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April Showers Bring May Fungal Diseases

Springtime is the mark of new beginnings and growth; however, not all growth is welcome, especially fungal diseases that may destroy your trees. The cool moist weather of early spring days, like the weather the DC Metro area has been experiencing this spring, creates the perfect breeding ground for fungal diseases. Learn which fungal diseases to look out for this spring and how to keep your trees/shrubs safe.

How Fungal Diseases Are Spread:

If your tree or shrubs had a fungal disease last year they will most likely get it again this season. That is because fungal spores aren’t killed by the cold winter, they overwinter in fallen leaves and soil and are reawakened by the rain and semi-warmer weather in the spring.

Fungal spores can spread through:

  • the air on windy days
  • hard rains that splash the spores up onto trunks and leaves
  • gardening tools
  • Human movement; for example, walking through wet diseases plants then walking through healthy plants that aren’t yet infected.

Common Symptoms of Fungal Diseases

  • Mushrooms at the base of the tree
  • Irregular patches of brown and black discoloration on leaf
  • Black pimples
  • Blotches along leaf vein
  • Cankers on the twigs and branches
  • Distorted areas on leaves
  • Early leaf drop
  • Discoloration of bark/trunk

Need Help With Fungal Diseases?

Or Call 703.573.3029

Fungal Diseases To Look Out For This Spring:



Anthracnose is a tree fungus that is active in the spring when the weather is wet and cool. Overwintering in fallen leaves, this fungus will continue to infect your tree year after year if not treated. Multiple infestations can leave trees stressed and susceptible to secondary invaders.

Symptoms: tan to brown leaf spots which many have purple rings around them, wilting, defoliation, dieback, leaf blotches.

Targets: Dogwoods, Ash, Oak, Sycamore, Birch, Walnut, Tulip, Hickory, and Maple

*In the spring our arborists see a TON of Dogwood Anthracnose. If you have a dogwood (with the exception of Kousa Dogwoods), your tree should be on a preventative fungicide treatment this spring*

Learn more about Antracnose


Crepe Myrtle Pruning 4

Sooty mold is a fungus that grows on top of honeydew (the excrement of plant-sucking insects) and coats the leaves to the point where they can no longer absorb sunlight. This interrupts photosynthesis and the tree will not be able to produce the nutrients they need for survival. If your trees and shrubs are turning black you most likely have a sooty mold problem caused by an insect infestation.

Targets: Typically seen on rose, ash, oak, elm, maples, willow, and fruit trees.


Powdery Mildew

Powdery Mildew is a tree fungus that coats leaves blocking the process of photosynthesis.  Every year trees and shrubs rely on photosynthesis to create food for new leaf growth. When this process is interrupted by powdery mildew the food reserves aren’t replenished and the tree/shrub’s growth will be stunted which can affect overall health. The stress caused by Powdery Mildew also makes the tree more susceptible to other diseases and insect infestations.

Symptoms: Powdery mildew is characterized by spots or patches of white to grayish, talcum-powder-like growth on the upper side of leaves.

Targets: A wide range of plants but Lilacs, Peonies, Dogwoods, or Crape Myrtles are especially susceptible in this area.

Learn more about Powdery Mildew


Cercospora Leaf Spot On Rose

The tree fungus begins as a small spot on the leaves. As the disease progresses more spots appear until the leaf ceases to function as the site of the tree’s food production process and falls off of the tree.

Symptoms: Round leaf spots (may have purple or dark brown borders), tiny black flecks (fungal spores) in the center of the spots.

Targets: Wide range of ornamentals, shade trees, and plants. Our Arborists report that White Oaks are especially susceptible in our area.

Learn more about Cercospora Leaf Spot


Phytophthora Root Rot

Phytophthora Root Rot is an extremely damaging and widespread fungus like organism that will rot away root systems 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.

Symptoms: Suppressed growth, yellow or undersized needles/leaves, dieback, drooping and curling of leaves, leaves turning brown.

Targets: Wide range of plants. The most susceptible include Azalea, rhododendron, dogwood, pieris,  yew bushes, deodar cedar, mountain laurel, heather, juniper, Fraser fir, white pine, shortleaf pine, camellia japonica, aucuba.

Learn more about Phytophthora Root Rot

What Can You Do To Prevent/Fight Fungal Disease:

  • In the fall, rake all leaves and dispose of them. This will keep fungal spores in those leaves from being reactivated in the spring.
  • Don’t overwater your trees in the spring & make sure your soil drains properly. The soil should be moist (some dry patches are okay) but it shouldn’t be so wet you could make a mud ball. Learn more about proper watering.
  • Keep your trees/shrubs healthy overall. Bio-stimulants and proper pruning can boost your trees immune system which will lower the likelihood of infection after being exposed to fungal diseases.
  • Fungicide Treatments. Preventative treatment is best to keep your tree healthy and protected from spring fungal diseases. However, if your tree or shrub is already suffering from a fungal disease a Certified Arborist can help restore your tree’s health through specialized applications of fungicides and other overall health treatments.

Need Help With Fungal Diseases?

Or Call 703.573.3029

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