Our hydroponic rose garden was flourishing after transplant. A healthy new root system had developed, and was extending into the great depth of highly aerated nutrient solution that the Under Current XXL system offers. The roots had been happily feeding on ultra-premium hydroponic base nutrients with a variety of nutrient additives, especially microbial products that supplied enzymes, carbohydrates, beneficial fungi and bacteria to the mix.
Big buds had been popping off up top and growth was squat and robust; a picture-perfect hydroponic rose garden.
The grower, with years of hydroponic growing experience, knew the potential pitfalls of creating too great a microbial load when applying additives, especially with nowhere for populations to go as is the case with hydroponic systems that maintain plants with bare roots.
The nutrient solution was beginning to run a little warmer due to seasonal changes, and then all of a sudden something happened. The pH began a wild ride upwards; no amount of pH adjusters could keep it stable. A thick mucus-like substance began to build up in the system and cover the bare plant roots. Left unabided, the invading slime began to take over, and soon plant health suffered. All the symptoms manifested very quickly once the outbreak had begun. How did this all happen? An excessive and unbalanced microbial load had been created due to:
1. Trouble Brewing
The cloudy-looking reservoir solution is a sign of trouble. Notice the scum accumulating on the inner wall of the reservoir with nowhere else to go. Two things may commonly be attributed to cloudy nutrient solutions when they are otherwise transparent: a) the pH is running too high (over pH 7.5), causing nutrients to “flocculate” or precipitate out of the solution, or b) a serious microbial overload, with organic particulate from decaying root matter and new organic substances forming from combinations of organic-based nutrient additives.
2. Root Choke
Here we see that the insidious brown slime globbing onto what was formerly a healthy, white, spaghetti-like root system. The roots did not have root rot, but the slime began to strangle them of oxygen while robbing other nutrients, creating root decay which acted as a food source to further the problem. Once the infection/outbreak cycle has started, the decaying matter becomes akin to throwing gasoline on a fire.
3. Yellowing Leaves
The lower leaves are beginning to yellow. Before the attack, the plants created big blooms and lots of branching. Now, as the root system deteriorates, the plants cannot take up enough in the way of nutrients to support the structures created during healthier times. The leaves begin to yellow as the plant exhausts itself of nutrients.
4. Cloudy Water = Problems
Draining the system is the first step to recovery. Keeping a close eye on the drain-water can tell you more about the health of the system. In this case, the water is clouded. Upon close examination, it’s easy to see that it’s full of organic debris. Unfortunately, a lot of this debris is decaying root matter from what was once a healthy and vibrant root system supporting the crop.
5. Heart of the Problem
Here in the epicenter, we find the oxygen generator for the system. The black dome in the center of the frame is a porous oxygen diffuser. Notice how covered it is with the slimy menace, also seen on the side of the container and in the lines. The old clouded solution is being pumped away with the garden hose.
6. Slimy Stones
One of the differences here versus common hydroponic root rot is that the attacker seems to love oxygen; so much so that it created a stranglehold on the air diffuser. This created a situation where the plant roots had limited access to higher O2 levels, signifying that the slime was intelligent enough to make an effort to outcompete the root system. The airstones were boiled after sterilization to ensure no invading slime remained.
7. H2O2 to the Rescue
Food-grade, high-content hydrogen peroxide (H2O2). This particular bottle is 29% concentration (although 35% grades are available). In contrast, the stuff you get from the drugstore is 3%. As a last-ditch effort to kill off all microbes and bio-life in the system, the H2O2 is being added to fresh, pH-adjusted water (after the system was drained and refilled) at a rate of 10ml per U.S. gallon (3.78L). The H2O2 solution was circulated for a few hours, pumped out, replaced and circulated again. Wear gloves and goggles when handling concentrated H2O2.
8. Free From Scum
After several washes and refills with pH-adjusted H2O2-enriched solution, the neutralized scum was drained and skimmed out of the system, leaving the damaged roots free at last to breathe. While the damage has clearly been done, this provides a chance for recovery and regeneration of the root system. Top growth was pruned back so the decreased root mass wouldn’t be overworked relative to the green and blooming regions of the plant.
9. New Beginnings
This is almost two weeks after the initial H2O2 treatment. Look closely and you will see the old root system has continued to decay. However, healthy white new roots have been emerging to take the place of the old root system and sustain the plant until all of the new root mass can support healthy new vigorous growth.
10. Back on Track
Finally, after several weeks from the initial H2O2 treatment, there is little, if any, trace of the disaster that occurred only a few weeks ago. It appears that the strong surge of oxygen that may result from careful applications of hydrogen peroxide not only sterilized the system, but may have also helped to trigger healthy, new and problem-free root growth. In essence, “oxygen therapy” was performed on the plants, saving the crop.
Several lessons were learned here. Most significant was the power and flexibility of hydroponics. Growers who are intimidated by true hydroponics systems may fear encountering root diseases. While it’s true that root diseases can occur in hydroponics, they can also occur in soilless and soil-cultivation methods just as easily. The striking difference is that hydroponics may allow growers to cure plants and recover, where with conventional methods the crop would likely have been a total loss.
Next time you encounter a growing disaster, know that you aren’t alone and that often there is the possibility for recovery with proper management and understanding of modern growing techniques like hydroponics. Remember, like the almighty Mr. Burns said to Homer Simpson, it can’t be plaques and hams all of the time.
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Monday, 12 March 2012