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Learning Center - Metropolitan Forestry Services

Image of a backyard all sorts of different large trees.

We follow closely what goes on in our landscapes - here are some of the things we are seeing.

Do you know what kind of trees, shrubs, and plants you have in your yard? If you don’t, then you may not be aware of the kinds of insects and disease that can invade your property.

MFS has prepared information to better educate our staff and clients.

"Thank you so much for all the information you provide – the watering information, the emails and the flier. I read it all and have learned so much."

– Cynthia K.

Browse any of the topics below.

Don’t see what you’re looking for? Let us know!



Why are my tree’s leaves turning yellow?

Many tree species are not adapted to our alkaline clay soils, which can limit access to certain nutrients in the soil, especially iron and manganese. The yellowing leaves may indicate that your tree has chlorosis. Common trees that are affected include pin oak, red maple, white oak, river birch, tulip tree, sweet gum, bald cypress, magnolia, and white pine.

Why is half of my tree dead, when the rest of it looks healthy?

Trees are great at moving water and nutrients up and down the trunk, but have difficulty moving them around the trunk. Dieback on one side can indicate root damage on that side, such as from a girdling root, or damage from trenching, compaction, soil grade changes, or construction.

When should my trees be pruned?

It is best to prune most trees in winter when they are dormant. Trees should be pruned at times during which their most damaging pests and diseases are least active in order to decrease the chance of infection or infestation. Many flowering trees, however, can be pruned at specific times of the year to affect flower production.

When is the best time to plant?

When the ground is not frozen and the temperatures are mild. In Missouri, late fall and early spring are common planting times. You can plant throughout the growing season, but planting during the summer can increase stress and require more watering and care from the homeowner.

Why should I mulch my trees?

Properly mulching your trees is one of the best ways to improve their long-term health. Mulch provides many benefits: it insulates the soil from extreme temperatures, retains water during drought, suppresses weeds that could compete for water and nutrients, and reduces soil compaction and lawnmower damage.

How deep should my mulch be?

Different plants prefer different amounts of mulch, but usually 2-3 inches deep. Another factor to consider is the width of your mulch ring; trees usually have roots that extend beyond the reach of the longest branches, and can benefit from mulch anywhere under the canopy. The mulch should not piled against the trunk (like a volcano), as this can introduce pests and diseases that promote decay. Instead, create an open ring around the trunk (like a donut-shape), then lay a layer of mulch extending outward.

Will the vines on my tree hurt it in any way?

Vines can damage trees in several ways. They compete for water and nutrients in the soil. They can hold moisture against the trunk, making it more susceptible to decay. Also, insects and animals can use them as cover and habitat, their activities damaging the tree. They can shade out the leaves of the tree, and eventually add enough weight and wind resistance to make your tree more hazardous in storms.

Should I top my tree to help reduce weight?

Topping a tree refers to removing the entire top, or drastically reducing many large branches or trunks to decrease the size of the tree. It is extremely stressful to the tree and is almost never the best option. Removing so much of a tree at once reduces its ability to grow and restructure itself. New limbs that emerge from topping cuts are often fast-growing and weakly-attached, making the tree more hazardous in the future.

Can I use fertilizer spikes from the garden center?

Spikes are not an ideal way to fertilize your trees. They contain a small amount of fertilizer that is released quickly and shallowly in the soil. In contrast, deep-root fertilization provides a full, slow-release dose, is long-acting, and penetrates the soil deep enough to reach most of the root system.

Do trees have taproots?

Most trees begin growing with an anchoring taproot, but as it ages, lateral roots grow, originating near the top of the taproot – these lateral roots are responsible for supporting the vast majority of the active root system and anchoring the tree; 80-90% of a tree’s root system exists in the top 12-18 inches of the soil. The original taproot may be eaten away by soil fauna or rot away.

How often should I fertilize?

It depends on the tree and condition, but typically every other year. A tree in rich, healthy forest soil may never need to be fertilized, while the same tree may need to be fertilized every year if it’s in poor soil and surrounded by pavement.

Which trees are good for screening?

Hedge maple, hornbeam, and many evergreens (arborvitae, pine, yew, spruce) are all good choices for a visual screen.

Which trees do well in wetter areas?

Baldcypress, dawn redwood, swamp white oak, willow oak, river birch, and blackgum can all handle wet areas.

Which trees do well in dry, rocky areas?

Post oak, white oak, persimmon, chokecherry, and hoptree can all handle dry, rocky areas.

Which trees have the best fall color?

There are many options for vibrant red, orange, yellow, or bronze-purple fall color, especially maples, many oaks (swamp white oak, red oak, chinkapin oak, swamp chestnut oak), sweetgum, serviceberry, ginkgo, zelkova, linden, blackgum, crabapple, and baldcypress.

Which trees are fast-growing?

Tuliptree, many oaks (northern red oak, swamp white oak, willow oak, swamp chestnut oak), red and sugar maples, hybrid elms, and arborvitae are all relatively fast growers.

I planted all of my trees at the same time, so why are some growing faster than others?

Small differences in sunlight, moisture, soil texture, and nutrient levels can cause the same tree species to grow at different rates.

Why is my blue spruce dying?

Several fungal diseases have been affecting our spruce trees in recent years. One of our ISA Certified Arborists can collect a tissue sample to determine the exact species/ disease and help you develop a treatment plan.

My burning bushes are turning brown and are covered in webs. What happened?

The most likely culprit is spider mites. Spider mites can reproduce very quickly and impact a wide variety of plants. There are several treatment options available. Contact us and we’ll help you come up with a treatment plan.

How old is my tree?

The short answer is that you can’t tell just by looking at it.

The long answer is that trees and animals grow in different ways.  Animals usually grow quickly at the beginning, and level off as they reach maturity. Some animals, such as many fish, can continue growing at a linear rate indefinitely, and you can make a rough guess at their age based on their size.

Trees are entirely different. They usually grow slowly when first planted, and can put on exponentially more growth each year as they get larger and put out more leaves. The largest trees can gain hundreds of pounds a year! Their growth rate is dependent on both species and site conditions. Fast-growing trees in the tropics can reach 100 feet tall in just a few decades, while the oldest trees in the world (bristlecone pines) are often less than 20 feet tall. The only way to accurately age a tree is to count the rings after it is cut.

Is my tree getting enough water?

Most established shade trees prefer about one inch of water per week on average. They prefer deeper, less frequent watering compared to turf grasses.

Our goal is to provide you with the best possible service. If you are not satisfied with any treatment or completed job, we will resolve the situation to your satisfaction. We want to do our utmost to ensure your trees and shrubs are always 'green and growing'.