API Summer 2021

problem and provide recommenda- tions, but operators can be proactive and spot the issues before they become major problems.

severe enough, can lead to tree decline. But parasitic fungi have a role to play in ecosystems and often can live in trees for decades without causing trees to die or fail, so their presence should not automatically condemn a tree. Make sure you are familiar with the par- asitic fungi in your area (there are likely only a handful of them) and know how to identify them. Fungal fruiting bodies come in all shapes and sizes, and are often specific to tree species.

KNOW YOUR SPECIES

When it comes to reading biotic signs, it helps to know your species. For exam- ple, most fungi are beneficial to trees, and only decompose already dead organisms. These fungi are referred to as saprophytes. However, there are some decay-causing fungal diseases; these are called parasites. Parasites, if

Understanding the health, growth rate,

Above left: Wilt or discoloration in the veins of leaves is a symptom that can be related to nutrient deficiencies, drought stress, insect damage, and more. Left: Advanced sonic tomography performed due to presence of Ganoderma applanatum conk. The presence of a fungal conk does not always mean a tree should be condemned. Consult with an ISA certified arborist and Qualified Tree Risk Assessor to gain more informa- tion and make educated decisions.

OBSERVATION

BIOTIC OR ABIOTIC CAUSAL FACTOR?

SIGN OR SYMPTOM?

Bird holes in trunk

Biotic

Sign

Off-colored canopy (yellowing)

Abiotic or Biotic

Symptom

Canopy dieback

Abiotic or Biotic

Symptom

Leaf wilt

Abiotic or Biotic

Symptom

Leaf holes

Abiotic or Biotic

Symptom

Stunted or contorted growth

Abiotic or Biotic

Symptom

Conk (fungus) on trunk

Biotic

Sign

Pitch flow on trunk

Abiotic or Biotic

Sign

Crack in trunk

Abiotic

Sign

Insect pitch tubes, frass (excrement)

Biotic

Sign

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