Identifying The Common Signs Of Plant Disease

There are a few key markers that indicate the success of the pathogenic bacteria over the beneficial ones.


  1. Your roots will begin to smell “off” or “swampy”

  2. The roots will begin to look black and slimy

  3. The overall growth will be slowed.

  4. The leaves will begin to turn yellow, eventually leading to the death of your plants

  5. Fuzzy white powder or web-like strands will be found on your leaves or in the soil/substrate of your plants

  6. Black spots will be found on the leaves alongside discolorations and curling

  7. Discolored rings will form all over the surface of the leaves suddenly


As pathogenic bacteria or fungal colonies begin to grow, they will begin to become visual in your plant's root zone. The healthy, white roots will begin to darken, and die. You will notice extra particulate in your water and the roots will start to look and feel slimy.

These colonies grow exponentially, meaning that the larger they get, the faster they grow, making it crucial to stop the problem early and shift the balance in favour of the beneficial microbes.


A Guide To Plant Pathogens

Once you have noticed the infection of pathogenic bacteria in your hydroponic garden, it is absolutely crucial that you begin treating the problem promptly.

It is not realistic to test for the exact species that is infecting your garden, nor is it necessary. Determining the difference between fungal, viral, or bacterial infection, however, can make a difference in your treatment aims for the problem.



When it comes to bacteria, the key differential factor is the presence of a slimy, brownish coating on the roots of your plants. This coating can also be found growing along the walls of your reservoir, up hoses and tubing, and in the water pumps filter.

Bacterial infections can easily be prevented with the use of beneficial microbe additives, or by changing the reservoir out regularly.

Treating bacterial infection begins with a thorough reservoir clean, making sure to disinfect all of the surfaces before filling it back up with water. An application of a mild hydrogen peroxide solution can be helpful in killing off many of the remaining bacterial cells left behind. After a few days, once the hydrogen peroxide has been depleted, beneficial microbes should be added to further fight and kill of the pathogenic strains.



Fungi can be identified by the presence of web-like, powdery, or fuzzy growths in the roots, soil, or on the leaves of your plants. The color can vary between grey, blue, white, and green.

Treating fungal diseases will involve a thorough reservoir clean, as well as the application of an antifungal agent. For powdery mildew, the best treatment is products containing the beneficial bacteria Bacillus Subtilis. This bacteria quickly kills the fungus, and coats the leaves to prevent further infection.

Soil borne fungi can be prevented with beneficial additives, and are easily treated with antifungal sprays or additives.



One of the most deadly pathogens for a hydroponic garden is a fungus-like organism known as pythium. Infection with this organism is characterised by a definite blackening of the roots, foul odour in the root zone, and slowed or completely halted growth of the plant.

This organism will quickly spread between your plants, and often leads to the complete destruction of a crop.

Treating this organism is difficult because it tends to hide inside the plants roots themselves. Hydrogen peroxide treatments can significantly slow the growth of the organism, but isn't enough to completely stop the infection. The best course of treatment is to isolate infected plants from the rest during treatment, and immediately change the reservoir water.

With a pathogen such as pythium, prevention is by far the best treatment. Use beneficial microbes like mycorrhizae early and often with your plant to prevent the ability for a root rot organism like pythium from ever having a chance to thrive in your garden in the first place.



Yes, plants too can become infected with viruses, and the prognosis is almost always fatal. Although viruses are rare, they do happen from time to time in the hydroponic garden, mainly brought on by insect invasion, outside soil use, or from the introduction of mass grown plants into the hydroponic garden. In large greenhouses, dealing with numerous plants that are all identical, viruses can spread quickly and silently through the crop.

Viruses often hide dormant in plants, coming out suddenly later on. By the time they show themselves they may have already spread far and wide amongst your crop.

The best way to prevent viruses from spreading is to sterilise your tools between trimmings and prevent insect outbreaks promptly and effectively. If a plant is found to have a virus, immediately remove the plant and discard it. There is no way to save the plant and the longer it stays in the grow room with a viral outbreak, the more likely the virus is going to find its way into other plants as well.

A viral outbreak will quickly lead to the total destruction of your crop if left unchecked.



When it comes to plant diseases, it's important to know the main characteristics that indicate what type of disease it is. Bacterial and fungal infections are easily treated with the right products, but with the wrong treatment will quickly develop into a serious problem.

Pythium and viral infections are less common, but have a far greater destructive impact on your garden.

With all of these diseases, the best treatment is actually in prevention. Using beneficial microbes, sterilising your tools between switching plants for trims or cuttings, and regular reservoir changes can go a long way in keeping your plants healthy and disease free.