Pythium – The Hydroponic Plague

Pythium – The Hydroponic Plague

Pythium is a big problem when growing using hydroponic methods, especially when the summer approaches and grow room temperatures rise. But what is Pythium? What causes Pythium and how can Pythium be stopped?

What is Pythium?

Pythium is name of a family of fungus-like microorganisms (recently re-classified as plant parasites), but commonly called water moulds. Pythium plays a large part in the condition damping off, which kills seedling in cool, damp, or high humidity conditions (hence the name damping off). This is because the spores require surface water to travel. Which in field crops means the damaged caused is often localised to areas of poor drainage. In hydroponics however, the flow of nutrient solution acts as a perfect delivery system for the Pythium spores to spread. The natural capillaries in soil and coir act as a filter to the spores, reducing the spread, but the bare roots in hydroponic provide easy access.

As the spores travel via water, the first tissue it meets is often the root system. This leads to Pythium-induced root rot, which starts by reducing the vigour of the plant, causes wilting and yellowing (and other signs of deficiencies) of the leaves and the roots turn from white, to brown. As the roots become further infected, they turn darker brown, appear slimy and begin to decay and die. With the death of the roots, the plant also dies, but not before allowing Pythium to produce millions of spores to spread the infection.

The two biggest problems with Pythium are:

1. Pythium can survive on decaying plant matter for a long time after the plant has died. This means that unless everything is completely cleaned and a strict hygiene regimen is followed, the infection will remain in your grow room.
2. Pythium is unspecific in the types of hosts it attacks. This means that it will infect a wide variety of different types of plants. Rotating crop types won’t avoid the dormant spores in the grow room.

How do you stop Pythium?

There are a few ways to prevent or minimise the impact of Pythium. With seedling, avoid sowing them too close together, as this reduces air movement, leading to the humid conditions that cause damping off. The standard advice for any grow room is important. This means keeping good airflow, controlling humidity to between 40-60% and maintaining good hygiene practises.

Pythium is often a secondary infection; this means that it usually attacks a plant when it’s been damaged or is suffering with non-ideal growing conditions. So just by keeping your grow room ventilated and your plants healthy you can reduce the chances of a Pythium infection.

Because Pythium is such a big problem for hydroponic growers, there are products out there to stop Pythium from damaging your crop. You can use UV light or peroxide based products, but these can be expensive and detrimental to your crop, as there is a fine line between killing Pythium and killing your plants. Another avenue of approach is the array of liquid based sterilisers often utilising chlorine. We recommend using products such as PUROLYT or Silver Bullet.