Inspector Findings in Kentucky

You should have received your nursery license application in the mail last month. Many of you have already returned it and we thank you for your quick reply. For those of you who have not yet paid, please do so as soon as possible.

The adult male gypsy moth began to fly around the 4th of July this year and some of the traps placed in the state are showing positive catches. So far, moths have been captured in Boone, Bracken, Carroll, Fayette, Fleming, Jessamine, Madison, Mason, and Trimble counties.

By Ric Bessin, Extension Entomologist

We have received several reports of dogwood sawfly during the past week. The dogwood sawfly will take on several forms while in the larval form. As young larvae (late June-early July) they feed in groups and skeletonize leaves. As they grow, the larvae become covered with a white waxy coat and they disperse over the tree feeding on leaf margins. They eat the entire leaf, leaving only the midrib. The last instar is straw colored with numerous black spots along its body and can also cause some damage as it searches for an overwintering site. While they prefer to overwinter in rotting wood, they can also burrow into some types of composition siding.

Because sawfly larvae are not caterpillars, sprays containing Bacillus thuringiensis are not effective. Dogwood sawfly larvae can be controlled on dogwoods with sprays containing acephate (Orthene T&O), carbaryl, or cyfluthrin. There is one generation per year.

By John Hartman, Extension Plant Pathologist

We are receiving laboratory specimens and getting numerous reports of maple trees or parts of trees dying in landscapes throughout Kentucky. The problem most often involves well-established sugar maples. Homeowners usually report a sudden wilting and death of their trees; in some cases this is true, but in others, twig growth and tree ring analysis suggest that some of the dying maple trees have not been growing well for some years.

There does not seem to be a single cause for the decline and death of landscape maples this year. We have observed a number of factors that have caused death or triggered decline and death of maples, including:

* Verticillium wilt. Often developing on one side of the tree first, branches progressively wilt and die throughout the tree during the growing season. Where infections occurred late in the previous season, trees may not have even leafed-out this year, or if they did, they immediately died. Mild winter temperatures may have allowed this soil-borne fungus to be more active than usual, but we also saw considerable activity from this disease last summer.

* Girdling roots. Offending roots may not be visible above ground, but if the tree trunk does not have the normal buttress root flare at the base, and instead, goes straight into the ground like a telephone pole, self-girdling roots should be suspected. Trees with girdling roots may decline over a period of years, but then may collapse suddenly.

* Canker and collar rot. We have diagnosed some cases of Phytophthora bleeding canker and collar rot on maples this year. Water-soaked bark spots have been observed on trunks of affected trees. Collar rot, causing bark decay and wood staining, if well developed, can cause death of the top of the tree. Usually, collar rots and bleeding cankers lead to gradual decline of infected trees. The fungus Phytophthora is favored by high soil moisture levels, especially temporary flooding.

* Restricted rooting space. Sugar maples planted as street trees sometimes lack space for their roots to exploit. Such trees with inadequate root systems would be especially vulnerable to drought and temporary flooding stresses.

* Soil compaction from foot traffic, construction, or other activities crushes small roots and makes soils impervious to invasion by new roots. Affected maples may decline.

* De-icing salts. Sidewalk and road salt were not used much this past winter, but where they were used and where treated snow is piled over the root system, accumulations could reach levels injurious to maples which are fairly sensitive to excess soil salts.

* Mechanical injuries. Construction, such as laying utilities, severs roots and triggers decline. Wounds to the trunk or large branches can also have negative effects on maple tree health.

* Opportunistic fungi. Root, butt, and trunk rotters such as Ganoderma lucidum are found on some declining trees. In addition, canker and canker-rot fungi such as Botryosphaeria obtusa, Nectria cinnabarina, Cerrena unicolor, and Stegonosporium pyriforme are capable of invading weakened plants and causing branch dieback.

Although some infectious diseases are involved in the current wave of maple declines and death, much of the problem lies with urban stresses. In addition, recent hot weather, wet spring conditions, mild winter temperatures, drought last summer, and any number of weather extremes from several years ago could be involved. In almost all cases, there is no reversing the decline. For those with still-healthy maples, continue to provide good growing conditions and be observant for the first indications of maple distress such as premature fall color, branch tip dieback, and girdling roots.

By Mike Potter, Extension Entomologist

Cicada killers are now flying, prompting frantic calls from some homeowners. Despite their menacing appearance (up to 2 inches long with rusty red head/thorax, amber-yellow wings, and black and yellow striped abdomen), the wasps seldom sting unless handled or otherwise molested.

Cicada killers do not live in communal nests like hornets or yellowjackets. They overwinter as larvae within cocoons, deep in the soil, emerging as adults from late-June through July. The females feed, mate, and excavate burrows in the ground about ½ inch in diameter, ending in a series of brood chambers. Excess soil is pushed out of the burrow, leaving a small, U-shaped mound of dirt at the entrance. Each female excavates numerous burrows and provisions them with adult cicadas which she ambushes, paralyzes with her venom, and stuffs into individual brood chambers. She then lays an egg on top, backs out, and seals the cell behind her. The egg hatches within a few days and the hungry larva devours the offering, eventually transforming into a pupa the following spring.

Management - Cicada killers seldom sting and the females normally do not defend their burrows. The males, while incapable of stinging, sometimes dive-bomb passers-by, or hover about one's head or body. Insecticide treatment may be warranted where the soil burrows become unsightly.

from Iowa State University Dept. of Entomology website: (http://www.ipm.iastate.edu/ipm/hortnews/1994/7-29-1994/yelcat.html)

The yellownecked caterpillar is a common site on crabapple, pin oak and birch trees. Other fruit and shade trees may be infested also. This insect is named for the large yellow dot that appears behind the head (where the neck would be, if caterpillars had necks) of mature larvae. Small caterpillars do not have the characteristic yellow spot though a light colored area may be visible. Small larvae are purplish, with slender white lengthwise stripes. Very small larvae feed in a cluster but as they grow they disperse throughout the entire tree. Large larvae change to a black-and-white striped pattern and sparse, fine hair on the body becomes apparent. Full grown length is approximately 2 inches.

by Lee Townsend, Extension Entomologist

Tuliptree scale is a large scale measuring about 1/3". The hemispherical shape may be distorted due to crowding together on twigs. Honeydew and sooty mold accompany infestations. This species is common on tuliptree, but has also been reported on walnut and a few other plants. There is one generation per year with crawlers active in late August.

In general, controls will be more effective if the scale population on a plant is first physically reduced by pruning out heavily infested and sickly branches. Horticultural oil sprays kill primarily by smothering, so they will be less effective against scales crowded together or occurring in layers the plant. Insecticidal soaps provide a new alternative. They are very effective against both active and settled crawlers. Oils and soaps are safe to use and are especially good choices for sensitive areas, such as where people are present soon after treatment. Because of their short residual, they help to conserve beneficial species.

Horticultural spray oils kill all stages of scales that are present at the time of application, and often give good control. Most trees and shrubs can tolerate application of light (summer oil) even during the summer months. Refer to the product label for guidelines on plant sensitivity and any temperature restrictions. Oil products labeled as summer, superior or Volck oil are of the highest grade and may be used on tolerant plants during either the growing season or the dormant season, but at different spray concentrations.

An alternative to oil sprays are contact insecticides applied during the growing season when the crawler stages of the scales are present. The presence of crawlers can sometimes be determined by sharply tapping an infested twig or branch over a white paper. Crawlers are often orange, brown or purple and appear as moving specks of dust. Because of their waxy protective covering, other stages of scales are not readily controlled by contact insecticides. Contact insecticide sprays will not reach crawlers that have settled under old scales.

Insecticides registered for scale crawler control on outdoor plants include: Cygon (dimethoate), Dursban (chlorpyrifos), Diazinon, Malathion, Orthene (acephate) and Sevin (carbaryl). Although resistance to insecticides may occur in some cases, failure of contact sprays is more often the result of not timing the applications to coincide with crawler activity. Even when sprays are timed for optimum effect, complete control may not be achieved by single applications if crawler activity is spread over an extended period of time, or if populations are heavy and crawlers are under old scale shells. Thorough spray coverage is essential for good control.

The Asian longhorned beetle (Anoplophora glabripennis) is an extremely destructive insect that has been found in Brooklyn and Amityville NY (first found in August 1996) and in Chicago, IL (July 1998). This is the first time that these beetles have been seen outside of their native home of Japan, Korea, and southern sections of China and experts are unsure exactly how the beetles got here. The beetles are known to attack healthy maple trees (including Norway, sugar, silver, red and others), horsechestnut, poplar, willow, elm, mulberry, and black locust. It also may attack other hardwoods. In New York, the beetle appears to prefer maples and horsechestnuts.

The large, bullet-shaped beetle is shining coal black with white spots and is about an inch long. On its head are very long, horn-shaped antennae that are black with white rings and are longer than the insect itself. The plate-shaped feet are black with a whitish-blue upper surface. The beetle bores into the tree, making a large (1/4-3/8 inch diameter) round hole anywhere on the tree so that it can lay its eggs. These eggs hatch into white, worm-like larvae that bore into tree trunks and branches, causing heavy sap flow from wounds and large sawdust accumulation at tree bases. The adult beetle is a poor flier and will travel no more than 1000 yards to search for other food sources (trees and leaves) and mates. In most cases, the beetle will exit the tree after emerging from pupae stage, only to reattack the same tree in another location.

In an effort to eradicate the Asian Longhorned Beetle, New York implemeted a 4 step plan in the fall of 1996. The first step was to survey trees within the affected areas and determine the number damaged. Because of the weak migration movement and size of holes, surveys quickly revealed to what extent the beetle had moved through a community of trees. The survey showed that approximately 900 trees were infested with this beetle.

The second step was to implement an emergency quarantine that prohibited the movement of any suspected tree or wood products into or out of the affected areas.

The third step is the systematic removal of infested trees from the affected areas. These infested trees will be cut, chipped and incinerated. Chipping and burning of infested trees has proven effective in eliminating the beetle, as it lies dormant in the tree during this time of the year.

The last step will be a replanting effort aimed at the replacement of trees to fill the gap that will be left by the initial stages of this program. Both the Empire State Forest Products Association and the New York State Nursery and Landscape Association will play major roles in this replanting effort.

The estimated costs for this project run in excess of $500,000. These costs will be shared by a consortium of federal, state and municipal agencies as well as private organizations dedicated to the preservation of trees in urban areas.

Taxus mealybug is easily seen when looked for, the symptom more readily noticed from several feet away is sparse yellow foliage covered with sooty mold. These mealybugs occur on stems and branches, and tend to cluster in forks of branches. They overwinter as nymphs that become active in the latter half of May, and by early summer adult females begin giving birth to live young. There are two or three generations per year. This insect has been reported from other plants such as apple, cedar, linden and maple, but is not known to reproduce on these plants

In general, controls will be more effective if the scale population on a plant is first physically reduced by pruning out heavily infested and sickly branches. Horticultural oil sprays kill primarily by smothering, so they will be less effective against scales crowded together or occurring in layers the plant. Insecticidal soaps provide a new alternative. They are very effective against both active and settled crawlers. Oils and soaps are safe to use and are especially good choices for sensitive areas, such as where people are present soon after treatment. Because of their short residual, they help to conserve beneficial species.

Horticultural spray oils kill all stages of scales that are present at the time of application, and often give good control. Most trees and shrubs can tolerate application of light (summer oil) even during the summer months. Refer to the product label for guidelines on plant sensitivity and any temperature restrictions. Oil products labeled as summer, superior or Volck oil are of the highest grade and may be used on tolerant plants during either the growing season or the dormant season, but at different spray concentrations.

An alternative to oil sprays are contact insecticides applied during the growing season when the crawler stages of the scales are present. The presence of crawlers can sometimes be determined by sharply tapping an infested twig or branch over a white paper. Crawlers are often orange, brown or purple and appear as moving specks of dust. Because of their waxy protective covering, other stages of scales are not readily controlled by contact insecticides. Contact insecticide sprays will not reach crawlers that have settled under old scales.

Insecticides registered for scale crawler control on outdoor plants include: Cygon (dimethoate), Dursban (chlorpyrifos), Diazinon, Malathion, Orthene (acephate) and Sevin (carbaryl). Although resistance to insecticides may occur in some cases, failure of contact sprays is more often the result of not timing the applications to coincide with crawler activity. Even when sprays are timed for optimum effect, complete control may not be achieved by single applications if crawler activity is spread over an extended period of time, or if populations are heavy and crawlers are under old scale shells. Thorough spray coverage is essential for good control.

from Ohio Christmas Tree Producers Manual Bulletin 670 website: (http://www.ag.ohio-state.edu/~ohioline/b670/index.html)

Although fertilization at planting time is not generally recommended, fertilization later in the Christmas tree rotation can often be beneficial. Christmas trees are essentially a foliage crop, and luxuriant foliage with good color is a definite asset when trees are sold.

Good moisture and nutrient relations are of prime importance in producing trees having desirable foliage characteristics. Earlier discussions have emphasized the importance of site evaluation, species selection and control of competing vegetation on nutrient and/or moisture relationships. In this section, the potential of using fertilization for improving foliage characteristics in established plantings is discussed.

As with any crop it would be very desirable to be able to prescribe fertilization needs of Christmas trees on the basis of soil and/or foliar analyses. However, adequate standards for making such diagnoses are not yet available. As a consequence, fertilization needs must be judged largely on the basis of indirect indicators.

Species and site characteristics often serve as a general guide to fertilization in established Christmas tree plantations. On sites with adequate water, species having relatively high site requirements such as some of the spruces, true firs, Douglas-fir and white pine may respond favorably to fertilization on coarse to moderately coarse textured soils (sands to sandy loams) and possibly even on medium to moderately fine textured soils (loams to silty clay loams). Scotch pine does not need fertilization on most sites, but it may benefit from fertilization on relatively dry, infertile areas and may show considerable foliar response to fertilization on a wide variety of sites. It is generally more difficult to obtain favorable response to fertilization with most species on either very dry or wet soils.

Thin, open growth of herbaceous vegetation on sites can also be used as an indicator of fertility needs, especially on areas where there is adequate soil moisture.

A number of materials can be used for fertilizing established Christmas tree plantings. In the absence of more adequate standards for diagnosing needs, applications of balanced fertilizers having 1-1-1 ratios such as 10-10-10 or 15-15-15 are probably as good as any other material. Where nitrogen may be deficient, fertilizers with 2-1-1 ratios (such as 12-6-6 etc.) are appropriate. Applications of high-analysis nitrogen compounds such as urea (45-0-0) or ammonium nitrate (33.5-0-0) can improve foliage characteristics when applied one or two years prior to harvesting. Research in Ohio indicates that foliage density of Norway and white spruces, Douglas-fir, Fraser fir and Scotch and white pine growing on a variety of sites improved significantly when fertilized with 150 to 225 pounds of actual nitrogen per acre treated. If individual trees are fertilized, from three ounces to one pound of the above formulations will be needed, depending on size. Care should be taken when using high-analysis nitrogen compounds to avoid excess stimulation of succulent growth that may be subject to winter injury. Excess applications of soluble nitrogen compounds can also severely injure or kill small trees, particularly on sandy soils.

Applications of fertilizers to established Christmas tree plantations should be carried out in conjunction with good weed control practices, including judicious use of herbicides in bands or spots around trees. Band applications of fertilizers are generally more desirable than broadcast applications because less material is used and it is placed only in areas where it is needed. Banding also avoids excessive stimulation of herbaceous growth between rows. Methods of banding vary. Hand applications can be used by applying a circular band of fertilizer 8 to 12 inches from stems, or mechanical equipment can be used. Early spring is probably the best time to apply fertilizers in established Christmas tree plantings.