that are adequately spaced. 

A solution of eucalyptus oil and a dilute bleach are also suitable. Look after the plants with a close eye and always make sure they are healthy. The plants need to be supplied with enough nutrients and water to prevent them from getting the disease easily in cases when they are pruned or staked or trellised to cause damage. 

The root initials might not be easily seen but they will surely show fine-tuning of cultivation, mostly watering methods may be of paramount importance. This disease and tomato blight can be prevented by keeping the foliage and the stems dry when watering. Furthermore, diseases that might affect tomato stems usually stay long in the soil. 

One might have other alternatives like changing the system of growing. Growing the tomato plants in grow-bags or in pots will also help in preventing this disease. Removing the affected tomato plants can also surely help. And furthermore, there are no soil sterilizers or fungicides in home gardeners.

The preventive measures and strategies

The following are some of the preventive measures that you can use in order to reduce the chances of your tomato plants being affected by tomato stem rot.

You need to ensure that the seeds that you have used are healthy and from sources that are well certified. This greatly reduced the chances of your tomato plants being affected by stem rot later on. You also need to make sure that you use varieties that are very resistant to stem rot rather than using the varieties that are not resistant to this disease.  

When growing plants in a greenhouse, you need to make sure that you have put enough space between your plants so that they are well ventilated and grow healthily. You should prune the lower leaves, Mae sure that they do not make contact with the soil because this can easily accelerate the chances of your plant getting the disease. 

You need to ensure that you keep the humidity and the temperature at a good level. The humidity should be at least below 90% and you need to make sure that the temperature is at least above 15 degrees.

Overhead irrigation is one of the main things that needs to be avoided to prevent this problem. You also need to ensure that the soil is well watered before watering them again. Crop rotation should also be practiced between three to five years

All the volunteer plants as well as the weeds should also be uprooted from your fields, the debris should be gotten rid of after you have harvested the tomatoes and they should be burned. 

You need to prevent excess moisture; you need to ensure that the soil is kept dry so that you reduce the chances of the fungus from germinating. You should also use good drainage systems. You can use a soaker hose to water the plants rather than using overhead methods of watering the plants.

The poles and all the tools need to be disinfected after you have used them in your fieldwork. This ensures that the tools do not infect the plants that are not affected. 


Tomato stem rot is a very common disease in tomato plants and it is caused by a fungus, this disease affects the stems of the tomato plant. It can also affect the leaves of the plant tat came into contact with soil. There are many strategies that one can use in order to prevent this disease from affecting the plants some of these include crop rotation, keeping the soil dry, pruning the eaves, growing the plants spaciously and many more. One can also disinfect the soil and all the tools that are used to prevent further spread of the disease. 

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