A Day in the Life of an Arboreal Detective

Sometimes I feel like a detective while reading the description for my next arborist appointment. As soon as I get out of my car I start to gather clues. Most every tree or property I inspect daily are full of problems that need to be identified and hopefully solved. Here are 5 examples of what I have seen in the past two weeks…

My Pine Tree has Borers

• I get this call a lot. My first reaction is to inspect the tree canopy to look for dieback or discoloration.  Then I examine the holes and look for frass or a pitch tube coming out of the trunk of the tree. If it were a borer or bark beetle here in Richmond, it would likely be a turpentine beetle or pine bark beetle; however, 90-95% of the time the holes are actually caused by a woodpecker, not an insect. Below top is a turpentine beetle pitch tube and below are woodpecker holes in a pine tree.

My Oak Tree Has Curled Leaves 

• A client recently called and told me that the white oak tree in her front yard had leaves that were curled and misshapen. My first thought was jumping oak leaf gall or possibly early signs of anthracnose. But when I looked harder at the tree it appeared it might be herbicide damage. She said she or her lawn crew hadn’t sprayed her lawn. I looked across the road and saw a brown agricultural field.  I asked if she remembered anyone spraying across the street. She said one month ago the farm across the street got sprayed.  She was interested in the large machine spraying chemicals so she took a picture.  I looked up the weather for the day and time she took the picture and saw that the wind was 6 mph with gusts up to 12 mph. I recommended the client to reach out to the Farm or Department of Agriculture and Consumer Services to investigate to see what chemical was used to see if it could be a problem for her tree.  She had no idea that the chemical sprayed in another property or across the street could possibly travel to her property. There’s a name for that: chemical trespassing.

The Leaves on my Holly Tree are Black

• In the spring, on most holly trees I see the wonderful lime green growth that has already begun. Sometimes, as I walk closer to the tree, I can see the older leaves and branches of the tree are black. I know from experience there are a few different types of scale from insects that suck on the leaves of a holly and excrete honeydew (insect poop) everywhere.  The honeydew is sticky and high in sugar, and this attracts a fungus called sooty mold. Almost every holly tree in Richmond seems to have this ecology of insects and fungus. Trees/shrubs that are treated for the insect eventually clear up the fungus, but from my experience as soon as someone stops spraying, the insects and sooty mold come back.

The Trunk of my Tree is Diseased and Black

• Similar to the above, the black on the trunk of a tree is sooty mold.  But an arborist has to determine what’s causing it. Sometimes we help decide by the species of tree it is. For example, if the sooty mold is on a crepe myrtle, I’d guess aphids. Red maple I’d guess aphids or gloomy scale. And sugar maple, I’d guess woodpeckers. 

My Tree is Dropping Sticky Sap on my Deck

• This is not a new one to me. I went into this recent call thinking it was probably a willow oak with lecanium scale or a crepe myrtle tree with aphids. But when I showed up to this house, I saw a white oak tree and jumping oak leaf gall all over the leaves and deck, so my first thought was it must be the jumping oak leaf gall. Then I remembered there’s no way the gall would or could cause the sap to fall from the tree. I looked closer and couldn’t see any scale large enough to ID from the ground.  I went back to my car and grabbed my tools and clipped the end of a branch from the tree. The tops of the leaves were sticky, too, and as I looked more closely, I saw the jumping oak leaf gall but also a group of aphids crawling around on the oak leaves. Was I worried about the aphids on this tree? No, what I assumed, and I am pretty sure will happen, is we’ll see beneficial insects like lady beetles moving in to attack and eat the aphids. My recommendation to the homeowner was to clean off the deck before the sooty mold starts to grow.