Cause Of Root Rot: Root Rot Remedy For Garden Plants, Trees, And Shrubs

Cause Of Root Rot: Root Rot Remedy For Garden Plants, Trees, And Shrubs

By: Jackie Carroll

While many people have both heard of and dealt with root rot in houseplants, most are not aware that this disease can also have an adverse effect on garden plants outdoors, including shrubs and trees. Learning more about the cause of root rot and how to look for early signs of root rot in garden plants will go a long way in its treatment. For root rot prevention and treatment info, keep reading.

What is Root Rot?

Root rot is a disease that attacks the roots of plants growing in wet soil. Since the disease spreads through the soil, the only root rot remedy for garden plants is often to remove and destroy the plant. However, you can try these corrective measures if you want to attempt to save a particularly valuable plant:

  • Keep the soil as dry as possible.
  • Don’t irrigate the plant unless the soil is almost completely dry.
  • Pull back the soil to allow moisture to evaporate from the soil.

The cause of root rot is a fungus. Species of the Pythium, Phytophthora, Rhizoctonia, or Fusarium fungi are the usual culprits. These fungi thrive in wet soil, and you can transfer them from one part of the garden to another when you transplant ailing plants.

Identifying Root Rot

When it comes to identifying root rot, look at the plants. Plants with root rot can’t absorb moisture and nourishment from the soil properly. The plants often resemble those suffering from drought and stress and mineral deficiencies.

Signs of root rot in garden plants include stunting, wilting and discolored leaves. Foliage and shoots die back and the entire plant soon dies. If you pull up a plant with root rot, you will see that the roots are brown and soft instead of firm and white.

Trees with root rot develop cankers, ooze reddish or black sap, and sometimes develop dark vertical streaks.

Treatment for Root Rot

The best root rot remedy for garden plants is prevention. Prevent root rot by filling in low parts of the garden and improving the soil with organic matter so that it drains freely. If you can’t improve the drainage, use raised beds filled with well draining soil. Taking care not to overwater garden plants will also help.

There are chemical fungicides and biological agents labeled as treatment for root rot disease; however, you should not use these products unless you know which fungus is causing the problem. Contact your local agricultural extension agent for information about how to have the fungus identified.

Once you know which fungus you are treating, your agricultural extension agent can recommend a product to treat that specific fungus. Fungicides are toxic chemicals that should be used with caution. Read the label and follow the instructions exactly. Store them in their original container and out of the reach of children.

Even when all of the precautions are taken in the garden, root rot may still occasionally become an issue. However, if you pay attention to the signs of root rot in garden plants, you’ll have a better chance of saving your plants.

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How to Fight Stem and Root Rot

by Matt Gibson

So you may have overwatered your plants once or twice. Then you start to see the leaves getting dull, turning yellow, and looking rather sick. You take steps to correct the watering issue, but the plants don’t bounce back. Chances are, your garden is suffering from root and stem rot. These types of garden rot is caused by one of two issues. Either your plants got waterlogged due to overwatering or improper drainage or a fungus in the soil attacked and infected the roots.

If the crown or major roots are affected, your plants are in for some dark times, and without immediate help, they will wither away and die. There are some actions you can take to save them, but if the roots are too far gone, it’s best to discard, disinfect, take preventive measures against future attacks of fungal disease, and start again.

Not sure whether root and stem rot is the culprit? Smell the base of your plant around the root area. If it smells awful and moldy, it’s probably root rot. Remove the plant from the soil. Do the roots look white, firm, and healthy? Or are they brown and slimy? If they are brown and slimy, root rot is most likely the cause.

Symptoms of Root and Stem Rot

If you notice that your plants are slowly wilting and the leaves are turning yellow or dull for no known reason, your plants may be affected by root and stem rot. The wilting and dulling of color may happen quickly or over the course of several months.

Check the roots of one of the plants by removing it from the soil and feeling the roots with your hands. If the roots feel mushy and look dark instead of a creamy white or tan, you probably have root rot issues. Sometimes, infected roots will fall off when you touch them. Some healthy roots can be black or dark-colored, but they will still be firm to the touch, not mushy or limp. However, most healthy roots will be light-colored, which means that they are functioning well and are not suffocated by waterlogged soil with insufficient drainage.

Healthy roots have smaller feeder roots, or rootlets, which can be easily spotted when checking the root system. On plants affected by root rot, the feeder roots will no longer be attached. Usually, if the roots are affected by rot, the crown of the plant will also begin to turn brown or darken in color.

Treating Root and Stem Rot

In order to treat plants affected by root rot, swift action must be taken to save your crops. If you caught the problem early enough, there’s a good chance that you can address the issue and give your plants a fighting chance to bounce back. Remove the affected plants from the soil, and gently wash the roots under running water. Wash away as much soil as possible, and don’t worry about any affected roots that fall off in the process. Try and be as gentle with the plant as possible while you’re treating them, though.

Using a sharp, clean pair of gardening shears or scissors, cut away all of the remaining roots that are affected. This may involve removing the majority of the root system if the plant is severely impacted by rot. If so, reclean the scissors with rubbing alcohol after removing infected roots, and then trim back one-third to one-half of the leaves on the plant. Because the plant will not need to support as much top growth once it’s trimmed, it will have a better opportunity to regrow the root system and get back to good health.

Resume treatment by disposing of all the soil in the pot that the plant was in. If the plant was not in a pot, you may consider potting it now and treating the garden bed soil with a fungicide and/or solarization. After throwing out the soil from the pot, wash the pot thoroughly with a solution that is one part bleach and nine parts water. If you have fungicide on hand, dip the remaining roots in the fungicide to kill off any fungus that may be lingering around. Now that the root rot has been treated and the pot has been sanitized, repot the plant in fresh, clean potting mix.

Make sure that the plant’s new container has good drainage, and only water it when the top of the soil is dry as a bone. Allow the plant five to seven days to regrow its root system before adding any fertilizer, as it may shock or stress the recovering plant.

Control

There’s no getting around it: all badly affected plants need to be removed and destroyed. Only try to treat moderately affected plants. If you were planting in containers, the control process is a simple fix. Toss out all impacted soil, as you don’t want to risk recontamination. Thoroughly clean all containers with a bleach solution that is one part bleach and nine parts water. Don’t forget to clean any and all tools that you used during the process of decontamination, including your gloves and even shoes.

If you were gardening in the ground or in garden beds, control may be a bit more difficult and time-consuming process than you had hoped, but it’s not impossible. One method you may want to consider is a fungicide soil drench. This can be a costly process, and you will want to get help from a professional if this is something you want to look into. The recommended approach to prevent future problems is soil solarization.

Soil solarization is the process of covering your soil with a tarp so that it heats up to more than 125 degrees Fahrenheit, killing off any fungus and bacteria that the soil may be harboring. Not only does soil solarization kill fungus and bacteria, it also wipes out a wide range of other pests that can wreak havoc on your garden beds, including nematodes and noxious weed seed. Plus, heating up your soil using solarization also stimulates the release of nutrients from the organic matter that is present in the soil. So after the solarization process is complete, your garden beds will be ready to produce like never before.

First, till the top layer of the soil. Then, rake the top layer until the surface area is smooth and even. Because wet soil conducts heat more efficiently than dry soil, water the area you plan to solarize until it is damp—but not so overwatered that it becomes soggy, as too much water will keep the temperature from reaching the level needed to kill off the fungus. Once you have a garden full of tilled, level, damp soil, you’re ready to cover it with tarp.

If you live in a warm climate area, cover your garden beds in clear plastic tarp for four to six weeks during the summertime. Ideally, the top six inches of soil will reach temperatures of up to 125 degrees Fahrenheit. If you live in a cooler climate area, use a black tarp instead of a clear tarp, as black tarp will attract the sun’s rays and increase the temperature underneath. In cooler climates, you will also want to leave the tarp in place for eight to 10 weeks, giving it more time to kill off all the fungus, bacteria and pests in the soil.

Preventing Root and Stem Rot

The only true way to fight root and stem rot is prevention. The two main components that lead to rot are temperature and oxygen. Plants, like all living things, need to be able to breathe in order to function properly. If the roots can’t breathe, the plant can’t grow. Prevent this lack of oxygen by making sure that roots are planted deep beneath the soil and that the soil is packed in loosely enough to allow oxygenation. If you are using a hydroponic or aeroponic growing system, make sure your air pump and air stones are large enough to keep water bubbling to allow plentiful amounts of oxygen to reach the root systems.

Hot temperatures are another thing that can lead to mold and mildew infestation. Unfortunately for outdoor gardeners, there’s not a lot that you can do to change the weather, so if you live in a warm climate area, consider adding rocks underneath the soil to improve drainage, and add mulch on the top layer to cool off the soil underneath. Use cool water when hydrating your plants as well, as hot water and hot weather is a bad combo for mold and mildew. Indoor gardeners may simply want to turn up the air conditioning during the summer months and provide plants an environment with proper ventilation.

Root and stem rot is not an uncommon problem, nor is it the end of the world. However, now that the problem has been identified, it’s time to work on a solution. Treating, controlling, and preventing root rot can be an arduous process, but anything worthwhile takes a bit of blood, sweat, and tears. If root and stem rot have taken hold of your garden, don’t give up hope—take up arms. You are now equipped with all the weapons you need to win the fight against rot and take your garden back.


Root Rot Treatment

Symptoms of rot include yellowing, stunted growth, wilting, etc as shown on this tomato. Source: Jnzl

Treatment of these rots really depends on the variety of rot you’re dealing with.

For some of these rot types, there are potent fungicides that can be used to prevent further spread. These are usually applied directly to the soil and kill off fungus in the garden bed. Most are chemical methods, as there are very few organic fungicides that prevent issues in the potting media itself.

But even these chemical methods don’t work on all forms. For instance, our top three are all much more complex, and can often become a death sentence for your plants. Few anti-rot methods work on these, although a few very strong chemical methods may have limited effect.

What does seem to help in most cases is the application of beneficial mycorrhizae to your soil when planting. These mycorrhizae develop a symbiotic relationship with your plant, sharing space safely with it and helping protect it from outside damage while sharing the same food and water. Particularly good options include Bacillus subtilis, Trichoderma harzianum, or Gliocladium virens, all of which seem to repel the pathogens well. Adding these to your soil or applying them directly to the root system prior to planting can be very beneficial.

It’s also possible with smaller plants to trim off dead portions in an effort to protect the rest of the plant. For instance, if you find orchid roots rotting in their pot, you can carefully remove the plant, trim off the fungus and soft rot, and repot in fresh orchid media with excellent drainage.

What To Do If The Plant’s Already Dying

If your plant is already dying, there’s not a lot that you can do to prevent its decline. But you can still attempt to propagate from healthy cuttings and thus save the plant.

Select cuttings that are high up on the plant but still vigorous. Follow common methods for rooting your cuttings, and use sterile soil to do so. Don’t plant it in the same location as the prior plant was at, as it may also be at risk in that location until the fungus is gone.

If you’re not sure which type of rot’s set into the plant’s root system, consider taking the roots to your local garden extension and asking. It’s best to bag up the roots in a doubled zipper-sealed bag so that nothing on them can escape. The people at the extension office can generally provide insight into exactly what it is so you can try to prevent it in the future.

Dispose of your old plant without composting it, roots and all. You can consider solarizing the soil to kill off fungal pathogens, but remember that this will also kill off beneficial microorganisms in the ground too.


How to Prevent Root Rot

Once you have treated the root rot, it’s important to know exactly how to avoid it in the future. As you might have guessed from the symptoms and treatments above, it’s important not to over-water your monstera.

Your monstera only needs watering when the top two inches of soil are completely dry. If you water it when it is any wetter than this, then you run the risk of it developing root rot again.

Another good way of preventing root rot is to ensure your monstera plant is regularly positioned in direct sunlight. As you will likely know, sunlight is essential for keeping your plant healthy.

But keeping your monstera in direct sunlight, for at least part of the day, will help the soil to remain dry. But, make sure it doesn’t stay in the light for too long as an excessive amount of warmth can aggravate the causes of root rot.

As we have already mentioned, a pot with a good level of drainage is also important. This is true of all pots but especially those for monstera plants. Owning plants has become very common in recent years. So a standard sight in homeware shops are aesthetically pleasing plant pots and baskets.

But these are primarily designed for how they look, rather than how well they work. So, when you buy a new plant pot, make sure that it will be able to properly support and drain your plant and its soil.


How to Save an Overwatered Plant

If you find out at the beginning stage by understanding the initial symptoms, you’ll be able to save the plant just by cutting the water. Locate the plant to a dry spot and stop watering until you see the soil is dry to touch. Also, remove a bit of top growth, flowers, and fruits (if any), this will allow the plant to focus its energy on survival.

If your plant is affected seriously, apply these measures:

  • Move the plant to a spot that is partially or completely shaded. This is not to amuse you but as your plant is already hydrated to the extreme, sudden loss of water due to evaporation will make it even more stressed.
  • Remove all the flowers and fruits and some of the top growth so that plant can focus its energy on survival. As the root system of your plant is compromised due to rot, it’ll not be able to support the growth of its extra leaves, flowers, and fruits.
  • From all the sides pat the container repeatedly so that the roots loosen up. Lift your plant up gradually holding the base of the stem.
  • Let the plant stay out for around five-six hours so that the roots become aerated and dry. If you can put it on a cooling rack, it’d even better as the air will facilitate in the drying process.
  • Carefully get rid of the soil infested with mold that is still sticking to the roots. You can do this by putting the roots under running water. Clean gently but make sure not to damage the healthy roots during this process.
  • Cut the root parts that are rotten with a sharp and sterile pruning tool. The decayed parts will smell bad and turn mushy, slimy and dark. On the other hand, a healthy root will be firm and white.
  • Once the roots are pruned, sterilize your pruning tool again.
  • Now choose a new pot with proper drainage holes or sterilize the old one and fill it with new soil.
  • Now plant the affected plant in that pot as you usually do and water it normal water or with cold chamomile tea. Chamomile tea works as a mild fungicide and prevents damping off due to its antimicrobial properties.
  • Keep the pot in a spot that is bright and receives filtered sunlight or several hours of morning sunlight until the plant is recovering.
  • Afterward, water only and only when the soil becomes dry to the touch.

Treatment

Treating the soil with a fungicide before you plant a hibiscus can help protect it from fungal infection. Follow up with soil drenches that fight fungus at least every four months. Fungicides only work if the roots haven't been infected yet. If you catch the disease early enough, you can prune off the affected roots and treat the soil with fungicide before replanting the hibiscus. Treating the plant with a growth enhancer can help strengthen it so it can fight off the disease on its own. Keep the soil moist but not wet so the hibiscus doesn't experience any additional stress while it's trying to heal.

Based outside Atlanta, Ga., Shala Munroe has been writing and copy editing since 1995. Beginning her career at newspapers such as the "Marietta Daily Journal" and the "Atlanta Business Chronicle," she most recently worked in communications and management for several nonprofit organizations before purchasing a flower shop in 2006. She earned a BA in communications from Jacksonville State University.


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