Root Disease in Hydroponic Gardening

Recognizing Root Rot

• Root disease is often first noticed when plant leaves develop tip burn or begin to wilt. Infected roots are generally brown and have fewer root hairs than those of healthy plants. The roots may also be soft, stunted or have lesions or other discoloration. Recognizing which specific pathogen is affecting the plants may be difficult as many exhibit the same or similar symptoms.

Possible Pathogens

• Hydroponic systems create an environment with limited microbial competition or antagonism that favors the development of pathogens, once introduced. According to the Colorado State University Extension, Pythium is the pathogen most commonly responsible for root rot in hydroponic systems. Other possible fungal diseases include Fusarium root rot, Phytophthora and Rhizoctonia. Identifying the specific pathogen may prove challenging, but they are all prevented or addressed by using similar techniques.

Plant Care and Prevention

• Proper cultural practices, including good sanitation, will help prevent the presence of or limit the impact of fungal pathogens. Use or produce only pathogen-free transplants -- even one infected transplant can lead to an epidemic. Sterilize materials, surfaces and equipment regularly and between crops with chlorine bleach or commercial-grade, hydrogen peroxide-based cleaners. Encourage healthy plant growth as most pathogens are able to infect and cause greater damage if plants are already stressed. Keep the solution temperature below 80 degrees Fahrenheit, ideally between 68 and 72 degrees. Avoid over-fertilizing the plants by using a balanced nutrient solution. Increase the dissolved oxygen level through proper aeration. Filter water from outside sources and maintain good insect control. Beneficial microbes can also be introduced to reduce the impact of pathogens.

Treating Infected Systems

• If root diseases are diagnosed, the best course of action may involve disposing of all plants and thoroughly sanitizing all system components if the infection is widespread and serious. For less significant infections, there may be treatment and recovery options. Consider using a fungicide designed for hydroponic systems. Alternatively, remove the plants from the system, sterilize all system components, trim off the infected, brown roots, dip the plants in a sanitizing solution then return them to the system. It may be best to reduce the concentration of nutrient solutions while the plants recover.