How Are Spring Pests Affecting Trees In Denver?

Denver is starting to thaw out and spring is upon us! That means getting out and prepping your landscape for spring and summer. You’re itching to get outdoors and enjoy all your favorite fair weather activities. Reading on the front porch, grilling out, and gardening are at the top of your list.

We aren’t the only ones ready to come out of hibernation mode. Spring pests are on the verge of waking and becoming active. There’s a small window of time to act and take preventative measures to control these pests before they invade.

Japanese beetles and aphids both have established a strong presence and population in Denver. They are negatively affecting Denver trees by attacking leaves and damaging the health of the overall plant.

Luckily, there are safe and effective treatments to manage and control these spring pests. Don’t let the Japanese beetles and aphids ruin the quality outdoor time you crave for your spring and summer. Act now and contact our arborists to find out how to protect your trees before the spring pests become active. Stop infestation before it starts!

Japanese Beetles Affect Linden Trees

Japanese beetles were first recognized in Denver in 2006. Since then the beetle infestation has grown enormously, becoming a fixture in the Colorado landscape. Despite the county’s best efforts, the Japanese beetle population continues to grow and spread each year. Japanese beetles are easily recognizable by their metallic green shell. The beetles may look pretty, but they are considered one of the most relentlessly destructive urban pests in the US!

Here are some quick facts on the Japanese beetle from the Colorado State University Extension:

  • Japanese beetle adults chew flower blossoms and leaves of many commonly grown plants.
  • Japanese beetle larvae are a type of white grub that feeds on the roots of grasses.
  • Adults are best controlled by handpicking or by use of certain insecticide sprays.
  • Japanese beetle traps can capture many adults, but do not reduce damage to nearby plants.
  • Japanese beetle larvae can be controlled with certain insecticides or by insect parasitic nematodes.

There are 300 plant varieties that the beetles crave and prey on, but lindens are on the top of their list! What does it look like when a linden is infested by Japanese beetles? Here are some classic signs:

  • Skeletion-like leaves: Japanese beetles devour the tender parts of the leaves, leaving veins. The result is severely damaged, lace-like leaves. They do not fall off, instead the leaves hang on the branch until they dry out.
  • Scorched appearance: Trees with a very severe infestation can develop a scorched look to the bark and leaves.
  • Beetle activity: Japanese beetles are not sneaky! They can easily be spotted flying from tree to shrub, feasting on leaves. If you have a Japanese beetle infestation, you will see them be especially active on warm sunny days.

Aphids Affect Ash, Apple, and Crabapple Trees

There are over 350 species of aphids! They are tiny, only a few millimeters long, and range in color from light yellow to dark brown. Many are harmless, but the rosy apple aphid, woolly apple aphid, and leaf curl ash aphid are plaguing Denver’s trees. Ash, Apple, and Crabapple trees are endangered by these pests. Not only do aphids wreak havoc on the trees they infest, but they also attract other harmful pests!

Aphids harm trees by sucking sap from them as they feed. According to the Colorado State University Extension, when the number of aphids on a plant are very high for an extended period, their feeding can cause wilting and sometimes even dieback of shoots and buds. Some aphids can cause leaf curling when the insect infests emerging leaves.

Noticing an unwanted increase in other insects such as wasps, ants, or flies in your yard? Aphids produce and excrete honeydew. This sticky residue left behind by the aphids will cover leaves, branches, and even sidewalks under the trees that they infest. The honeydew attracts other pests, creating further problems in your landscape. As it ages, the honeydew grows gray dusty mold. This is unattractive feature is a red flag of an aphid infestation.

Signs of an aphid infestation:

  • Woolly aphids obscure their body by covering themselves with waxy threads. Look for limbs covered in a waxy film. You will probably find a cluster of aphids there!
  • Sticky leaves or stems is a sign of honeydew left behind by aphids.
  • Fungal growth is a result of aphid honeydew production.
  • Leaves will begin yellow, look misshapen, curling, or stunted.

Soil injection insecticides are very effective for fighting aphid infestation. Once the insecticide has moved within the plant these treatments will usually be able to kill aphids – and other susceptible insects – for several weeks, perhaps a couple of months. This long persistence can provide very good aphid control.

Lepitect Treatment

Lepitect is an environmentally safe soil injection insecticide. It is a unique solution that provides rapid results, delivering systemic control of many key shade tree pests. It is highly effective tool for management of Japanese beetles and aphids. One application of Lepitect will give 30 days of efficacy for insect larvae.

Lepitect Comes In Two Forms:

  • The soil injected form of Lepitect treats 25 inches of tree diameter (DBH) at the high rate and 50 inches at the low rate.
  • The tree injected form of Lepitect treats 71 inches of diameter (DBH).

How Lepitect Works

Soil injection of Lepitect involves placing chemicals in liquid form near the roots in the soil for root uptake. The chemicals are water-soluble, similar to other injection methods. For best results, Lepitect will be applied to soil that is moist, but not soaked.

With soil injection, also called the soil drench method, the insecticide is mixed in water and simply poured on the soil near the tree’s root crown. For this to work mulch or other surface organic matter is has to be pulled back. It is important that the chemical is poured directly on the soil. Afterwards the mulch can be replaced.

Soil injection methods vary somewhat, but typical recommendations are to inject chemicals 2–4 inches deep with a high pressure injector either within 18 inches of the trunk or on a grid. The amount of Lepitect to be applied depends on trunk diameter, and diameters are added if multiple trees are being treated in an area.

Trunk injection is another application option. Injection of Lepitect into a tree trunk directly applies concentrated systemic pesticides into a tree’s vascular tissues for faster translocation. Trunk injection has the same benefits as soil injection, in that the pesticide quickly enters the tree’s vascular system. Both applications of Lepitect are particularly effective in controlling some of the most troublesome insect pests, like Japanese Beetles and Aphids.

Here are details on how Lepitect is typically applied:

  • Application Method: Pull back landscape mulch, landscape fabric and surface organic matter prior to making soil applications to ensure solution is delivered to the mineral soil. Measure the diameter of the tree at breast height (DBH), 4’6” above the soil line. For multi-stemmed trees and shrubs, use the cumulative diameter of individual stems at soil line instead of DBH.
  • Application Timing: Make applications to actively growing plants just prior to or when insects first appear. Repeat applications every 2 weeks as needed.

Advantages of Trunk and Soil Injection Lepitect

Some pesticides and insecticides can be dangerous to birds, other insects, and nearby plants if they enter water runoff. You breath easy and feel confident when you choose Lepitect to manage pests in your lawn. It is safe and environmentally friendly!

Environmentally conscientious advantages of trunk and soil injection Lepitect:

  • Little, if any pesticide is wasted to drift or runoff when applied because it can be injected precisely to where it is needed in the tree.
  • Can apply Lepitect with trunk or soil injection during windy and rainy weather because there is no drift or runoff.
  • Trunk injections may be used on sites where soil treatments may not be practical, effective, or appropriate, including trees growing on excessively wet, sandy, compacted, or restricted-soil environments.
  • There is little non-target organism exposure; therefore, it is safe in environmentally-sensitive areas. Your nearby shrubs and plants will not be affected.
  • Injection methods for treating some of Denver’s troublesome pests, such as Japanese beetles and aphids, can be particularly useful.
  • Trees are not wounded during Lepitect soil injection applications.
  • The soil injection and trunk injection methods require very few tools and can be completed quickly.

Spending time in your outdoor space is precious during the spring and summer months. Your beautiful trees and shrubs create the serene atmosphere for all your favorite activities. Protect your lawn and landscape from spring pests with environmentally safe Lepitect.

Our certified arborists can complete a quick and free consultation, helping you get on the path to a pest-free spring and summer! Stop spring pests in their tracks. Contact us at Fielding Tree & Shrub Care for more information on this simple, safe, and effective solution!