Root rot often brings about the dreaded death of plants you have grown fond of. We will show you how to correctly identify, prevent and combat root rot.

Root rot can kill beloved plants

Not only the term root rot, but also that of root killer is often used in connection with the diseased roots of our plants. Other synonyms for rotten roots are, for example, blackleg, root neck rot or root burn. All these names stand for the same phenomenon: our plant has problems at the base, which often scares us gardeners. From the crops in the garden to large trees, all growth can ultimately be affected and threatened by root rot. The root collar or the entire root system is often affected and often all that remains is a soft, putrid mass.

What is behind the rotting and dying roots of our cultures? Bacteria and fungi are usually the culprits that cause this rot on the plant roots. In the following, we will tell you the exact causes of rot, how you can recognize them and what you can do best to prevent root rot.

Causes of Root Rot

Root rot caused by fungi

Root fungi are pathogens that infect and damage the roots of plants. Above ground, root rot pathogens lead to wilting and chlorosis, i.e. lightening or yellowing of the leaves. The most common causes of root rot are different species of the classic fungus Pythium or the egg fungus Phytophthora, but many other fungi can also cause rot on plant roots. Other known pathogens are Rhizoctonia, Fusarium or Phoma. However, an exact diagnosis is usually difficult because the root system is underground and the above-ground parts often show symptoms late. Below we show you a list of common fungal diseases and how they manifest themselves:

Above ground root rot leads to chlorosis

Damping-off

  • Seedlings turn black at the base, rotten and fall over
  • Roots grow weaker and also becomelazy
  • Root bark peeling off
  • Plants wilt, turn yellow and rot
  • Mostly caused by fungi of the genus Pythium

Root Tan

  • Caused by the soil-borne fungus Thielaviopsis basicola, also called Chalara elegans
  • Also known as root rot or blackleg
  • Roots turn brown, dry rot and the root tips remain white
  • Leaves turn yellow, slack in growth but don't die
  • Common in cyclamen (Cyclamen), chrysanthemums (Chrysanthemum), pelargoniums (Pelargonium ), lettuce (Lactuca sativa), tomatoes (Solanum lycopersicum), legumes and elder (Sambucus ) on
  • In carrots (Daucus carota subsp. sativus), this fungus causes rot in storage - also called "black carrot rot". The fungus Chalaropsis thielavioides also occurs as a secondary infection with this carrot blight
Carrot black rot affects stored carrots

Fusarium

  • The pathogens enter the plants through the root tips or through wounds
  • They clog the pathways and form toxic substances
  • Trigger rots including onion basal rot and root rot in spinach (Spinacia) and onion (Allium cepa)

Brick Blight or Hard Rot

  • Caused among others by Alternaria species (in potatoes caused by Alternaria solani or Alternaria alternataearly blight and hard rot)
  • Brown-black spots on the leaves, the stem also turns brown
  • Dark, sunken spots form on the tubers and the potato tissue underneath discolours, hardens and dies

Root killer disease or black rot

  • Lets begin to rot from Rhizoctonia solani from the lower leaves
  • Emerging potatoes will stain the stems and the base may turn brown
  • A greyish-white coating forms at the base of the stalks of the potatoes, hence the name "white trouser"
  • The tubers are deformed, have spots and the tissue in the middle is dying ("dry core")

Pink Root Rot

  • Used by different Phoma speciestriggered
  • Roots turn light pink to purple-brown
  • Leaves change color and plants are easy to pull out of the ground
    • For example,
  • Phoma betae causes root blight in turnips (Beta) and can also trigger storage rot
Rotted roots can kill the plant

Aphanomyces Blight

  • In the case of legumes such as haricot beans (Phaseolus vulgaris) or peas (Pisum sativum), root rot or black radish occurs
  • Radish blight is caused by Aphanomyces raphani
  • Radish (Raphanus) turns blue-black from the outside inwards and rots
  • After an infection, bacteria or Rhizoctonia solani often penetrate

Bacterial root rot

Bacteria often join when blight occurs, but bacterial blights can also occur naturally in wet weather, such as the following species:

  • Erwiniaspecies
  • Pseudomonasspecies
  • Rhizomonasspecies
  • Xanthomonas Species

Infection of the roots with bacteria is often favored by waterlogging in the soil. Bacterial rots are therefore often simply referred to as wet rots or soft rots. Watery stains often develop on carrots, onions, and other underground parts of plants. Symptoms of wilting also appear and the plants begin to rot and mushy.

Blight as a cause of root rot

This root rot on potatoes is caused by Phytophthora infestans, but many fungi from the genus can cause root disease on our crops. This fungus is well known, as it was the cause of great famines in the 19th century. In potatoes (Solanum tuberosum), the stalks turn brown and spots appear on the leaves. The herb eventually dries up and the tubers sink and rot. In tomatoes (Solanum lycopersicum), the fungus causes late blight. If you want to know more about this fungus - Phytophthora infestans - you can find more information here.

Brown rot in tomatoes can be caused by fungi

Detect and diagnose root rot

Because there can be so many different root rot triggers, it is often difficult to identify the culprit. This is also commononly possible under the microscope or in the laboratory. However, typical signs of root rot are initially signs of wilting. Therefore, most of us water the plants even more, which then has exactly the opposite effect. Only when the plants have died and you take them out of the ground do you recognize the dead soft root material. Believe us, ornamental plants get watered to death far more often than they dry up.

In addition to wilting, discoloration and chlorosis often occur on the leaves. The roots also often discolor and rot. In the case of root crown rot, the root neck often constricts, rots and discolours. Affected plants can also be easily pulled out of the ground because the roots are damaged or already dead and no longer offer enough support. As a result of this root damage and the partially clogged ducts, the plants can no longer absorb their nutrients properly and then die.

Prevent and combat root rot

We have summarized the most important tips for preventing and combating root rot on your plants below:

Tip 1: Avoid waterlogging

In general, controlling the environment can counter rot. Moisture and moisture promote fungal infections, so you should avoid waterlogging and keep the soil or substrate loose and well aerated. The firmer and wetter the soil, the more likely root rot will occur.

waterlogging
Waterlogging in plants promotes fungal infections

Tip 2: Note cultural sequence

If you have root rot in your garden, you should definitely pay attention to your crop rotation next year. A specific pathogen often only grows on a specific crop or crop family. So make sure you have variety in the garden. If your potato is rotting, avoid putting potatoes in the spot the following year - it's best not to put nightshades (Solanaceae) there at all. You can prevent root rot with a varied crop rotation and loosening soil cultivation.

Tip 3: Be careful with cachepots

In the case of indoor plants, cachepots are very decorative, but they can also quickly drown your ornamental plants. It is easy to overlook the fact that there is still water in the pot and unfortunately drown your plants. In addition, the permanent moisture promotes the infestation with root rotPathogens.

Tip 4: Till the soil

In heavy garden soil, adding sandy material or compost will help. Organic material promotes the formation of humus and the ability to store water.

Tip 5: Prevention instead of control

The use of fungicides is often not helpful because these agents have difficulty reaching the fungi in the soil, but various plant strengtheners can be used to inhibit rot and promote he althy plant growth. Unfortunately, there is a lot that can be done to prevent root rot, but acutely it is usually too late. Therefore, pay attention to good soil conditions and crop rotation in your garden beds. With anti-rot agents you can prepare and protect your plants well.

Who pays attention to good soil conditions prevents root rot

Some extracts and teas can be used to prevent root rot, for example:

  • Chamomile Extract: For this anti-rot extract, take a handful of dried chamomile flowers (Matricaria chamomilla) and place them in 1 to 2 for a day liters of water on. The extract should be diluted 1:5 before use.
  • GarlicTea: Chop about 300g of garlic cloves and then blanch the garlic (Allium sativum) in 5 liters of hot water. Then let it steep for a day and dilute the tea in a ratio of 1:3. Dip the root ball of your plants in this tea before planting to prevent root diseases.
  • Horsetail Broth: Leave 10 liters of water and 1 kg of fresh horsetail (Equisetum) for a day and then boil for half an hour. Dilute this broth 1:5 and use against soil fungus.

If your seedlings hang their heads or even lie completely on the ground, so-called "damping-off" is probably to blame. You can find out how to prevent and combat this in our special article.

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Gardening Tips