Ash Trees are suffering this year in record numbers.

Ash Trees are suffering this year in record numbers  Common symptoms associated with attack by boring insects are, branch dieback are thinning canopies and epitomic branching.

The canopy of the tree may have only the lower branches still full of foliage and the top with only a scattering of leaves. In addition, the lower branches and trunk may have single or clusters of upright shoots these are called epicormic shoots and occur along the branches or trunks of stressed trees.

A symptom common with ash trees infested by carpenter worms and other ash borers is bark shredded off by woodpeckers searching for the larvae. Fresh missing bark, particularly over an extensive area of the trunk, is one of the best indicators that the tree may be infested by the borer.

If these indicators are present, look for signs of activity of a boring insect in the trunk or dying branches. Sometimes only the upper branches will show insect activity, and if possible these should be the first examined. Signs to look for are the size and shape of exit holes on the bark and the pattern of any insect tunnels beneath the bark.

Emerald Ash Borer

A destructive metallic green beetle, emerald ash borers (EAB) invade and kill all types of ash trees, Fraxinus species. Green, white, Autumn Purple, and all others are susceptible.

EAB kills trees in 2 to 4 years after initial infection. It has killed millions of trees in the Midwest and is slowly spreading across the country.

Damage

An EAB infected tree has a thin or dying crown and erratic growth along the trunk of the tree. It is often a popular site for woodpecker feeding as the bird is harvesting the beetles in the bark. Finally upon close inspection of the trunk you might see unique "D" shaped holes. This is where the beetle exited the tree.

Control

There are a host of preventive treatments available for trees within 15 to 20 miles of other infected trees. Treatment outside this risk zone is not prudent. Keep in mind that treatments must be done each year for the life of the tree and will not be effective against other injuries that may compromise the tree's health.

Leopard Moth

Leopard Moth - Zeuzera pyrina Phylum: Arthropoda - Class: Insecta - Order: Lepidoptera - Family: Cossidae Goat Moth

The Leopard Moth is one of only three of the approximately 700 species of Cossidae moths (Leopard and Goat moths) to occur in Great Britain.

The large furry white thorax of the Leopard Moth displays 6 dark spots arranged in two lines, and its white, almost transparent wings, are also covered in dark spots. The Male has comb-like antennae which are one of the significant features in accurate identification.

The Leopard Moth lives in gardens, open woodland, parks and orchards. The forewing of the Leopard Moth ranges between 22 and 35mm Distribution In Britain the Leopard Moth is most common in southern England and has only once been recorded from Ireland. Lifecycle The Leopard Moth is shortlived because it is unable to feed. It over-winters two or three times in its larval form and feeds on the stems and leaves of various trees and shrubs.

The larval foodplants of the Leopard Moth include many trees and shrubs both in parkland and gardens. They include various fruit trees such as Cherry, Apple, Pear and Black Currant and the larvae have been known to inflict considerable damage to fruit crops. The larvae also live and feed on Hawthorne, Honeysuckle, Beech and Ash trees.

Ash Fly

The gnat-sized ash whitefly infests and seriously damages a variety of landscape trees and ornamentals.

In California it has attacked apples, pears, pomegranates, apricots, peaches, citrus, olive, ash, and other, shade trees. The whitefly has apparently not affected any native desert plants, but infestations appear to be spreading to more host plants than are normally attacked in its native European range from Ireland to Egypt. The Ash whiteflies can kill full grown trees by repeatedly destroying all of the tree's leaves.I have witnessed this myself.( Warner)

In the United States, ash whitefly was first collected in Los Angeles County, California in 1988, and then spread to other counties. It was later discovered in Arizona, Nevada and New Mexico.

It appeared in Raleigh, North Carolina in 1993. It is also reported from Arizona, Georgia, Nevada, New Mexico, South Carolina and Texas. A successful biological control program using a parasitic wasp reduced infestations to undetectable levels (western states) or possibly eliminated the infestion (North Carolina). In 2010, it was discovered in central (Lake Buena Vista) and northwestern (Panama City) Florida (Stocks and Hodges 2010). 

Adult: The adult appears much like a typical whitefly with a light dusting of white wax. Depending on temperature, females live from 30 to 60 days, while males live an average of nine days. This rapid development time, without the presence of the parasitiod, initially produced numerous generations per year in California, whereas only two to three generations were reported in Egypt. Plus, the ability of all life stages to overwinter on non-deciduous hosts allows a rapid build-up in population at the start of the season (Stocks and Hodges 2010). Winged females lays eggs on the underside of the leaves. When the nymphs emerge, they rarely move far and feed on the plant sap until pupation (Gillespie 2000). 

Clearwing Ash Borer

Clearwing ash borers typically leave exit holes about the size of a pencil.

The most common ash borer in South Dakota is our native clearwing ash borer (Podosesia syringae). This insect makes an exit hole about the size of a pencil (1/4 inch) and usually the ground beneath the holes is covered with powdery sawdust. The galleries are often found deep within the wood, rather than just beneath the bark, and they are usually clean of material.

Carpenterworm

Carpenterworm (Prionoxystus robiniae) is another common boring insect of ash trees. This insect creates an exit hole about 1/3 inch in diameter, slightly larger than a pencil. There will often be sawdust around the hole and on the ground beneath the tree.

Sap may also be oozing from the holes and sometimes the empty pupal case left by the emerging adult insect can be found attached to the bark surrounding the exit holes. Above: Exit holes left by carpenterworms appear slightly larger than a pencil.

Pigeon Tremex

Pigeon tremex. The pigeon tremex (Tremex columba) is a native insect to North America. It is a type of wood boring wasp in the horntailfamily Siricidae. The pigeon tremex develops in a wide range of hardwood trees that are in advance stages of decline, including elm, maple, and ash.

Adults of this insect emerge from trees in midsummer. The females, which are large,
brown cylindrical bodied wasps, can sometime be observed as they search the bark of host plants. Periodically females will drill into trees with a long ovipositor and, when the plant is suitable, will lay eggs into the wood. Pigeon tremex also introduces white rot fungi when laying eggs, which will produce decay in the area where the young wasps develop.

Feeding occurs deeply into the wood, producing riddling that may extend into the center of the plant and these tunnels are round in cross section. Larvae of the pigeon tremex are cream colored with a cylindrical body. The head is large, compared to the other wood borers, but, except for the jaws, it is not darkened.

Pigeon tremex is restricted to ash trees that are in advanced decline and it is not a primary pest of ash. Adults produce round, smoothly cut holes when exiting through the bark

Redheaded Ash Borer

Redheaded ash borer. The redheaded ash borer (Neoclytus acuminatus) is a native insect to North America. It is a type of beetle in the “roundheaded borer” (larval name) or “longhorned beetle” (adult name) family Cerambycidae. The redheaded ash borer
develops in a wide range of hardwood and,despite its common name, is infrequently found in ash; fruit trees are more commo hosts of this insect in Colorado.

Adults of this nsect emerge from trees from June through August, cutting their way through the bark. They feed for a brief period on foliage of host plants and, after mating and maturation of the eggs, the females will lay eggs in small pits that they chew into the bark of host trees.

Upon egg hatch the newly emerged larvae tunnel into the trunks or limbs. Feeding occurs deeply into the wood, producing riddling that may extend into the center of the plant and these tunnels are semicircular in cross section. Larvae of the redheaded ash borer are cream colored with a small head marked with pronounced dark jaws. The general body for is somewhat cylindrical. They can be distinguished from larvae of the lilac/ash borer in that they lack the small prolegs on the underside of the abdomen. Larvae of the pigeon tremex, a type of horntail wasp. Perfectly round exit holes are produced when the adult of the pigeon tremex horntail emerges from the trunk.

Redheaded ash borer is almost entirely restricted to ash trees that are seriously injured or in advanced decline and it is not a primary pest of ash. Adults produce generally round, slightly semicircular, holes when exiting through the bark.i

Ash Bark Beetles

Another group of insects that can be found boring into dying ash are the ash bark beetles (Hylesinus). There are at least two species in South Dakota, the eastern ash bark beetle (H. aculeatus) and the western ash bark beetle (H. californicus). These insects create a round exit hole 1/16-inch diameter, about the size of a BB, and often these holes will encircle a shoot. The galleries beneath the bark consist of a main tunnel with numerous smaller tunnels run off from it and following the wood grain.

Llac Ash Borer

Lilac/ash borer. The lilac/ash borer (Podosesia syringae) is a native insect to North America and is the most commonly encountered wood borer in ash throughout Colorado. It is a type of moth in the “clearwing borer” family Sesiidae.
Adults of this insect emerge from trees during warm days in mid spring. In warmer areas and during warm seasons emergence may begin to occur in April, although the adults are more commonly encountered in May and early June. After mating, the females will lay eggs in cracks on the bark of ash trees. Most egg laying is concentrated in the lower trunk, sometimes extending into the lower scaffold limbs and a bit above. Lilac/ash borer adults do not possess chewing mouthparts so they do not feed on leaves.

Upon egg hatch the newly emerged larvae tunnel into the trunks or limbs producing irregular gouging wounds just under the bark. Later stage larvae may extend the tunnels deeply into the trunk and lilac/ash borer will produce more generalized riddling of the trunk and limbs than do the other borers associated with ash. Larvae of lilac/ash borer are cream colored with a dark head and can be distinguished from the other wood borers by a series of short, paired prolegs on the underside of abdomen, each tipped with a series of small hook (crochets).Larva of the lilac/ash borer showing prolegs
tipped with hooked crochets on the abdomen.

Flatheaded Appletree Borer

Flatheaded appletree borer. The flatheaded appletree borer (Chrysobothris femorata) is a native insect to North America and is associated with several hardwood trees in Colorado including oak, maple, ash, and apple. It is a type of beetle in the “flatheaded
borer” (larval name) or “metallic wood borer” (adult name) family Buprestidae – as is the emerald ash borer.

Adults of this insect emerge from trees during May and June, cutting their way through the bark. They then move to the crown of ash trees and for a period of weeks will feed on the foliage. After mating and maturation of the eggs, the females will lay eggs on the surface of the bark of host trees, with egg laying concentrated on limbs that are showing decline or injury.

Upon egg hatch the newly emerged larvae tunnel into the trunks or limbs. Feeding occurs shallowly, in the cambium. Tunnels have a meandering form, gradually increasing in diameter as the insects grow, and are packed with fine, somewhat granular, sawdust-like excrement (frass). Just prior to pupation the larvae bore a bit more deeply into the trunk and form a cell within which they will pupate. Larvae of the flatheaded appletree borer are cream colored, have a small head with pronounced dark jaws, feature a broadly flattened area in the behind the head, and have a very elongate and somewhat flattened body. The broad area behind the head, wider in the flatheaded appletree borer, can generally be used to distinguish this insect from emerald ash borer. However, when the question of proper identification of flatheaded borers in ash is necessary, larvae should be sent for expert identification. Tunneling in a dying ash limb produced by larva of the flatheaded appletree borer.

Chalara Ash Dieback

Chalara ash dieback, which is caused by a fungus called Chalara fraxinea, causes leaf loss and crown dieback in affected trees, and can cause trees to die.

The disease was first detected in Britain in March in nurseries and recently planted sites, before being discovered in woodlands and forests.

Experts believe the fungus in mature woodlands has swept in from northern France and warn that little can be done to stop the wind-borne disease from spreading.

Leaf Rust

When you see orange, gold, or reddish spots rupturing leaf surfaces, you're dealing with rust. While it rarely kills plants, rust fungus makes leaves unsightly and weakens the plant by interfering with photosynthesis, the process a plant uses to make food. Each plant species that is susceptible to rust, hosts a particular rust species that may vary from other rust species in appearance.

Damage
Leaves are discolored or mottled yellow to brown. Powdery fungal clusters appear on the leaves. The powdery material can be scraped off. Leaves may become twisted and distorted and may dry and drop off. Twigs may also be infected.

Control
Many rust fungi are usually harmless to the plant and rarely require control measures. Where practical, remove and destroy leaves in fall. Several fungicides are available that can control rust fungi. Check with your local extension service for current recommendations.

Fire Blight

Aptly named, fire blight gives trees and shrubs the appearance that portions of their branches have been scorched by fire. Blossoms and leaves of some twigs suddenly wilt and turn brown or black. Fire blight is caused by bacteria that are particularly active in warm, moist weather. Bees, rain, and infected pruning tools spread the disease.

 

Damage
Tips of infected branches may hang down. The bark at the base of the blighted twig takes on a water-soaked appearance, then looks dark, sunken, and dry. Fire blight attacks a few twigs at a time to create a flaglike effect of dead foliage on different areas of the plant.

Control
Prune out infected branches about
12 inches beyond any discoloration and destroy them. Disinfect pruning tools by dipping after each cut in a solution of 1 part chlorine bleach and 9 parts water. Avoid excess nitrogen fertilizer in spring and early summer. It forces succulent growth, which is more susceptible to fire blight infection. 

Powdery Mildew

Powdery mildew forms a white coating on leaf surfaces during dry, cloudy weather with high humidity. It is caused by any one of several fungi. Plants growing in shaded areas are often the most affected.

 

Damage
Leaves are covered with a thin layer or irregular patches of a powdery, grayish-white material. Leaves may become distorted. Infected leaves may turn yellow or red and drop. In late fall tiny black dots are scattered over the white patches like grains of pepper.

Control
When planting new trees and shrubs, choose resistant varieties. Some groups of highly susceptible plants, such as crape myrtles, crabapples, and lilacs, have cultivars selected for resistance to powdery mildew. Several fungicides are available that will control this mildew.

Gall

A destructive metallic green beetle, emerald ash borers (EAB) invade and kill all types of ash trees, Fraxinus species. Green, white, Autumn Purple, and all others are susceptible.

EAB kills trees in 2 to 4 years after initial infection. It has killed millions of trees in the Midwest and is slowly spreading across the country.

Damage

An EAB infected tree has a thin or dying crown and erratic growth along the trunk of the tree. It is often a popular site for woodpecker feeding as the bird is harvesting the beetles in the bark. Finally upon close inspection of the trunk you might see unique "D" shaped holes. This is where the beetle exited the tree.

Control

There are a host of preventive treatments available for trees within 15 to 20 miles of other infected trees. Treatment outside this risk zone is not prudent. Keep in mind that treatments must be done each year for the life of the tree and will not be effective against other injuries that may compromise the tree's health.

Witches Broom

Characterized by odd-looking clusters of intense growth, shoots infected with witches' broom grow out of lateral buds on branches in the vague pattern of a broom.

 

 

 

Damage

A prolific broom infection has the potential to pop up all over the tree, destroying it in some cases. Trees are susceptible to infection by witches' broom at vulnerable points such as where pruning or injury has taken place.

Control

Prune and destroy brooms and injured branches. Spray the affected tree with locally recommended fungicides in fall or early spring.

Canker

A localized dead area on a trunk or branch, cankers are caused by everything from mechanical damage inflected by a lawn mower to environmental stress in the form of frost cracks and sunscald to types of fungi and bacteria.

 

Damage

On young or smooth-barked trees, the surface of the canker is often discolored and tissue around the canker is enlarged. The size of a canker can range form a small lesion on a branch to a massive dead area on the plant's trunk. Cankers on young trees can kill them. Cankers rarely kill established trees but they may cause serious growth deformities.

Control
Most canker-causing fungi infect stressed or injured trees. The best defense against canker is prevention. Keep trees healthy and prevent infection. In winter, wrap young, thin-barked trees, such as maples and apples, to prevent sunscald and frost cracks. In periods of drought, water trees thoroughly.

In the case of infectious cankers, remove branches six to 12 inches below the canker. Dead or dying branches should also be removed. Prune during dry weather to minimize the spread of the disease.

Leaf Spot

Leaf spot is a fungi that causes red spots that rot holes in foliage. It spreads rapidly during cool, wet spring weather, when new foliage is developing. Ornamental cherry trees are especially vulnerable to leaf spot.

 

 

Damage

Infected leaves develop spots, then turn yellow or brown and drop off the tree.

Control

Shake infected leaves from the tree onto a disposable sheet or tarp and destroy. Prune the tree to encourage better air circulation and mulch well to prevent the fungi form splashing up from the ground.

Japanese Beetle

Adult Japanese beetles feed on flowers and leaves of various trees and shrubs, such as linden, crabapple, birch, and rose. When the beetles find a food source, they release a scent that attracts more beetles. Females lay eggs in the soil, which hatch into grubs, a major lawn pest.

 

Damage
Japanese beetles eat leaf tissue between the veins, creating a skeletonized effect. They may also eat large holes in flower petals.

Control
Treat for grubs in your lawn and you'll reduce the number of Japanese beetles (unless your neighbor doesn't control grubs, in which case beetles will invade your garden). A fungus called milky spore controls grubs but may take a few years to build up an effective concentration. Adult beetle traps may lure more beetles than you already have in your garden. Plant trees and shrubs that beetles don't like to feed on. Arborvitae, lilac, hemlock, holly, juniper, pine, red maple, red oak, rhododendron, and yew are a few plants that Japanese beetles rarely attack.

Bagworm

Bagworms eat leaves of many trees and shrubs. Larvae hatch in May or June and immediately begin feeding. Each larva constructs a bag that covers its entire body. Larvae pupate in the bags. When adult males emerge from pupal cases, they fly to find females and mate. After mating, the female lays eggs in the bag and it overwinters on a tree or shrub. Larvae emerge in spring to continue the cycle.

Damage
Leaves are chewed and branches or entire plants may be defoliated. Brown, 1- to 3-inch-long "bags" hang from the branches.

Control
Spray with Bacillus thuringiensis (Bt) between late May and mid-June to kill young worms. Handpick and destroy bags in winter to reduce the number of eggs and young the following year.

I hope you found this page about Ash Tree Diseases in Mesa AZ useful. If you have any questions about Tree Disease please contact our Tree Service to schedule an appointment. We have been treating sick trees for over 50 years. We currently serve, Mesa AZ, Gilbert AZ, Chandler AZ, Scottsdale, Phoenix AZ and all of Maricopa County AZ.

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