SHOULD WINTER DAMAGED EVERGREENS BE PRUNED NOW?

No doubt you have been noticing brown, dead patches in your evergreens this spring. This is the plant’s response to the extremely harsh winter. Your first impulse may be to prune out the damaged foliage and dead twigs. This might seem to make perfect sense, but wait!

While the dead needles and leaves will not green up and they will drop off later in the season, there are buds on the twigs that might produce new foliage and twigs. If pruned too early in spring these buds will be removed, greatly affecting the plants’ recovery and appearance.

Because of the very cold and windy winter, some of the buds may have been killed as well. However, we won’t know what parts of the plants have survived until mid-late May.

So, put down the pruners and be patient. Let’s see what will grow on your damaged evergreens and then remove just the dead portions of your damaged tree or shrub.

 Evergreen tree showing signs of winter burn.

Boxwood shrub leaves turned yellow above the snow line from winter burn.

GYPSY MOTHS IN LAPEER, MI

Occasional flare-ups of gypsy moth populations are not uncommon around Lapeer due to the number of trees and the species of trees found in the area. We do occasionally receive calls from homeowners that think they have gypsy moth, but it turns out to be less damaging caterpillars – usually eastern tent caterpillars or forest tent caterpillars.

Gypsy moth caterpillars have five rows of blue dots followed by six rows of red dots along its back, front to rear. The eastern tent caterpillar has a white stripe running the length of its back. The forest tent caterpillar has a series of “keyhole” shaped, yellowish dots running the length of its back. Each of these different caterpillar species get rather large and are hairy.

Here’s what to do to determine if you actually have gypsy moth caterpillars and what actions you can take if it turns out you do have gypsy moth caterpillars on your trees.

Do you know what kind of trees you have on your property?

It’s less likely you have gypsy moth caterpillars on your trees if you don’t have any trees they like to eat. Gypsy moth prefers to feed on oak, aspen (poplar), birch, crabapple and willow trees. We have found them feeding on other tree species (even spruce trees), but this is only when their population is at its peak.

Where can you find gypsy moth egg masses?

Look on the underside of tree branches, on tree trunks, under house overhangs, or the underside of bird baths. Almost any object in your yard could have gypsy moth eggs masses on it. Gypsy moth eggs masses are gold, brown, or tan colored, 1 to 1 1/2 inches long, and oval shaped. The egg masses are flattened against whatever they are laid on and are covered with fine hairs.

What can be done to control gypsy moth caterpillars?

In Lapeer, gypsy moth caterpillars start hatching in mid-May with peak feeding injury occurring in mid to late June. The safest treatment for gypsy moth caterpillars is to spray infested trees with Bacillus thuringiensis (B.t) when the caterpillars are small. However, B.t. is not effective for control of gypsy moth when the caterpillars are greater than one half inch long.

Controlling larger gypsy moth caterpillars can be done with any one of several registered traditional insecticides labeled for control of gypsy moths. Most insecticides labeled for control of gypsy moth will work both on contact and leave a residual on the foliage that will control caterpillars that show up after the tree spraying is done.

What if defoliation from gypsy moth caterpillars has already occurred?

Gypsy moth caterpillars are heavy feeders and can consume 100% of the foliage on a tree. A couple years of heavy defoliation can kill even a mature tree in your landscape. All trees infested with gypsy moth caterpillars should be given adequate water and fertilizer to help them recover. Any amount of defoliation from gypsy moth caterpillars may cause some branch dieback, so pruning may also be necessary.

EASTERN TENT CATERPILLARS

The silken nests of eastern tent caterpillars will be starting to appear in the Shelby Township area soon. The eastern tent caterpillar is partial to cherry, apple, and crabapple trees, but they’re not opposed to infesting your peach, plum and pear trees, as well.

Eastern Tent Caterpillar Damage

The eastern tent caterpillar can potentially defoliate a small to mid size tree.

Identification

The silk nest is a dead giveaway that you have eastern tent caterpillars in your tree. As soon as the young caterpillars hatch from the egg mass they will look for the nearest suitable crotch in the tree (branch or main stem) and begin construction of a nest. The eastern tent caterpillar nest is built in layers. With each succeeding layer the nest grows in size. Depending upon the number of individuals in the colony, a mature eastern tent caterpillar nest may range in size from a baseball to a softball. The nest is home base for the colony. They move in and out of the nest several times throughout the course of a day.

Homeowners in Shelby Twp. occasionally confuse the eastern tent caterpillar with the gypsy moth caterpillar. Both grow to be big hairy caterpillars and both occur in the spring. However, in Shelby Twp. the eastern tent caterpillar hatches nearly a month before the gypsy moth. The eastern tent caterpillar also looks different from the gypsy moth. Where the gypsy moth has a series of blue dots followed by red dots on its back, the eastern tent caterpillar has a white stripe down the middle of its back.

The eastern tent caterpillar does not appear in your tree out of the blue. The egg mass was probably there since the previous summer (July). Once the leaves fall, the egg mass is easier to spot. It looks like a dark swelling of a twig or small branch. The eggs are covered with an excreted fluid that hardens and takes on the appearance of a shiny dark varnish. The caterpillars hatch early in the spring because the embryo is completely developed by first frost. An egg mass will contain 150 to 350 eggs.

There are several means available to control eastern tent caterpillar.

Cultural Control

As soon as the leaves fall, check susceptible tree species in your landscape. Pay special attention to any trees that had a nest the previous spring. The egg masses can be removed by hand. This control method is particularly effective on your smaller trees, which can be completely examined. You can either scrape off the egg masses or clip off the branch if it’s not going to affect the appearance of the tree.

If you see tents being formed in the spring you can remove the actual nest. Wind up the nest and caterpillars on a stick and dispose of them in your garbage.

Biological Control

There are several natural enemies that attack and thrive on eastern tent caterpillars in Shelby Township. In particular, the northern oriole thinks it has died and gone to heaven when they find a tree with eastern tent caterpillars. Also attacking eastern tent caterpillars is a parasitic fly which looks like an overgrown house fly. The fly maggot burrows into the caterpillar, but doesn’t finish it off until it pupates. There are also other birds, beetles and wasps that dine on this caterpillar.

Chemical Control

Tree spraying options include both organic and traditional insecticides. If the caterpillars are less than 1/2 inch in length a Bacillus thuringiensis (B.t) spray can be applied. For larger caterpillars, there are several insecticides labeled for control of eastern tent caterpillars.

SWISS NEEDLECAST OF DOUGLAS-FIR

Douglas-fir trees are susceptible to two needlecast diseases, Swiss Needlecast and Rhabdocline. The more common of these two diseases we see in southeast Michigan is Swiss Needlecast.

Douglas-fir needles infected with Swiss Needlecast will show a yellowing and browning of the tips in the spring and summer but never any mottling. Needles are cast one or two years after infection during the late fall and winter. In severe infections of Swiss Needlecast only the current year’s needles may remain on the tree.

To confirm that Swiss needlecast has infected your tree examine the undersides of the needles in the spring. Look for two rows of small black fruiting bodies, one on each side of the mid-rib of the needle. The black fruiting bodies protrude from the air exchange holes (stomata), which normally appear as small white dots. Spores from Swiss Needlecast are mostly moved by rain splash or irrigation systems. Thus, Swiss Needlecast disease usually spreads only to nearby trees. New needles are susceptible to Swiss Needlecast infection when all buds have broken and needles are elongating.

Cultural Control of Swiss Needlecast

Weed control under Douglas-fir trees and adequate plant spacing allow better air circulation and thus the drying of rain and dew moistened needles. Such practices can have a major impact on the severity of this disease because Swiss Needlecast primarily affects the lower branches and infection depends on prolonged periods of needle wetness.

Chemical Control of Swiss Needlecast

Several fungicides are registered for the control of Swiss Needlecast. Infection usually begins in late spring and continues into the early summer. Fungicide applications should be applied when new shoots are 1/2 to 2 inches long.

Depending on general weather conditions in the spring two or three fungicide applications should be sufficient to control Swiss Needlecast.

BOXELDER BUGS IN THE HOME

What's 12.5 millimeters long with a dark brown or black coloration relieved by red wing veins and markings on the abdomen while its nymphs are bright red? This bug releases a pungent and bad tasting compound upon being disturbed to discourage predation.  You guessed it, the boxelder bug. Scientist say these annoying pests are found primarily on boxelder trees but if your home is anything like mine they seem to migrate on the outside of your house or even worse, in your home!

How do you get control of these bugs that seem to never go away in the spring and summer time? I have looked for home remedies on pinterest, facebook, and google but always seem to come up short. Sure, these home remedies will stop the problem for a couple of days but this is something you want to stop long term. Boxelder bugs are attracted to "female" boxelder trees, maple trees, and ash trees. Removing these tree species from your property is one fix this nasty problem. Only issue with this is the hassle of doing this work on your own with the busy lifestyles we all encounter day to day. Plus, the trees where the boxelder bugs are coming from might not even be on your property.

Did you know that 90% of all insects that get into your home come from outside? Nine times out of 10 the only way to get rid of these bugs and keep them away would be to get the perimeter of your home sprayed. A perimeter pest control program creates a barrier around your home that keeps invading insects outside. Our perimeter pest control takes only five treatments starting in the spring with follow up treatments once every 4-6 weeks for ongoing insect control. Not only will this program take care of boxelder bugs it will also stop spiders, roaches, fleas, ants, ticks, crickets, bees, hornets, and earwigs from coming into your house. 

Take care of this problem before it happens. Call Owen Tree Service today to set up your perimeter pest control treatments.