Stop Sudden Oak Death This Fall


Sudden oak death (SOD) is the common name for a fatal tree disease caused by Phytophthora ramorum, a species of oomycetes that are similar to fungi. SOD is one of 59 species of Phytophthora, all of which cause disease in plants, such as coast live oak, California black oak, Shreve oak, tan oak, and canyon live oak. Unlike many Phytophthora species that infect roots, P. ramorum is mainly a foliar pathogen. Best outcomes are in susceptible trees treated prophylactically in fall to minimize the risk of spreading this deadly infection.

Identify the Symptoms

Oak leaves will appear stressed, sometimes turning dull green, yellow, red, or purple as they wilt. Infected bark will appear water-soaked, with red-brown discoloration and has a disagreeable odor. Bleeding cankers form at the base of the trunk and eventually lead to death. SOD symptoms are very similar to other common fungal infections. A positive identification of the disease requires sending a tissue sample to a qualified lab.

Treat with PHOSPHO-jet

Arborjet recommends a two pronged approach to treatment. First, the use of PHOSPHO-jet, a systemic fungicide for treatment of Sudden Oak Death into susceptible host trees. Next improve the soil around the tree with high quality organic matter, as Phytophthora thrives in poorly drained and anaerobic soils.
Generally, the best seasons for injection are fall and spring, as uptake occurs when trees are transpiring. The environmental conditions that favor uptake are adequate soil moisture and relatively high humidity. Tree health will also affect treatment efficacy, so assess tree health prior to treating. For example, a declining tree with less than 50% canopy dieback is a poor candidate for treatment. Best outcomes are in susceptible trees treated prophylactically.

Tree Recovery After Treatment

Tree recovery will be dependent upon the severity of the infection at the time of trunk injection. PHOSPHO-jet acts as a fungicide and, as an added benefit, stimulates new root growth. The addition of humates like those found in NutriRoot™ will create a soil environment that favors root growth and increased nutrition over disease development.

Do you have questions about SOD or other tree diseases? Would you like to speak to one of our highly trained service providers? Contact us!