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How to Treat Phytophthora Root Rot

By Daisy McCarty

Phytophthora root rot is a serious fungal infection that attacks many types of vegetation. Shrubberies, woody ornamental species and some fruit-bearing cultivars are its most common hosts. According to plant pathologists at Auburn University, prevention is the best way to keep your plants safe from this disease. Excessive irrigation and lack of drainage are common precursors to fungal plant infection. Often, by the time symptoms become obvious it is too late for chemicals to save the diseased hosts. Root rot is prolific and can kill affected shrubs within weeks.

Keep records of areas, fields, containers or beds that have a history of hosting root rot fungus. This pathogen frequently remains dormant in the soil as a spore. When the right conditions arise, it will multiply rapidly and become a serious problem.

Identify early signs of the disease whenever possible. Above-ground symptoms include excessive yellowing of needles or leaves near the crown, wilting, death of branches, and poor growth. The whole plant may begin to take on a bronze-colored appearance. These are also signs of many other diseases, so get a lab test for confirmation of a suspected case.

Select an appropriate treatment or management method. Phosphonate fungicides such as Chipco Aliette, Chipco Signature, Stature and Subdue MAXX will abate the growth of Phytophthora root rot. Unfortunately, the use of some fungicides will hurt efforts to build a certified organic stock. Isolation and irrigation review is often a viable alternative in these cases.

Apply fungicide to the affected plants by drenching or spraying. Use appropriate safety equipment such as gloves and goggles and adhere to all safety precautions on the label. Follow strict sanitization procedures for any containers that may have been contaminated with fungal spores.

Monitor the results. Consider performing monthly maintenance with low doses of fungicide as a cost-effective preventive measure.


Things You Will Need

  • Record-keeping supplies
  • Contact at a plant pathology lab
  • Fungicide
  • Applicator


  • Substitute highly resistant strains and hybrids of cultivars for susceptible plants whenever possible. Use raised beds or mounds to promote proper moisture control.


  • Many fungicides are highly toxic. Review all available material safety data sheet (MSDS) information before buying or using a fungicidal product.

About the Author


Daisy McCarty is a freelance writer in the Dallas - Ft Worth area of Texas. She specializes in creating informational web content and training materials. Some of her favorite topics include human resources, martial arts, interior design, fashion, gardening, and health/medicine.