Summer and the scourge of Pythium!

As we enter the warmer months of summer, you may find that some hydroponics growers begin to get a bit of an anxious look on their faces with just a mention of the word “pythium”. Now, while the summer brings lots of long, bright days which are ideal for the fast growing of plants, there is a big problem that comes along with warmth that summer brings, particularly for the hydroponics grower.

Hydroponics involves the growing of plants in a medium where automated feeding and watering takes place, usually involving a reservoir (sometimes very large) which will normally hold enough water/nutrient solution for a whole week.

In a system like this, as the weather gets warmer, the water/nutrient solution gets warmer also. Once the nutrient solution goes over the ideal 18C (65F) mark, two things begin to occur:

1)      The reservoir water/nutrient solution begins to hold less oxygen. This actually goes against what we would normally expect because generally, as a liquid gets warmer, it usually allows more of a substance to be dissolved into it. Not so with oxygen. As water or nutrient solution gets warmer, actually LESS oxygen can be dissolved in it! The problem with this is that roots need oxygen for healthy growth. Therefore, due to the reduced amount of dissolved oxygen, warm nutrient solution can actually cause slowed root growth, which will eventually affect the whole plant. As if that wasn’t bad enough, a reduced amount of dissolved oxygen also causes another problem. Dissolved oxygen helps to inhibit the growth of anaerobic pathogens. As a general rule (but not a hard and fast one), the good beneficial microbes are aerobic (use oxygen) and the bad types are anaerobic (do not require oxygen). Therefore, as the weather gets warmer, conditions in the reservoir tank begin to favour the bad microbes, and this actually compounds the next problem…

2)      The fungus that causes root-rot (pythium) thrives in warm, wet conditions, particularly if the amount of dissolved oxygen is depleted. Therefore, most reservoir tanks in summer become the perfect breeding ground for this scourge of the hydroponic farmer.

Once pythium has taken hold in a hydroponics system, it can completely ruin every plant growing in it within an incredibly short space of time (usually only a few days).  If you’ve ever pulled a struggling/limp plant out of it’s grow medium and found a pathetic dying root system (sometimes covered in slime), then you know the problem that I’m talking about!

On top of that, pythium can be an absolute nightmare to get rid of as there are few treatments out there that can actually kill the fungus, and even fewer that won’t kill your plants. So what can be done by the concerned gardener so that he can get some sleep at night?

The very first step is to ensure that the reservoir is located in the coolest place possible. Make sure it is well out of the way of hot HPS lamps (preferably in a different room) and direct sunshine. The outside of the reservoir can also be insulated to help keep the heat out.

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Secondly, a water chiller can be used to cool the water within the reservoir. A chiller unit sits next to the reservoir with feed and return pipes connected to the reservoir. The chiller draws nutrient solution from the reservoir through one pipe, chills it and then returns the cooled solution back to the reservoir though a second pipe. The chiller will automatically keep the nutrient solution at a constant temperature which is set by the user. 18C (65F) is ideal. The chilled nutrient solution allows more oxygen to be dissolved in the water or nutrient solution. An airstone added to the bottom of the reservoir helps to increase the amount of dissolved oxygen up to its maximum. As a bonus, an airstone helps to keep the solution well mixed. Our opinion is that every reservoir should have an airstone at the bottom. It does so much good that it’s a bit daft not to have one: Air Pumps and Airstones

The third step is to use a preventative product:

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Pythoff has been around for years. It disappeared for a short while but now it is back. It’s an old favourite of seasoned growers that effectively prevents and treats pythium infections. This product effectively keeps the hydroponics system sterile and will also kill any beneficial microbes in the root-zone. Pythoff should be added at every weekly reservoir change on a continuous basis for on-going protection. Add at the rate of 2ml/litre. For a 100 litre reservoir this equates to £6.59 per treatment at current prices.

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Guardian Angel. Used regularly, Guardian Angel will ward off any Pythium attack before it gets a chance to take hold. It manages to do all this without killing or inhibiting beneficial microbes. Guardian Angel should be added at every weekly reservoir change on a continuous basis for on-going protection.  Add at the rate of 0.67ml/litre. For a 100 litre reservoir this equates to £2.01 per treatment at current prices.

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House & Garden’s Roots Excelurator is one our favourite products ever. This magic liquid is truly a wonder product. Roots Excelurator coats the roots of your plants with a fine membrane which allows free passage of nutrients and oxygen to the roots but acts as an incredibly effective barrier to pythium spores attempting to get to the roots. Rumour has it that Roots Excelurator can even eradicate pythium from an infected hydroponics system (this has not tested by us). As a bonus, Roots Excelurator will also encourage root growth like you have never seen before and doesn’t kill beneficial microbes in the root-zone. Because roots are the engine of a plant, this sets up the perfect situation for a bonanza crop. Many growers use this product up until the 2nd week of flowering/fruiting for it’s root stimulating power, and then switch to a product such as Canadian Xpress Regen-a-root + Wilt Guard for the last of the flowering/fruiting stage. Roots Excelurator should be added at every weekly reservoir change on a continuous basis for on-going protection.  Add at the rate of 0.3ml/litre. For a 100 litre reservoir this equates to £3.45 per treatment at current prices.

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Canadian Xpress Regen-a-root + Wilt Guard. Regen-a-root is an excellent product used by many of our shop customers. Using Wilt Guard along with it gives even greater protection against the dreaded pythium. A lot of customers use House & Garden’s Roots Excelurator up until week 2 of flowering/fruiting for it’s incredible root stimulation. Then they switch to using Regen-a-root (or regen-a-root + Wilt Guard) up until harvest time. Regen-a-root (or Regen-a-root + Wilt Guard) should be added at every weekly reservoir change on a continuous basis for on-going protection.  Add at the rate of 1ml/litre. For a 100 litre reservoir this equates to £1.45 per treatment at current prices (or £3.29 if using Wilt Guard as well).

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Plant Magic Plus Pyth Tabz is a brand new product on the market. One tablet will treat up to 120 litres of nutrient solution and costs £4.95 and should be used weekly after every reservoir nutrient solution change-out. As they are a new product, we have not had chance to try them out yet but from experience we know that Plant Magic products are always of the highest quality. This product cannot be used with beneficial microbes as it effectively sterilises the hydroponics system.

As Pythium can destroy your crop in such a short period of time, it is wise to be prepared. Set up your reservoir in the correct place, use a water chiller if possible and use one of the preventatives mentioned above (especially Roots Excelurator for the added bonus of an incredible root system). Peace of mind can be yours, if you think ahead!