Fall Tree and Pest Manual

Pests to look out for in the fall:

Fall webworm and orange-striped oakworm

Worms (aka caterpillars) are the larval stage of moths and butterflies that eat foliage. Depending on when they first appear, we classify them as early- or late-season defoliators. Late-season defoliators, like fall webworm and orange-striped oakworm, are less harmful than early-season defoliators since their host (the tree) has already made most of its food for the season.

Late-season defoliators typically first show up in late July and may last until early October. Generally, late-season defoliators are not treated, but there are some exceptions, including:

• Repeated and/or large defoliation events, which can have a significant effect on the tree’s long-term health.
• Nuisance situations where waste (poop) is excreted over a sidewalk, deck, pool, parking area, etc.

Cool season spider mites

Another type of pest you may see in the fall is the cool season spider mite. Cool season mites are tiny arachnids that feed on the sap in foliage. They’re most active in the cooler weather of spring and fall when daytime highs remain below 85℉.

Cool season mites are hard to see with the naked eye; you’re more likely to notice the damage their many tiny feeding spots cause. Foliage that’s normally green will look bronzed, yellow, and/or white. This type of damage is called stippling.

Heavily infested foliage can also become covered with an almost invisible webbing.

Are cool season mites a threat to your trees and shrubs? It depends. The good news is that spider mites have a lot of natural enemies that can usually keep the population in check. But if you find your infestation particularly heavy, a treatment could help.

Fall fertilization

Pale, yellow, and/or off-color leaves.

Leaves that are smaller than usual or changing color and dropping early.

Fewer flowers or fruit.

Slow growth or reduced overall vitality.

If you’ve noticed any of these issues with your tree, it may be nutrient deficient.

Depending on the species, trees need 16-19 essential elements to grow and function. But since most urban landscapes are nutrient deficient because of their highly altered soils, many trees are left without the nutrients they need. The nutrients trees could get from fallen leaves is often raked away, plus many trees have to compete for nutrients with turf.

That’s why most urban trees could benefit from supplemental fertilization. Fertilization restores missing nutrients to your soil to improve the health of your tree.

Root rehabilitation

Is the soil around your tree compacted? Soil compaction is pretty common in urban landscapes. In fact, it’s a top stressor for urban trees. Heavy machinery rolling through your yard, parking cars under your tree, or even years of walking through the same area can tamp down the soil around your trees.

Compacted soil makes life harder for your tree. Water and oxygen can’t penetrate overly compacted soil, and neither can any new roots your tree produces.

We offer different levels of root rehabilitation to restore pore space and add nutrients to the soil.

Root flare excavation

The root flare is the bottom part of your tree where the roots merge into the trunk. When it’s covered up by soil and/or mulch, moisture can get trapped against the bark and eventually waterlog it. Soil and/or mulch can also block the exchange of oxygen and carbon dioxide for the tree.

Root flares end up covered up for a variety of reasons. Sometimes trees are planted too deeply, and other times the tree just naturally settles deeper into its planting hole. Improper mulching or grade changes during construction projects can also leave your tree’s root flare covered up.

If you’ve noticed foliage yellowing, early leaf coloration and drop, or upper crown dieback, a buried root flare could be behind it all.

You can use a shovel to expose your tree’s root flare if it’s not buried too deeply, but be careful! Bark in the root flare area is delicate — you could inadvertently hurt your tree while trying to remove the soil or mulch around it.

It may be better to just leave it to our professionals. We have specialized equipment to safely expose root flares.

Spring fungal diseases you’ll want to protect against in the fall

Spring fungal diseases, like anthracnose and leaf spot, are spread and maintained via spores that over-winter on fallen foliage and other tree parts. As temps warm and moisture increases in spring, these spores serve to re-infect the new tree foliage as it begins to form.

When the infection is severe enough, the tree may lose its foliage prematurely, and when this happens repeatedly, the tree may not be able to make enough food for itself via photosynthesis.

Consequently, the tree’s long-term health may begin to suffer. In North Carolina, we often see this with cherry and dogwood trees.

When it comes to fungal infections, it’s all about prevention versus eradication. Treatment must begin and continue throughout the early spring vulnerability period when new foliage is being formed.

Unfortunately, we are often called later in the season, when it’s already too late to treat effectively. To be more confident in your treatment, schedule your spring fungicidal treatment(s) in the fall. We’ll get you on the calendar and be able to treat before it’s too late.