Black Spots on Pepper Roots in Hydroponics

Nutrient Solution Hydroponics

• Hydroponic systems can cause root damage when they are not properly maintained. The most basic kind of hydroponic system is composed of a polystyrene foam float with holes through which plant roots grow. Roots are suspended in a nutrient solution. The foam platform floats on top of the nutrient mixture. Air pumps continually pump oxygen through the solution to provide aeration. Without aeration, the nutrient solution becomes stagnant. Stagnant nutrients provide a growth medium for bacteria and other unwanted pests. If peppers with black spots on their roots are found in nutrient solution hydroponic systems, check to ensure the aerators are working properly. Drain the infected nutrient solution and remove diseased plants. Keep healthy plants and submerge them in the aerated nutrient solution.

Liquid Systems

• Other slightly complex hydroponic systems are the ebb-and-flow system and the drip system. The ebb-and-flow system floods a nutrition tank with nutrient solution. The solution bathes suspended root systems, then drains from the tank back into a central reservoir. At timed intervals, the solution leaves the reservoir, floods the tank, supplies the roots with nutrients and drains back into the reservoir. The danger with the ebb-and-flow system lies in the recycling of possibly infected solution. The same is true for drip systems. Instead of flooding a tank drip system, bath root systems at timed intervals. These systems allow harmful growths when not maintained or when used in poor settings. Warm temperatures encourage bacterial growth. Greenhouses or grow rooms can harbor insects if plant debris isn't clean and solution isn't sterile. These conditions allow fungus gnats to gain entry into the solution. Fungal gnats and bacteria have the potential to damage delicate pepper plant root systems and leave black spots.

Aggregate Systems

• Aggregate systems most often are used in pepper plant production. Rough gravel or coarse steel coil provide anchorage to large plants and encourage healthy root systems. Aggregate systems provide a growing medium but are bathed in nutrients in much the same way as liquid-only systems. Roots are damaged by warm temperatures or exposure to bacteria, viruses and pests. Should black spots occur on pepper plant roots housed in aggregate, sterilize or destroy aggregate materials and replant healthy pepper plants.

Considerations

• Prevent the possibility of root rot and mosaic virus by choosing disease-resistant varieties. Purchase new seed annually and do not reuse old seed. If you are growing pepper plants from transplants, inspect the plants before purchase. Pay attention to diseased roots or lower stems. Keep greenhouse and grow-room temperatures within the 70- to 80-degree Fahrenheit range during daylight hours and 60 to 70 degrees at night.