By Jeff Ray

DENTON, Texas (CBSDFW.COM) – It is estimated that ash trees make up approximately 3% to 5% of the total tree population across North Texas.

While that might seem like a lot, that translates to millions of trees.

Ash trees are usually found along the riverbanks and low laying areas here in Texas.

The bulk of their population in Dallas County for example is in the Trinity River basin.

Ash trees are not that popular urban planted tree.

For this story we visited a park in Denton that planted dozens of them along the edge of the park along the streets that line the park.

It is not recommended that you plant a single type of tree in this way; diversity is always a safer way to keep your canopy. Why? Because sometimes a certain species of tree will come under attack by a fungus or a bug.

That is what is happening to ash trees.

An invasive beetle from Asia called the Emerald Ash Borer (EAB) first showed up in Detroit years ago.

About three years ago it showed up in the Metroplex.

Emerald ash borer specimens. (Photo by Carl D. Walsh/Portland Portland Press Herald via Getty Images)

The beetle attacks healthy ash trees, laying eggs under the bark. The larvae hatches and starts eating the living tissue of the tree just under the bark. This slowly kills the tree as it cuts off the flow of nutrients. The beetle attack takes a couple of years, but the tops of the tree will die off first.

The tree can be saved with a professionally applied insecticide. It really must be injected into the tree; some homeowners try to drench the base of the tree but that has showed very little success.

The insecticide is also rather hazardous to handle so, please, use a professional. It is not exactly cheap, likely between $100 and $300 per treatment — depending on the diameter of the tree. The treatments will also have to be done every couple of years. But the cost is still much cheaper than having an arborist come remove the tree safely. Plus, there are possible energy savings to take in account if your Ash tree provides shade on your house.

Also, if the tree is putting shade on your house, there are cooling bills to consider.

It is recommended that municipalities take in inventory of their urban forest.

This is expensive but is important information not only in fighting EAB but also other tree issues like Oak Wilt.

Once a city knows where the ash trees are, they can start carefully monitoring set traps to find out if the beetle is in that area.

Then decisions have to be made on what trees to save and what trees to cut down.

Over the next couple of weeks Gardening 101 is going to concentrate on tree health.

We are going into a long dry period in the wake of the historic cold spell of the last February.

This is going to put more stress on trees already trying to recover from the extreme freeze.