Phytophthora Root Rot

Shrubs affected by phytophthora root rot.Phytophthora Root Rot is an extremely damaging and widespread fungus like organism that will rot away your trees/shrubs root system and eventually kill your tree if left untreated. In the worst cases, when left untreated trees can become structurally unsafe and uproot or snap possibly causing property damage and injury. On older plants may show symptoms for a season or more before death; however, younger plants can die within two weeks of showing symptoms.

Because of the high levels of rain we received in the last week, our Arborists warn that homeowners may start to see signs of Phytophthora Root Rot on their trees and shrubs.

Susceptible Species:

Phytophthora affects a wide range of plants. In the DC Metro Area the following plants are most susceptible to Phytophthora Root Rot:

Azalea, rhododendron, dogwood, pieris,  yew bushes, deodar cedar, mountain laurel, heather, juniper, Fraser fir, white pine, shortleaf pine, camellia japonica, aucuba, and more.

Phytophthora root rot symptomsAbove Ground Symptoms Of Phytophthora Root Rot include:

  • Suppressed growth
  • Poor Vigor
  • Yellow or undersized needles/leaves
  • Premature needle/leaf drop
  • Branch dieback
  • Drooping of leaves
  • Curling of leaves
  • Leaves turning brown
  • Death – if not treated or removed
  • Loss of dark green color

Factors Favoring Phytophthora Root Rot

High soil moisture and warm soil temperature favor Phytophthora Root Rot. The disease is common in areas where run-off or rain water collects around the roots of plants. Overwatering your plants can also lead to the development of Phytophthora.

Prevention & Treatments:

Purchase Disease Free Plants: Since most plants never truly get rid of Phytophthora Root Rot once infected it’s very important to make sure the plants you buy are disease free.  Buy plants at a reputable nursery and avoid plants that lack normal green color or appear wilted.

Plant Root Rot Susceptible Plants in Well Drained Soil: Some plants are highly susceptible to Phytophthora Root Rot which means that if given the right conditions they will most likely contract Phytophthora and die. It very important to plant these species in well-drained soil since slow draining and wet soils are great breeding grounds for Phytophthora.

Camellia sasanqua - resistant to Phytophthora Root Rot

Camellia sasanqua – resistant to Phytophthora Root Rot

Plant Resistant Plants Especially In Wet Soil: Just as some plants are susceptible to Phytophthora Root Rot, some plants are naturally resistant. When you have soil conditions that favor Phytophthora you should always plant resistant cultivars.

Certain types of rhododendrons: Caroline, Martha Isaacson, Professor Hugo de Vries and Red Head

Certain types of Azales: Rhododendron poukhanese, Formosa, Fakir and Corrine Murrah

Camellia sasanqua is resistant as wells not to be confused with Camellia japonica which is highly susceptible to Phytophthora Root Rot.

Fungicide Treatment: The spread of Phytophthora Root Rot in an already infected tree/shrub can be reduced through the use of properly applied fungicide treatments. Fungicide treatment can also help stop the spread of Phytophthora to other plants in your landscape.

Tree Removal: In certain cases removing a tree infected with Phytophthora Root Rot is the best choice. Trees that already suffered extensive root damage are not structurally safe and can snap and uproot in a storm. Trees in this situation are extremely dangerous and need to be removed as soon as possible.

If you think your trees or shrubs are infected with Phytophthora Root Rot book a consultation with our Arborist online or by calling 703-573-3029. Our Certified Arborists will be able to develop the best treatment and help you institute preventative measure to stop the spread Phytophthora Root Rot to new trees/shrubs.

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Samantha Huff

Samantha Huff is the marketing coordinator at RTEC Treecare. She enjoys learning about the technical aspects of trees and the insects and diseases that prey on them. She hopes that these articles can help homeowners gain control of their tree and shrub maintenance by being aware of the signs and symptoms of unhealthy trees.

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