Aphids, Friend or Foe?

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Are you finding ants on your aspen or cottonwood trees? Is there a sticky “sap-like” substance on your walkway, car or patio furniture? If these problems sound familiar, your trees are likely infested with aphids.

The following information is based on the Colorado State University Service in Action Sheet by Whittany Crenshaw, an Entimologist at Colorado State University.

Quick Facts
* Aphids occur on almost all types of trees and shrubs. They usually do not damage plants but the aphid honey dew can be an inconvenience when the sticky aphid excretion lands on cars and outdoor furniture.
* Problems most commonly occur in Summit and Eagle Counties when aphids produce leaf curls, on trees such as cottonwoods and aspen trees.
* Check for natural enemies before treating with insecticides.
* Systemic insecticides are particularly effective when aphids have curled the leaves.
* Contact insecticides and soaps are useful when aphids are exposed on leaves.

Description
Aphids are small insects, typically less than 1/8 inch, although some may be almost 1/4 inch long. Colors range from bright orange or red to dull gray. One common group, woolly aphids, produces an abundance of flossy, waxy threads that cover their bodies. Winged and wingless forms can be produced by all Colorado aphid species.

Aphids feed on plants by sucking plant sap from the leaves, twigs or stems. When abundant, aphids remove large quantities of sap, reducing plant growth and vigor. Aphids feeding on developing leaves also can produce leaf curl injuries.

Most aphids excrete large quantities of a sweet, sticky substance called honeydew. At times, excessive honeydew dropping from trees can be an extreme nuisance. Also, sooty mold fungus may grow on the honeydew, producing a gray, unattractive covering of the leaves. Sooty mold is not damaging to the trees except when it covers leaves and temporarily reduces photosynthesis.

Ants often are attracted to honeydew and feed on it. Ants may even tend aphids and other honeydew-producing insects (certain scales, leafhoppers, treehoppers), protecting them from natural enemies such as lady beetles and lacewings. Often the presence of ants crawling up trees or on foliage indicates that large numbers of aphids or other honeydew producers also are on the plants.

Control
Many kinds of insects naturally prey upon aphids. Most common are various species of lady beetles (ladybugs), green lacewings, syrphid flies and small parasitic wasps. Under many conditions, these beneficial insects provide effective control of aphids. Before applying any insecticide, check the plants to make sure these natural controls are not already reducing aphid numbers. Sometimes ants interfere with these natural controls. Excluding ants with sprays, sticky bands, etc., can allow biological controls to be effective.

When natural enemies are not abundant enough to provide aphid control, insecticides sometimes are needed to prevent plant injury. For most aphid problems, particularly those associated with leaf curls, insecticides that move systemically within the leaf or plant provide the best control. The most common systemic insecticide available to homeowners is Orthene (acephate) and Cygon (dimethoate), which is available as a spray for use on evergreens. In addition, DiSyston is a systemic insecticide sold in granular form, or as a plant food mixture that can be mixed with soil and picked up by plant roots.

Some plants may be injured by certain systemic insecticides. Carefully read and follow all label directions. None of the systemic insecticides available to homeowners can be legally used on food crops.

Contact insecticides that do not move systemically in plants are useful for aphid control where the insects are exposed on the plants. Contact insecticides for aphid control include Malathion, Diazinon and Dursban. Plant coverage must be thorough when using contact insecticides. Diazinon is extremely hazardous to birds, so use with extra caution on plants frequented by birds for nesting or feeding. Sevin (carbaryl) is effective against most woolly aphids found on evergreens, but has limited effect on most other aphid species.

On tolerant plants, insecticidal soaps can provide aphid control. Soaps typically have a low residual and require several applications during a season. Always test soap or detergent on a small area of the plant because these products may injure plants.

Aphid problems originating from eggs that accumulate over wintertime can be controlled with dormant oils.

Where high water pressure is available, infested plants may be hosed with water to reduce aphid numbers. This also removes recently deposited honeydew.

Pine Beetle Protection 101

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Reserved for MPB info

Dealing with Drought Stress

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Typically, cold snowy winters and cool, relatively dry summers are the normal for weather patterns in Summit and Eagle Counties; however, the weather over the last few years has not been exactly typical. The winter snowfall has been below normal and the summers seem a bit warmer than usual. Most of our summer rainstorms, when we get them, have been fast and furious rather than a slow rain that can soak into the soil.

This drought-like weather pattern has raised havoc on many of our trees. Trees of all ages and histories are showing signs of drought injury. In fact, symptoms of drought injury to trees can be sudden or take up to two years to be revealed!

Typically, leaves may wilt and scorch, or fall early in the season and make the tree appear thin and sickly. Evergreen trees may exhibit drought stress as brown needles at their tops and ends of lateral branches. Often times, drought stress may not kill a tree outright, but set it up for more serious secondary insect and disease infestations. So, what can we do to preserve the health and value of the trees in our landscape when water restrictions are commonplace and conservation of this precious resource is critical?

Following these tree maintenance procedures during drought periods can significantly increase a tree’s chance of making it through low moisture times and allowing it to continue to be a valuable part of the landscape for years to come.

For existing plant materials requiring regular watering, remove water-loving bluegrass from the base of the tree or shrub out to its dripline. Removal can be done with non-selective herbicides (such as Round-Up) or the grass can be mechanically removed. Be careful not to damage surface roots of the shrub or tree if mechanically removing the sod. Replace the grass with two to four inches of wood chip mulch. The mulch will not compete for water like the pre-existing grass. It will also keep the lawn mower and weed-eater at a distance from damaging tree bark and will insulate the soil from temperature extremes. Over time the mulch will break down adding nutrients to the soil. The decomposition can improve soil structure, aeration and water penetration. Most important, mulch helps retain moisture in the soil for longer periods between watering and rainfall.

Young or newly planted trees and shrubs require more frequent watering than mature, established trees. Drip irrigation systems are efficient at applying the proper amounts of moisture to newly planted trees and shrubs, while not wasting large amounts of water that above ground spray irrigation systems do. Watering every two to three days during our summer months is critical for new trees to establish. Be sure to frequently check soil moisture levels with a trowel or pointed tool and only apply water when soil conditions warrant.

Established and mature trees and shrubs need less frequent watering and can withstand drought conditions better than new plant material. However, it is important to add supplemental water to these plant materials as well, since they can be quite valuable specimens in the landscape and take longer for drought injury to appear. Apply water every three feet within the tree’s absorbing root zone, which generally extends from just within the tree’s canopy to beyond its dripline. Soaking the tree with drip system or manually by hose once a week during the summer months should be sufficient to maintain the tree’s health. Apply the moisture at a slow rate to allow deep soaking, and to avoid run-off, approximating about an inch of moisture per week. Check the soil moisture just like you would for the young tree.

Minimize fertilizer applications during time of drought, as these may stimulate too much top growth resulting in too much leaf area on the plant for the root system to maintain during periods of limited soil moisture. It is ok to use root-stimulating fertilizers or mycorrhizae inoculate that do not promote leaf growth. Properly prune trees and shrubs during time of drought to improve structure, limb stability and to remove dead and weakened branches. Leaving broken, dead, insect-infested or diseased branches can further weaken a tree during drought and set the tree up for deadly secondary insect and disease problems.

Follow these guidelines to help your trees through this period of drought. After all, trees are a renewable resource, but why wait to until they are sick to show them a little love?

Mountain Pine Beetle

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Mountain pine beetle, Dendroctonus ponderosae, is an insect native to the forests of western North America. Previously called the Black Hills beetle or Rocky Mountain pine beetle, periodic outbreaks of the insect can result in losses of millions of trees. Outbreaks develop irrespective of property lines, being equally evident in wilderness areas, mountain subdivisions, and back yards. Even windbreak or landscape pines many miles from the mountains can succumb to beetles imported in infested firewood.

If you think your pines are infested, we’re here to help.

Mountain pine beetles develop in pines, particularly ponderosa, lodgepole, Scots (Scotch), and limber pine. Bristlecone and pinyon pine are less commonly attached. During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease, or old age. However, as beetle populations increase, mountain pine beetle attacks may involve most trees in the outbreak area.

A related insect, the Douglas-fir beetle (Dendroctonus pseudotsugae), occasionally damages Douglas-fir. Most often, outbreaks are associated with previous injury by western spruce budworm. Spruce beetles (Dendroctonus rufipennis) are a pest of Engelmann and blue spruce in Colorado, and injured pines also can be attacked by the red turpentine beetle (Dendroctonus valens).

When To Check for Pine Beetle Infestation

The best time to check for Pine Beetle attack is in the fall or winter before the snow gets too deep. The spring is also effective because many of the infested trees have started to fade and are visible from a distance. Check for blobs of sap on the trunks of your trees. If you see “pitch tubes”, cut a piece of bark off and see if the wood under the bark is discolored bluish-gray. If so, the tree(s) need to be removed.

Signs and Symptoms of Mountain Pine Beetle Attack

* Popcorn-shaped masses of resin, called “pitch tubes,” on the trunk where beetle tunneling begins. Pitch tubes may be brown, pink or white in color.

* Dust in bark crevices and on the ground immediately adjacent to the tree base.

* Evidence of woodpecker feeding on trunk. Patches of bark are removed and bark flakes lie below the tree.

* Foliage turning yellowish to reddish throughout the entire tree crown. Usually occurs either to ten months after a successful pine beetle attack.

* Presence of live beetles (eggs, larvae, pupae, and/or adults) as well as galleries under the bark. This is the most certain indicator of infestation. A hatchet for removal of bark is needed to check trees correctly.

* Blue stained sapwood. Check at more than one point around the tree’s circumference.


Infested Trees

Once mountain pine beetles infest a tree, nothing practical can be done to save that particular tree. Under epidemic or outbreak conditions, enough beetles can emerge from an infested tree to kill about two same-sized trees the following year.

Ips and related beetles that emerge early in summer often are mistaken for mountain pine beetle, leading to early reports that “mountain pine beetle is flying.” Be sure to properly identify the beetles you find associated with your trees.

Trees from which mountain pine beetle have already emerged (look for numerous round, pitch-free exit holes in bark) do not need to be treated.

The direction and spread rate of a beetle infestation is impossible to predict. However, attacked trees usually are adjacent or near previously killed trees.

Western Balsam Fir Beetle

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The western balsam bark beetle is the most conspicuous of a complex of pests which are responsible for high amounts of tree mortality in sub-alpine fir stands throughout Colorado.

Hosts
Sub-alpine fir, Engelmann spruce, and Lodgepole pine

Damage
Low populations maintain themselves in trees weakened by old age and root disease, storm-damaged trees, or slash. During periods of drought or other environmental stress, infestations can build and spread to less-susceptible stands. Groups of 100 to 1,000 trees, generally of larger diameters, may be killed. An estimated 35 percent of sub-alpine fir mortality is due directly to attack by beetles.

Life history
The Western Balsam Fir Beetle probably has a 2-year life cycle in much of Summit and Eagle Counties. They likely overwinter as larvae under the bark the first year, continue development during spring and early summer, and overwinter the second year as nearly mature adults. Males bore into the phloem, excavate a nuptial chamber and mate with several females. Egg galleries radiate from the central nuptial chamber in a random pattern. Larvae extend their mines from the main egg galleries until freezing weather, then become dormant..

Identification
Unlike the mountain pine beetle that leaves a popcorn shaped pitch tube the Western Balsam Fir Beetles are identified by long dribbles of yellow pitch. , Entrance holes and boring dust on the bark may be visible. Attacked trees generally turn yellowish-red within a year. Adults are shiny, dark brown, cylindrical beetles ranging from 3.4 to 4.3 mm long. Their thorax is evenly convex above; their posterior is abruptly rounded and without spines. The front of their head is covered with distinct bristles. Females have a denser patch of these ‘hairs’ than do males.

Management
To keep beetle populations in control the best approach is to minimize broodwood by destroying slash and trees removed for construction. Weakened and beetle-infested trees or windthrown should be removed and the wood treated by peeling, chipping, burning or hauled to a safe location.

If you think that your Balsams are at risk of infestation, or are already hosting some critters, give us a call and we’ll do all we can to return your yard to its equilibrium.