Cotton Root Rot Cotton Root Rot has different names such as Texas root rot, Phymatotrichum root rot, Phymatotrichopsis root rot, Ozonium ...
Cotton Root Rot
Cotton Root Rot has different names such as Texas root rot, Phymatotrichum root rot, Phymatotrichopsis root rot, Ozonium root rot (in olden literature), Etc., It is a hazardous pathogen. You can commonly find it in the southwestern US, some parts of south-central US, and Mexico regions.
Generally, Cotton Root rot (Texas Root Rot) causes wilt and ruins affected plants, particularly during the summer months. This soil-borne fungus (Phymatotrichopsis omnivore) directly attacks the roots of the vulnerable plants.
This disease has affected more than 2,300 species of healthy plants and ruined them.
Generally, this fungus spreads from infected trees to other healthy trees across the garden. Hence, controlling this disease is an extremely difficult task.
Normally, this Fungai mostly targets dicots (dicotyledons) as they are more vulnerable to soil-borne fungus and other diseases.
Generally, monocots (Monocotyledons) have high immunity and can survive this disease.
Favorable Environment (Texas Root Rot)
Cotton Root rot (Texas Root Rot) prefers to thrive in humid and hot weather conditions. It is because this disease can infest more vigorously under these conditions.
During this type of environmental condition, the plants become more dependent on their roots for essential water and nutrients. Thus, this disease can infest the whole plant quickly through the roots.
Moreover, this fungus prefers alkane calcareous soils. It is because this type of soil rarely freezes and also can survive cold weather radially. It is also known to retain warmth to some extent.
Due to the above facts, this disease is largely restricted to southwest US regions.
Infecting methods
When the plants suck water and other nutrients, this fungus enters the trees through its roots.
Using infectious hyphae, this fungus covers the epidermis of the plants and infects them. Then, it infects the vascular systems. It also neutralizes the defense systems and infects the whole tree. Ultimately, the infected trees die with no option to resist.
Identification of Cotton Root rot (Texas Root Rot)
Normally, you can find the symptoms during warmer months especially from June to September. During this period, the soil temperature rises more than average. In addition, the air temperature also exceeds 100-degree Fahrenheit.
At the initial stages of infection, the upper leaves of the tree die, followed by lower leaves. Simply speaking, the leaves turn brown and remain sticking to the plants.
It looks the tree is suffering from water stress. But in fact, the Cotton Root rot (Texas Root Rot) disease is at the initial stages. After that, the tree starts wilting, loses shine, and finally dies.
Mostly, you can find the decayed roots with a blurry tan-colored mold covering them. You can also easily peel off the barks. Upon doing so, you can find the inner white woody tissue showing a reddish-brown stain. You can also see white spore mats on affected trees often.
If you examine further, you can find extensive discoloration of the host plant’s vascular system. There will be more observable signs under the soil, especially on the roots.
If you examine the root structure with a microscope, you can find Distinct cuniform branched hyphae on infected roots. In addition, you can find mycelial strands covering the taproots.
After the trees die, Sometimes, white spore mats develop on the surrounding soil too. These white spores slowly turn tan. Finally, they disappear after a few days, without further spreading. This is the unique feature of the Cotton Root rot (Texas Root Rot) disease.
The Lifespan of the Disease
The life span of the Cotton Root rot (Texas Root Rot) inside the soil is almost indefinite.
The corresponding fungus creates sclerotia (tiny resting structures) inside the soil. Thus, the disease shelters inside the soil. Some soil experts found these seed-like structures as deep as 12 feet inside the soil.
The sclerotia germinate radially when the soil temperature rises above average, thereby infecting the plant roots in the vicinity. After that, the infected roots transmit the disease to other plants’ healthy roots upon contact. In this way, the disease spreads abruptly.
This disease also survives in some native vegetation roots like mesquite roots. Therefore, they can spread across the area vigorously.
Treating Cotton Root Rot (Texas Root Rot)
Most soil-borne fungus diseases are very difficult to control, especially, Cotton Root rot (Texas root rot).
Generally, there are some methods available to reduce the intensity or severity of the disease. But none of them are proven to be highly effective.
Cutting the Infected Portion
If you find the disease at the initial stages itself, cut the top growth of the tree by almost half. After that, keep the affected tree moist for some weeks.
In this method, you can technically reduce the stress on the tree roots. So, there is a chance that the roots fight back the disease and attain normal growth once again.
Treating the Soil
You also try your luck by changing the alkaline properties of the soil. This may not work every time.
Along the drip line, form soil ridge. Dripline is the approximate root extension of the tree. It is approximately the same as the spread of the tree.
Fill the inner ridge with raw cow manure or other organic matter for about 1-2 inches deep.
Also, mix sulfur and ammonium sulfate at a proportion of 1 pound every 10 square feet individually to the inner dripline basin. This helps to change the alkaline properties of the soil to a greater extent.
After that, flood the basin with water so as to soak the soil minimum of 3 feet deep.
Repeat this procedure every year. Otherwise, the soil may return to its original alkaline state, thereby catering to the deadly disease.
Amending the soil with Chemicals
You can also try amending the soil with chemicals, thereby increasing soil microbes.
Add some organic matter or green manure to the soil. This will increase the count of the soil microbes. They can effectively compete or sometimes even neutralize soil fungus.
In addition, some studies indicate the green manure decomposes and releases chemicals into the soil. These chemical compounds can inhibit soil fungus.
The next reason for preferring this method is, the tree roots grow vigorously and healthy in manure-rich soil. This growth, in addition to health, will help resist the fungal disease to some extent.
This method is often proved a success in resisting some other fungal-infested soil diseases also.
Plowing the Surface
Try plowing 6-8 inches deep. In this method, you can destroy the fungus in the upper layer of the soil. Most plants and some trees spread their roots in the upper layer of the soil. So, this method can prove to be effective for such plants.
But there are some plants and trees which grow roots deeper and deeper. If the disease survives in lower layers of soil, it can affect such roots. This method may not be much effective for such trees.
Planting Cotton Root rot (Texas Root Rot) in the Infected soil
If your soil is already affected and you have lost some of your trees, do not replant them in the same spot. This disease can survive in the soil almost indefinitely.
So, consider planting some plants which can resist Cotton Root rot (Texas Root Rot) disease. For Instance, Monocots (grasses) are known for their resistant characteristics against this fungus.
Economic losses Due to this Fungai
This pathogen has adversely affected the economies of many countries including the US.
For instance, the cotton industry suffered a huge loss amounting to $100 million annually in the previous years. You can find this data in the National Cotton Council of America’s database.
This disease can also cause a substantial yield loss in horticultural crops such as ornamental trees, apples, peaches, peanuts Etc.
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