Hosts
Pecan, Hickory, Apple, Pear, Peach, Apricot, Plum, Cherry, Quince, Currant, Walnut, Poplar, Willow, Beech, Chestnut, Oak, Elm, Hackberry, Sycamore, Mountian Ash, Serviceberry, Hawthorn, Redbud, Maple, Horsechestnut, Linden, Persimmon, Boxelder. Maple, Apple, and Poplar are the preferred hosts, but many other trees are also readily attacked.

Range
A pest of many deciduous trees from Mexico throughout the United States into Canada(Brooks 1919a, USDA FA 1985)

Description
Adult: Broad, oval, flattened beetle about 7 to 16mm long(Brooks, Moznette and others 1931). Metallic hued and indistinctly marked with dull gray spots and irregular bands. Underside coppery bronze and beneath the wings metallic greenish blue.

Egg
Pale yellow, flattened, disk-like, wrinkled, and about 1.5mm in diameter. Firmly attached to bark by their flat surfaces.

Larva
Yellowish white, legless, and about 25mm long fully grown. Three thoracic segments much broadened and compressed, giving larva apperance of having large flattened head, which accounts for its name. Within galleries, larvea nearly always assume shape of a horseshoe.

Pupa
Somewhat yellower than larva; resembles adult; 7 to 19mm long.

Biology
Adults appear from March to November but are most abundant during May(Fenton 1942, Moznette and others 1931). Beetles, most active in full sunlight, run rapidly and take flight quickly when disturbed. On hot, clear days, beetles are found on the sunny sides of trunks and larger branches. Females spend much of the time running over the surface, probing the bark with their ovipositors for oviposition sites. Females mate and begin ovipositing in 4 to 8 days and live about a month. Females lay about 100 eggs each, depositing them singly in cracks or crevices of the bark, under bark scales, and at bark injuries. Eggs hatch in 8 to 16 days. Newly hatched larvae chew through the bark and feed in the phloem and surface of the sapwood. Here, they prepare pupal chambers by plugging the burrows tightly with frass and pass the winter still as larvae within the pupal chambers. Larvae pupate for 8 to 14 days in spring or early summer. Adults emerge by cutting oval emergence holes through the bark. In most areas, one generation is produced per year, but in some areas, the requires 2 to 3 years.

Injury and Damage
Points of infestation can usually be detected by white, frothy sap oozing from cracks in the bark(brooks 1919a, Fenton 1942, Moznette and others 1931). Bark gradually becomes darkened, wet, and greasy in appearance. Little or no frass is ejected except at cracks in the bark. Attacks occur on both trunks and branches and are most common on the sunny aspect trees. Burrows under the bark are broad and irregular and packed tightly with fine, sawdust like frass. In young trees with thin bark, tunnels are usually long and winding, sometime encircling the tree. Injured areas usaully become depressed, and later the bark may split at injured sites. In older trees with thick bark, burrows are confined to a circular area within the bark. Wounds may be enlarged by succeeding generations. This borer generally attacks trees that have recently been transplanted, stressed, or whose bark has been damaged by tools, disease, rodents, sunscald, or other insects. Leaning and drought stressed trees are especially attractive to beetles. Injury results from larvae tunneling in the bark and cambium. Trees 5cm or less in diameter may be girdled and killed, and larger trees may be severely weakened and scarred. Because wooded tracts often harbor large populations, damage is usally most prevalent when plantings are close to woodlands or old declining orchards.

From: Solomon, J.D. 1995. Guide to insect bores of North American broadleaf trees and shrubs. Argic. Handbk. 706. Washington, DC: U.S. Department of Agriculture, Forest Service. 735p.

The Threat
The emerald ash borer (EAB) is a very small but very destructive beetle. Metallic green in color, its slender body measures 1/2 inch in length and 1/8 inch wide. The average adult beetle can easily fit on a penny.

Native to China and Eastern Asia, the EAB probably landed in North America hidden in wood packing materials commonly used to ship consumer goods, auto parts, and the like. Although no one can say for sure when EAB arrived in southeastern Michigan, the scientific community believes the beetle went undetcted for 5 o 7 years, based on its widespread distribution and destrction. EAB was officially identified in the summer of 2002.
This beetle is currently known to be responsible for the death or decline of more than 6 million ash trees in a 13-county area around detroit. EAB has also impacted various communities in Essex County, Ontario, and the Canadian city of Windsor, across the Detroit River. Canadian officials estimate that between 100,000 and 200,000 ash trees are infested.

Although large EAB infestations are concentrated in Michigan and parts of Canada, the States of Ohio, Maryland, Indiana, and Virginia have also found EAB in smaller, somewhat contained areas.

In terms of the range and extent of the EAB infestation in North America, the human element is of particular significance. Unknowingly, people's behaviors associated with everyday living and commerce have greatly contributed to the spread of the EAB. The movement of any ash tree products (e.g. branches, logs, wood chips larger than 1 inch, nursery stock, and firewood) advances the spread of EAB. Thus, human behavior is a defining factor in the spread of EAB.

Signs and Symptoms
It is extremely difficult to determine whether an ash tree is infested or not infested with EAB because tree decline is usually gradual. Early symptoms of an infestation might include dead branches near the top of a tree or perhaps wild, leafy shoots growing out from its lower trunk. D-shaped tunnels are significant signs of EAB.

If a tree is infested with the EAB, tree removal is recommended as the most effective way to eliminate these exotic pests and prevent the species' further spread. By felling a tree and chipping it into pieces 1 inch across or smaller, no viable larvae will remain.

Treatment options may eventually be approved for some homeowners living in a generally infested area where suppression efforts are being used, with the understanding that treatments are not a cure. At best, a homeowner might only prolong a tree's decline. Every EAB-infested tree will die.

Cooperation is Key
The public at large is esential to eliminate this pest. Below are some things you can do now to lessen the likelihood of EAB's becoming established in the United States.

Don't move firewood. Humans unknowingly contribute to the spread of EAB when they move firewood. Eab larvae can survive hidden under the bark of firewood. Play it safe: don't move any firewood and you won't move any beetles.

Visually inspect your trees. Early detection is a key factor. If trees display any sign or symptom of EAB infestation, contat your State agriculture agency.

Spread the word. Talk to your neighbors, friends, and coworkers and get them onboard. Public awareness and education is an ongoing process; support the effort.

Know State and Federal regulations. Make sure you understand the regulations that govern your own State and those States and Provinces you may visit.

Ask questions. If you receive ash nursery stock, know it's origin and your supplier. EAB larvae may be hiding under the tree bark.

For More Info

www.aphis.usda.gov

www.na.fs.fed.us/spfo/eab

www.emeraldashborer.info

*All information and images courtesy of the USDA (Program Aid No. 1769)

First discovered in the United States in 1930, Dutch Elm Disease is a devastating killer of elm trees. Few varieties of elm are not susceptible to the disease, which rapidly spreads once the tree has become infected. Currently, DED has destroyed more than fifty percent of all elm trees within the Northern half of North America. Minot is no exception when it comes to the number of trees lost to the disease. Several hundred elm trees have been lost in Minot alone, since the disease was first found in Mandan, North Dakota in 1969. Only the extreme northwestern section of the state has not felt the effects of DED. Luckily, the numbers of diseased trees have declined since it first emerged 50 years ago, from over 100 cases to only 20 in 2005. Unfortunately, there is no know cure for the disease. Although preventative measures exist, most are extremely expensive and not economically possible. Therefore, the best treatment for an infected tree is to simply remove it.

Dutch Elm Disease is the result of bark beetles or root grafts that bring a fungus, known as Ceratocystis ulmi, into the tree's xylem. From the xylem (the main water and mineral conducting tissue), the fungus spreads rapidly, triggering the tree's self-survival mode. The disease will generally begin in the crown of the tree, followed by a downward progression through the larger branches of the tree. Over time, the tree will form "gums" within its tissue, ultimately causing the tree to wilt and die.

However, it is important to note that the beetle itself is not the threat to the tree. It is the fungus that is responsible for the death of the elm tree, not the otherwise harmless, native borers. Unfortunately, the beetle is a perfect host for the spores associated with the DED fungus. These spores then attach themselves to the beetle's body to gain entry into the tree. The elm bark beetle then bores into the bark of a given tree, and tunnels along the bark-wood interface. As the beetle feeds, it scores (tears) the wood. This feeding is most typical in the bark of small to medium-sized branches (those 2-4 inches in diameter). If the beetle is carrying the spores of the DED fungus, a DED infection will most likely follow. This process is responsible for many of the elm trees within North Dakota becoming infected with DED. Adjacent trees are then vulnerable to infection via root grafts.

(Click diagram for closer view)

Some of the most telling signs that a tree has DED is wilting, curling, and/or yellowing of leaves on the upper portion of one or more branches. A progressive dying of leaves and branches then follows, ultimately, killing the entire tree. A brown discoloration of the wood may also be noticed, along with streaking visible in the wood of small branches, twigs, or even the trunk. These symptoms can occur rapidly, and trees will often die within only a few months of initial infection. However, it is important to be aware that both the symptoms and progression of DED can differ greatly depending on the tree or method by which it becomes infected. For example, a tree that has been infected with DED by means of root grafting may be slower to show symptoms, accompanied by leaf flagging on suckers and lower branches. However, some trees thought to have contracted DED (by evidence of wilting and yellowing leaves) have in fact only been harmed by squirrel injuries, elm scale, or storm damage. Therefore, it is important that proper testing be done to identify DED before making a final determination concerning your tree's health.

While DED is not curable, it can be prevented and controlled to a certain degree. One way to help prevent DED from spreading is to maintain your elm and keep it healthy. This includes removing dead, weak or dying elm wood. Also, remove any woodpiles from your property containing elm logs. This eliminates potential breeding sites for the elm bark beetles, who like to colonize in such wood. Another method to prevent the spread of DED to elm in your area is by means of chemical sprays or injections. However, these treatments may produce a considerable amount of wounding, loss of leaves, and can be very costly (since the treatment will need to be repeated). Unfortunately, removing the tree completely is the only sure way to stop the spread of DED.

 

North Dakota’s harsh climate is often responsible for severe damage to landscape plants. Winter sun, wind, and cold temperatures can bleach and desiccate evergreen foliage, damage bark, and injure or kill branches, flowerbuds, and roots. Snow and ice can break branches and topple entire trees. Salt used for deicing streets, sidewalks, and parking lots is harmful to landscape plantings. Winter food shortages force rodents and deer to feed on bark, twigs, flowerbuds, and foliage, injuring and sometimes killing trees and shrubs. All is not bleak, however, as landscape plants can be protected to minimize some of this injury.

Cold Damage
Cold temperatures can damage plants in several ways. Plants that are not hardy in North Dakota will be killed or injured during the winter unless protected in a microclimate. Plants that normally grow in hardiness zone 3 (Bottineau and Turtle Mts. area) and hardiness zone 4 (most of the state including Minot) may also be injured if winter conditions are abnormally severe or plants have been stressed by the environment. Injury is more prevalent and more severe when low temperatures occur in early fall or late spring, when there is little or no snow cover during the winter or when low temperatures are of prolonged duration. Pronounced fluctuations in temperature can be extremely detrimental to plants throughout the fall, winter, or spring.

Sunscald
Sunscald is characterized by elongated, sunken, dried, or cracked areas of dead bark, usually on the south or southwest side of a tree. On cold winter days, the sun can heat up bark to the point where cambial activity is stimulated. When the sun is blocked, by a cloud, hill, or building, bark temperature drops rapidly, killing the active tissue.

Young trees, newly planted trees, and thin-barked trees (cherry, crabapple, honey locust, linden, maple, mountain ash, plum) are most susceptible to sun scald. Trees that have been pruned to raise the lower branches, or transplanted from a shady to a sunny location are also sensitive because the lower trunk is no longer shaded. Older trees are less subject to sunscald because the thicker bark can insulate dormant tissue from the sun's heat ensuring the tissue will remain dormant and cold hardy.

Sunscald can be prevented, by wrapping the trunk with a commercial tree wrap, plastic tree guards, or any other light-colored material. The wrap will reflect the sun and keep the bark at a more constant temperature. Put the wrap on in the fall and remove it in the spring after the last frost. Newly planted trees should be wrapped for at least two winters and thin-barked species up to five winters or more.

Winter Discoloration of Evergreens
Browning or bleaching of evergreen foliage during winter occurs for four reasons:

1. Winter sun and wind cause excessive transpiration (foliage water loss) while the roots are in ....frozen soil and unable to replace lost water. This results in desiccation and browning of the
....plant tissue.
2. Bright sunny days during the winter also cause warming of the tissue above ambient
....temperature, which in turn initiates cellular activity. Then, when the sun is quickly shaded, ....foliage temperature drops to injurious levels and the foliage is injured or killed.
3. During bright, cold winter days, chlorophyll in the foliage is destroyed (photo-oxidized) and is ....not resynthesized when temperatures are below 28° F. This results in a bleaching of the
....foliage.
4. Cold temperatures early in the fall before plants have hardened off completely or late spring ....after new growth has occurred can result in injury or death of this non-acclimated tissue.

Foliar damage normally occurs on the south, southwest, and windward sides of the plant, but in severe cases the whole plant may be affected. Yew, arborvitae, and hemlock are most susceptible, but winter browning can affect all evergreens. New transplants or plants with succulent, late season growth are particularly sensitive.

There are several ways to minimize winter injury to evergreens. The first is proper placement of evergreens in the landscape. Yew, hemlock, and arborvitae should not be planted on south or southwest sides of buildings or in highly exposed (windy, sunny) places. A second way to reduce damage is to prop pine boughs or Christmas tree greens against or over evergreens to protect them from wind and sun and to catch more snow for natural protection.

Winter injury can often be prevented by constructing a barrier of burlap or similar material on the south, southwest, and windward sides of evergreens. If a plant has exhibited injury on all sides, surround it with a barrier, but leave the top open to allow for some air and light penetration.

Keeping evergreens properly watered throughout the growing season and into the fall is another way to reduce winter injury. Never stress plants by under- or over-watering. Decrease watering slightly in September to encourage hardening off then water thoroughly in October until freeze-up. Watering only in late fall does not help reduce injury.

Anti-desiccant and anti-transpirant sprays are often recommended to prevent winter burn. Most studies, however, have shown them to be ineffective.

If an evergreen has suffered winter injury, wait until mid-spring before pruning out injured foliage. Brown foliage is most likely dead and will not green up, but the buds, which are more cold hardy than foliage, will often grow and fill in areas where brown foliage was removed. If the buds have not survived, prune dead branches back to living tissue. Fertilize injured plants in early spring and water them well throughout the season. Provide appropriate protection the following winter.

Dieback
Deciduous trees and shrubs can incur shoot dieback and bud death during the winter. Flower buds are more susceptible to injury than vegetative buds. A good example of this is forsythia, where plant stems and leaf buds are hardy, but flower buds are very susceptible to cold-temperature injury.

Little can be done to protect trees and shrubs from winter dieback. Plants that are marginally hardy should be planted in sheltered locations (microclimates). Plants in a vigorous growing condition late in the fall are most likely to suffer winter dieback, so avoid late summer pruning, fertilizing, and over-watering.
Root Injury

Roots do not become dormant in the winter as quickly as stems, branches and buds, and roots are less hardy than stems. Roots of most trees and shrubs that grow in North Dakota are killed at temperatures at or below 0 to +10°F. These plants survive in North Dakota because soil temperatures normally are much higher than air temperatures and because soil cools down much more slowly than air temperature.

Many factors influence soil temperature. Moist soil holds more heat than dry soil, so frost penetration will be deeper and soil temperatures colder for sandy or dry (drought) soils. Snow cover and mulch act as insulators and keep soil temperatures higher. With newly planted trees, cracks in the planting hole backfill will allow cold air to penetrate into the root zone, reducing fall root growth or killing newly formed roots.

To encourage fall root growth and to reduce root injury, mulch new trees and shrubs with 6 to 8 inches of wood chips or straw. If the fall has been dry, water heavily before the ground freezes to reduce frost penetration. Check new plantings for cracks in the soil and fill them with soil.

Snow and Ice Damage
Heavy snow and ice storms cause damage by bending and breaking branches. Multiple leader, upright evergreens, such as arborvitae and juniper, and multiple leader or clump trees, such as birch, are most subject to snow and ice damage. Relatively small trees can be wrapped together or the leaders tied with strips of carpet, strong cloth or nylon stockings two-thirds of the way above the weak crotches. These wrappings must be removed in spring to prevent girdling, and to allow free movement of the stem. Proper pruning, to eliminate multiple leaders and weak branch attachments, will reduce snow and ice damage. For trees with large wide-spreading leaders or large multi-stemmed trees, the main branches should be cabled together by a professional arborist.

Salt Damage
Salt used for deicing walks and roads in winter can cause or aggravate winter injury and dieback. Salt runoff can injure roots and be absorbed by the plant, ultimately damaging the foliage. Salt spray from passing autos can also cause severe foliar or stem injury.

To prevent salt damage, do not plant trees and shrubs in highly salted areas. Avoid areas where salty runoff collects or where salt spray is prevalent, or use salt-tolerant species in these areas. Burlap barriers may provide protection to some plants from salt spray. A thorough spring-cleaning of a Blvd will also help prevent salt damage, this can be done by raking the entire Blvd followed by using a power-washer to flush the sand and salt back into the street.
Animal Damage

Mice, rabbits (rodents), and deer can all cause severe damage to plants in the winter. These animals feed on the tender twigs, bark, and foliage of landscape plants during the winter. They can girdle trees and shrubs and eat shrubs to the ground line. Deer can cause significant injury and breakage by rubbing their antlers on trees during the fall.

Rodents
Trees can be protected from rodent damage by placing a cylinder of ¼-inch mesh hardware cloth (chicken wire) around the trunk. The cylinder should extend 2 to 3 inches below the ground line for mice and 18 to 24 inches above the anticipated snow line for rabbit protection. Hardware cloth can be left on year-round, but it must be larger than the trunk to allow for growth. For small trees, plastic tree guards are also effective. You can protect shrub beds from rabbits by fencing the beds with chicken wire; however, check such fenced areas frequently to ensure a rabbit has not gained entrance and is trapped inside.

If you have many trees or shrubs to protect, using screens and wraps may be too expensive and time consuming. In such situations, repellents may be the best solution. Remember that a repellent is not a poison; it simply renders plants undesirable through taste or smell.

The most effective repellents for rodents are those containing thiram, a common fungicide. You can either spray or paint repellents on trees and shrubs. Repeat applications are necessary particularly after heavy precipitation.

If these methods are ineffective, commercial baits containing poisoned grains are available. However, baits may be hazardous to humans, pets, and beneficial wildlife. Injury or death can result for animals that eat the bait directly and for animals that consume bait-killed rodents. Shelter or containerize baits so they stay dry and are accessible only to targeted rodents. Beverage or coffee cans laid on their sides work well for this purpose. Trapping and shooting, where legal, will also control rodents.

Deer
Deer feed on and damage terminal and side branches of small trees and shrubs. Repellents containing thiram provide some control if feeding pressure is not extremely heavy. Plants can be sprayed or painted with the repellent; however, the most effective procedure is to hang heavy rags near the plants to be protected that have been dipped in concentrated repellant. Repeated plant applications or dipping of rags is necessary. Deer can also be successfully excluded with fencing. To be effective, fences must be high and constructed properly. If deer are starving, there is little that will prevent feeding. Providing more palatable forage may help, but it may also attract more deer.

Conclusion
Although plant cold hardiness and winter injury are common concerns associated with North Dakota winters, appropriate plant selection, selecting the proper site, proper cultural practices, and preventive maintenance will significantly reduce or prevent severe injury or loss of landscape plants.

Even though plants respond differently to winter stress and each winter provides a different set of stressful conditions, plants possess a remarkable ability to withstand extremely severe winter conditions. North Dakota winters should not discourage planting of traditional or new plant species.