Taking Care of Our Trees

As we welcome the spring weather, we also welcome the new leaves budding out and the daffodils and tulips emerging from the ground.

The City of Madison is a city that values and protects its trees. We provide over 96,000 street trees throughout the city. Trees provide many benefits including shade, lower temperatures, reducing cooling costs in the summer, and improved air and water quality. We also love the habitat for birds, wildlife, and the beauty they bring to our neighborhoods.

New trees require special care in their early development, and we rely on residents to care for the terrace tree at your property. Watering the new tree will help it grow and continue providing benefits for years to come. It may require up to 10 gallons of water every week, depending on rainfall. The soil should be moist, but not saturated. 

Mulch provides a good weed barrier and helps retain soil moisture. Add a little mulch each spring or fall to maintain a depth of 3-4 inches. Leave space next to the tree trunk. The mulch should not touch the trunk.

Avoid damaging the tree with lawnmowers, bicycle locks, and string trimmers. Please report any vehicle or vandalism damage to the Forestry office.

Avoid using weed killer near the new tree. Fertilizer is unnecessary the first two years. 

If the tree is staked, a Forestry crew will return to remove the stakes. Staking is necessary for one complete growing season.

As the tree matures City of Madison Forestry is responsible for pruning and will replace the tree if it dies.

Spongy Moth

You may have heard lately about a predator known as the spongy moth. This pest was formerly known as the gypsy month. In 2023, a combination of environmental factors created opportune conditions for the caterpillar/moth. Those environmental factors came at a time when there was a population spike in this pest. Every 10 to 15 years there is a boom in the spongy moth population.

The moths are only presenting in a certain part of the City right now, so most residents don’t have to be on the look out for them. Two areas on the west side, the southern portion of the Glen Oak Hills Park and the Kenosha Greenway will be treated with a spray to protect these public trees from the spongy moth caterpillar. The tentative dates for the application are Wednesday, May 1 and Thursday, May 2. The City website will have details and more information.

The spray will be applied from the ground into the tree canopy by certified arborists. They will be utilizing lifts as well, which may cause the temporary closure of S. and N. Kenosha Drive when the application is occurring. These areas were found to have a high concentration of egg masses in 2023, so they were identified as areas that could see another spike in the population in 2024 if environmental conditions favored another spike.

Spongy moths do better in warm, dry conditions – so if we have another warm, dry spring and summer in 2024, we could be in for another high spongy moth year.

In its caterpillar form, it can eat a whole lot of the leaves off a tree. This is called defoliation, and it is a stressor for trees that can lead to problems. Plus, the caterpillars can cause an itchy rash in some people – so it is best not to touch the caterpillars directly.

The defoliation is troubling to see, especially when its beautiful mature oaks and other beloved trees when they go from full canopies to losing so many leaves to these ravenous invasive caterpillars. Mature trees will rebound with new leaves to replace the ones lost to the caterpillars. But that defoliation is a stressor. Trees need a lot of energy to produce more leaves.

If you stack the stress of needing to flush new leaves on top of drought conditions and other issues, like problems from climate change or other pests – it becomes more worrisome about the health of the tree. And if the tree has to bounce back from this cycle again and again it becomes harder each time to recover.

Imagine it like a person being sick. For a person to fully recover, it's best for them to be well rested and have plenty to drink – "push the fluids" as the doctors always say. And recovery also takes time.

Same is true with trees. Help them avoid stress, and keep them watered.