Fall Tree and Pest Manual

Fall is one of the best times to nourish and care for your trees! Our Fall Tree and Pest Manual will show you how.

Late summer and early fall are interesting seasons from a plant health care perspective. Some insects lay their eggs at this time of year, while others are just joining Tinder with big plans for the spring. During fall, we can handle both. In our fall tree and pest manual we’ll share what you may see on your trees in the fall versus what you won’t see in the fall, but should definitely care about in the fall.

What you may see in the fall: Fall webworm and orange-stripped 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-stripped 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 late Sept. Generally, late-season defoliators are not treated, but there are some exceptions.

  • Annual 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.
Fall Webworm Tree Bug

Here’s what you need to know about your treatment options for worms in your trees:

  • Foliar treatments take effect in 1-2 days, but typically only last 2-4 weeks. When applied early in the season, additional treatments may be needed for season-long control.
  • Soil-injected treatments take effect after 2-4 weeks, but last longer – typically 8 weeks or so.
  • Trunk-injected treatments take effect after 2-4 weeks and can provide control into the following season when applied late enough in the season.

What you won’t see in the fall, but should care about in the fall: Spring insects

Yes, we know it may sound odd, but late fall is a great time to treat for spring piercing-sucking insects. These are little pests like aphids, soft scales, lace bugs, and white flies that use their mouths to puncture your leaves and suck out their delicious, nutritious, plant juices. Importantly, for you, these pests can be plentiful, covering your foliage, branches, and/or trunk. They can also leave yellow or white spots on your leaves, cause wilting or branch decay, and reduce the growth of your trees. If you have an issue this year that you don’t want to repeat next year, treating for these pests in the late fall will prevent problems from occurring the following spring.

Here’s what you need to know about your fall treatment options to combat spring insects:

  • We will not treat the pests themselves during the dormant season after your tree has already lost its leaves.
  • Rather, we can apply a systemic soil treatment in the late fall, so the insecticide is loaded and ready to go.
  • That way, when spring arrives and new foliage is beginning to form, your tree’s roots can quickly pick the treatment up from the soil and distribute it throughout the trunk & crown for complete protection.

What you won’t see in the fall, but should care about in the fall: Spring fungal diseases

Spring fungal diseases, like anthracnose, are spread and maintained via spores that over-winter on fallen foliage and other tree parts. In spring, as temps warm and moisture increases, these spores serve to reinfect 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. In turn, 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 commence 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, fall is a great time to schedule your spring fungicidal treatment(s). We’ll get you on the calendar and be able to treat before it’s too late.

Here’s what you need to know about your treatment options for tree fungal diseases:

  • Reducing residual spore loads via sanitation is important. This means raking up infected foliage that has fallen and exists around the base the tree. It also means pruning out dead branches and limbs.
  • These actions will reduce the localized spore load and lessen the opportunity for spores to reinfect your tree in the spring. Note: If your trees are disease-free, leave as many leaves on the ground as you’re comfortable with. They’re good for fertilization!
  • Come spring, we can then apply foliar fungicides just prior to and while the new growth is forming to significantly reduce reinfection rates.
  • Both organic and traditional synthetic fungicidal treatments are available.

But wait, there’s more on tree bugs and pests!

While we have a lot of information on this page and even more on our I Have Tree Bugs! page, we also keep our readers abreast of plant healthcare issues through our regularly updated blog. Feel free to search the blog at any time but below is a quick reference of blog topics on tree diseases and pests for you.

Seasonal Advice for Healthy Trees

Preventative Treatments for Tree Health

Bug-specific Blog Posts

Tree- and Plant-specific Blog Posts

And all-around great DIY tree and landscape advice