What Causes Calla Lily Root Rot? (Research Based)

Root rot is a kind of plant problem that creates serious damage to the plant even before it gets noticed. Even though the signs and symptoms are shown only after the damage is done to the roots, there is always a possibility to save the plant by taking action immediately. 

This article walks you through everything you need to know regarding calla lily root rot. These include the causes, telltale signs, and possible solutions to save the plant. 

If you are short on time, here’s a synopsis of what we’re covering in detail.

The number one cause of calla lily root rot is overwatering and its associated problems. Check for symptoms like rotten smells, leaf deformations, and dark mushy roots if you suspect root rot. If these signs are present, repot the plant in a new pot and soil mixture to save the plant from further damage.

Now, let’s dive deeper into much-needed details.

Signs Of Calla Lily Root Rot

The well-known signs of calla lily root rot are dark mushy leaves and leaf deformations like yellowing, curling, drooping, browning, and drying. However, there are a couple more signs like the rotten egg smell, the presence of fungi in the soil, etc which also suggest the chance of root rot.

Assessing the signs is where things get tricky. Not all symptoms are shown by every calla lily plant. Nevertheless, even if only one sign is shown by your calla lily plant, it proves that your plant is in distress in one way or other.

Let’s go deeper into each of these signs so that you can analyze your plant and take a decision on what to do forward real quick.

1. Rotten Egg Smell

This is by far the first symptom to check for if you suspect root rot in calla lily. 

Calla lily root rot is nothing but the roots of the plant decomposing or decaying for a variety of reasons. Furthermore, fundamental biology dictates that a foul odor develops whenever something decomposes. And, that’s how we arrive at this sign.

The best and most straightforward way to check for a rotten odor is to smell the base of your calla lily plant near its roots.

For those of you who use organic matter as fertilizer, then it gets tricky to identify calla lily root rot in this way. Because most organic materials have a similar rotten smell, you might not be able to tell one from another while using organic fertilizers.

2. Presence Of Fungi

If you notice any white, bubbly substance on the top layer of the potting soil, there is a good likelihood that your calla lily has a fungal infection that may have already resulted in root rot.

Numerous fungi, particularly Armillaria mellea, Clitocybe tabescens, and Fusarium, as well as various oomycetes, such as Pythium, Phytophthora, and Aphanomyces, are responsible for root rot in many plants.

3. Unhealthy leaves

Whenever a plant is under stress, leaves are the first ones to show symptoms. Just like how eyes are for humans.

For the sake of simplicity, all the leaf symptoms are classified under this section. They include yellowing, browning, curling, drooping, and drying. 

Your calla lily plant’s roots lose the capacity to draw water, air, and other vital nutrients from the soil when they have root rot. This causes the leaves to curl inward and conserve water. 

The plant cells in these leaves begin to die if the condition doesn’t get better over time. As a result, leaves begin to change color. The usual color transition is from green to yellow, then to brown. However, under severe root rot, these leaves just straight away wilt and dry from their wrinkled state without changing colors.

4. Dark Mushy Roots 

With the help of symptoms shown above the soil, till now we were simply guessing whether the plant has root rot or not. If you find a couple of those symptoms, then it’s time to assess the roots of your calla lily plant to make 100% sure whether it has root rot or not.

We don’t recommend uprooting the plant completely. Instead, scrap ¾ portions of potting soil from the soil using your hand slowly without damaging the roots.

And while doing it, if you notice very weak roots that have a mushy appearance, then there is a high chance that your plant has root rot. Additionally, rotten roots will be very brittle. Just by your touch, it will break from the root bulb.

Causes Of Calla Lily Root Rot

The number one cause of calla lily root rot is overwatering. These plants have moderate water requirements, however, if the roots are always sitting in water they will rot in a matter of time. Some other problems like bacterial & fungal infection, poor drainage and pot, overfertilization, and temperature stress also trigger root rot in calla lilies.

Even though all these causes seem to be different, they all are associated with each other. You will get to know more clearly when we get into the details of each of these causes.

1. Overwatering

Maybe you know already, but I’ll reiterate it. Overwatering is by far the number one cause of calla lily root rot.

Calla lily plants love water, but that doesn’t mean you can simply keep the root ball drenched in water all the time. The roots standing in water will lose the ability to breathe and starts to rot and die resulting in root rot, as simple as that.

Preventive Measure: Set up a watering schedule based on the climatic conditions in your region. Eg: Water daily in hot and humid climates, whereas twice or thrice a week in moderate conditions.

2. Bacterial & Fungal Infection

Bacterial and fungal infection is closely related to overwatering. It is scientifically proven that overwatered soil is a breeding ground for bacteria and fungi. 

The commonly seen root rot-causing fungi include Armillaria mellea, Clitocybe tabescens, and Fusarium. With the use of a variety of different enzymes, these fungi kill the plant root by destroying its supportive tissues.

Preventive Measure: Most of the time bacterial and fungal infection is spread through the contaminated water. So it is recommended to use either RO purified water or sedimented water that has been kept stable for more than 24 hours.

3. Poor Soil, Pot & Drainage

If you are not overwatering and there are no visible bacterial or fungal growth in the soil, then the next possible cause for calla lily root rot is poor soil or bad pot without adequate drainage capability.

No one will dispute the fact that everyone periodically overwaters their plants. 

And the presence of a soil mixture tailored specifically for calla lily plants is helpful in those rare cases of overwatering to drain the excess water. However, when you have a bad soil mixture like a cloggy or damp one, it will not drain the excess water and may cause root rot.

The same can be said for pot material as well.

Preventive Measure: Ideal way to prevent calla lily root rot caused by poor soil and drainage is by using a perfect potting soil mixture specifically made for calla lily plants. Also, earthen ports like terracotta are recommended over fancy metal or plastic pots.

4. Overfeeding

Similar to how overwatering is causing root rot in your calla lily plant, overfeeding (aka overfertilization) can also cause the same in the long run.

As mentioned in the Penn State extension overfertilization leads to too much salt buildup in the soil. These salts harm roots by decreasing the net flow of water into the roots and by unintentionally increasing the risk of root infections and damping-off in plants.

Preventive Measure: To prevent overfeeding, do not apply too much fertilizer to your calla lily plant in short intervals. It’s as simple as that. It is recommended not to fertilize more than twice a month during the blooming season and reduce it to once a month or once in two months during off-seasons.

How To Save Calla Lily From Root Rot?

Repot the calla lily plant as soon as you suspect it has root rot. To enhance the health of existing roots during repotting, it is advised to treat the roots with a fungicide and hydrogen peroxide solution. Make sure to water your plants only after the top two inches of soil are dry after repotting.

While repotting, make sure that you use a brand-new container with new soil to prevent any cross-contamination.

Before starting the repotting process, make sure that you got all the necessary items handy. Those include,

• New pot & fresh potting soil
• Rooting hormone
• Sterilized scissors
• Hydrogen peroxide
• Fungicide
• Sink with running water

Once everything is ready, you can follow the step-by-step process to repot your calla lily plant.

1. Remove the calla lily plant from its current pot gradually without harming the stem or root. Do not apply force, because these plants have a delicate stems which might get cut from the root very easily.
2. After completely removing the plant, wash the roots in running water to eliminate the existing potting soil. Ensure that all of the current soil has been removed.
3. Find any damaged roots by looking at the roots. Dark brown or black will be present on damaged roots. Additionally, they appear mushy.
4. Remove all of the totally and partially damaged roots from the base using sterile scissors.
5. To the remaining roots, apply hydrogen peroxide solution and rooting hormone.
6. Apply fungicide to the new pot and add potting soil to the bottom 1/4 of the pot.
7. The calla lily plant should be placed inside before adding more potting mixture. To effectively water and fertilize the plant, leave at least 3 to 4 inches at the top.

Water the calla lily plant well once repotting is complete to help the soil and roots bind together. The roots will bind in the new soil over the course of at least two weeks. 

Make sure you never overwater the plant again after it has recovered. Also, keep the plant in a bright area so that even if you overwater slightly, it will be negated by light and temperature.

Sources

To back up the information we provide in our articles, the Plantials team only uses high-quality sources published in peer-reviewed university or scientific research journals.

1. An Investigation Of Rhizoctonia Root-Rot Of Calla Lily In Relation To Chemical Manuring, Uae Journal Of Phytopathology.
2. First Report Of Root Rot Caused By Fusarium Solani On Calla Lily In India, The American Phytopathological Society (Aps) Publications.
3. Identification, Detection, And Quantification Of Pythium Species Causing Root Rot Of Calla Lily In California, Usda Agricultural Research Service.
4. First Report Of Pythium Root Rot Of Calla Lily (Zantedeschia Rehmannii) Caused By Pythium Myriotylum In Japan, Via Cab Direct.
5. Root Rot Diseases In Plants: A Review Of Common Causal Agents And Management Strategies, Agricultural Research & Technology Open Access Journal.
6. Over-Fertilization Of Potted Plants, Penn State Extension.