Inspector Findings in Kentucky

Nursery License Renewal

You should have received your nursery license renewal form in the mail in June.  Most of you have returned the application and we thank you for your quick reply.  For those of you who have not yet paid, please do so as soon as possible. 

Fire Ants Found in Kansas

Kansas nursery inspectors found imported fire ant in 5-6’ B&B junipers at a nursery in Pittsburg, Kansas.  The junipers came from Honey Creek Nursery in Grove, Oklahoma.  It is unsure if Honey Creek Nursery grew the plant material or if it came from another source.  If you received any plant material from this nursery, please let us know so that we can inspect the stock for fire ants.  We do not want to let this pest get a foothold in our state.

Since the imported fire ant has been located in several new states in the past few years, we thought it would be good to review a little bit about the history and biology of the imported fire ant. 

Fire Ant Biology

From North Carolina State University, Texas A&M and University of Arkansas websites

The red imported fire ant (Solenopsis invicta) is a native of South America that was accidentally introduced into the southern United States around 1940. Over the past 50 years, this insect has spread throughout much of the southern and southeastern United States.  In recent years, red imported fire ants have been discovered in California, and Maryland.  The ants are relatively small (3-6 mm in length) and red to reddish brown in color. They nest in sandy soils and often build large interconnecting colonies with multiple queens. Survival is best in mild temperate climates where winter temperatures rarely fall below 10°F and rainfall exceeds 25 cm (10 inches) per year.

Red imported fire ant colonies consist of the brood and several types of adults:

Winged males (distinguished from the females by their smaller heads and black bodies)

     Red-brown winged females

     Workers

Worker ants are wingless, sterile females. They protect the queen by defending the nest from intruders, by feeding the queen only food that the workers have eaten first, and by moving the queen from danger. They also forage and care for the developing brood. The brood is made up of cream-colored eggs, larvae, and pupae of all the castes.

The winged forms, or reproductives, live in the mound until their mating flight, which usually occurs in the afternoon soon after a rainy period.  Mating flights are most common in spring and fall. Males die soon after mating, while the fertilized queen alights to find a suitable nesting site, sheds her wings, and begins digging a chamber in which to start a new colony.  Sometimes, several queens can be found within a single nesting site.

A newly mated queen lays about a dozen eggs. When they hatch 7 to 10 days later, the larvae are fed by the queen. Later on, a queen fed by worker ants can lay up to 800 eggs per day. Larvae develop 6 to 10 days and then pupate. Adults emerge in 9 to 15 days. The average colony contains 100,000 to 500,000 workers and up to several hundred winged forms and queens. Queen ants can live 7 years or more, while worker ants generally live about 5 weeks, although they can survive much longer.

There are two kinds of red imported fire ants -- the single queen and multiple queen forms. Workers in single queen colonies are territorial.  Workers from multiple queen colonies move freely from one mound to another, which has resulted in a dramatic increase in the number of mounds per acre. Areas infested with single queen colonies contain 40 to 150 mounds per acre (rarely more than 7 million ants per acre). In areas with multiple queen colonies, there may be 200 or more mounds and 40 million ants per acre.

The red imported fire ant builds mounds in almost any type of soil, but prefers open, sunny areas such as pastures, parks, lawns, meadows and cultivated fields. Mounds can reach 18 inches in height, depending on the type of soil. Often mounds are located in rotting logs and around stumps and trees. Colonies also can occur in or under buildings.

Colonies frequently migrate from one site to another. The queen needs only half a dozen workers to start a new colony. They can develop a new mound several hundred feed away from their previous location almost overnight. Flooding causes colonies to leave their mounds and float until they can reach land to establish a new mound. Colonies also can migrate to indoor locations.

Fire ants can be beneficial. They feed primarily on insects and arthropod pests, which can reduce the need for insecticides in commercial agriculture.  In urban areas fire ants feed on flea larvae, chinch bugs, cockroach eggs, ticks and other pests.

Banded Ash Borer

From Guide to Insect Borers in North American Broadleaf Trees & Shrubs, USDA Forest Service

The banded ash borer and the lilac – ash borer are two closely related species.  However, adults of the banded ash borer, Podosesia aureocincta, emerge in August and September in Ohio and Virginia.  This late-season emergence distinguishes this species from that of the lilac - ash borer (Podosesia syringae) which emerges in the spring and early summer.  Banded ash borer moths emerge in late morning and mate from late morning until midday.  Eggs are deposited in bark crevices of host trees.  Young larvae bore into the bark and mine in the phloem-cambium area.  They overwinter in the mines as second-instar larvae.  In spring, they continue to enlarge the cambial mines and begin excavating galleries into the wood.  Completed galleries are 5-7 mm in diameter and 7-32 cm long.  Mature larvae enclose in a pupal chamber at the uppermost part of the gallery by plugging the tunnel tightly with frass.  They pupate from midsummer to fall (about 3 weeks).  There is one generation per year.

Injury and Damage

Injuries resemble those of the lilac-ash borer.  Crown dieback (below) and basal sprouts often indicate attack.  Oozing sap and fine frass are extruded from attack sites beginning in late summer and continue into fall.  By spring and summer, frass becomes coarse and granular and is extruded in small clumps from entrance holes, may be present in bark crevices, and often accumulates in piles around the tree’s base.  Maximum accumulation of frass occurs during May and June.  Cambial burrows can be exposed by removing the bark.  Pupal skins protrude from exit holes in bark from late summer to winter.  The seasonal evidence, irregularly shaped entrance holes, 4 to 5 mm round exit holes, together with associated overgrown bark scars indicate current and past infestation.  This borer is very destructive to ornamental and timber trees but seems less populous and more scattered than P. syringae.

Because of the life cycle differences between the two species, chemical control measures must be adapted to each.  Synthetic sex pheromones have been developed as monitors for determining the presence of adults.

Black Root Rot of Ornamentals

by John Hartman and Paul Bachi, Extension Plant Pathologists

Black root rot is most frequently observed on Japanese holly, blue holly, and inkberry in Kentucky. Susceptible blue holly cultivars include: Blue Angel, Blue Maid, Blue Prince, Blue Princess, Blue Stallion, China Boy, China Girl and Dragon Lady. While English and Chinese hollies are reportedly resistant, American and Yaupon hollies are considered to be only moderately resistant. Other ornamentals known to be susceptible include begonia, cyclamen, geranium, gioxinia, oxalis, phlox, poinsettia, sweet pea, verbena, and viola. English boxwood was also found to be susceptible in greenhouse inoculation studies. Black root rot may also affect alfalfa, cotton, cowpea, eggplant, peanut, snapbean, soybean, tobacco, and tomato.

Symtoms      

The first symptoms of black root rot include yellowing and marginal scorch of the foliage. Later, twigs or stems may die back and eventually the entire plant may die. The root system of the declining plant is stunted and decayed. Black lesions on the infected roots contrast sharply with the adjacent healthy white portions. Lesions may appear on the tips of feeder roots or elsewhere along the root.

Cause And Spread      

Black root rot is caused by Charlara elgans (formerly Thielaviopsis basicola). This fungus can persist indefinitely in the soil or it can survive as a saprophyte on plant debris.

Control

1. Plant only disease-free plants in the landscape. We have observed that some container-grown blue hollies shipped from out-of-state sources were already infected with the black root rot fungus. This means it is very important to examine root systems prior to planting in the landscape. If blackened roots are evident, the presence of C. elgans can be confirmed through microscopic examination or laboratory assay.

2. Avoid planting susceptible plants in soils known to be infested with the fungus. While the fungus is widespread, it may be present in higher levels in soils where black root rot was previously a problem on other crops, such as tobacco. When these old agricultural lands are developed for housing, homeowners may find they have also purchased a black root rot problem as well. In many cases, of course, it is not possible to have this type of knowledge beforehand.

3.In the landscape, badly infected plants should be removed and the site replanted with a non-susceptible host.

4. There are no effective fungicide drenches available for controlling black root rot in the landscape. Steam pasteurization or fumigation with methyl bromide will eradicate the fungus from propagating and growing media in nurseries. Some fungicides, such as Banrot, are registered for controlling this disease in greenhouses.

5. In the case of hollies, some nursery workers and researchers have observed that good cultural practices may enable some plants to continue to grow in spite of the disease. Plants in the early stages of infection should be well fertilized and watered.

A Strobilurin Fungicide with A Broad Label for Landscape Plants

by John Hartman, Extension Plant Pathologist

Although the strobilurin fungicide Heritage, marketed by the Zeneca Company, has been available for managing turfgrass diseases for a couple of years, this is the first season it has been available to the professional landscape industry for ornamental plants as well.  Some County Extension Agents and landscape managers have inquired to learn to which plants and for which diseases this fungicide might be used effectively.  Although Heritage may be used in the home landscape by professionals, it does not appear to be packaged for routine homeowner use.

What are strobilurins?  Strobilurins are naturally occurring fungicides produced by various species of wood-decaying mushrooms, including Strobilurus tenacellus and Ouidmansiella mucida.  These mushrooms produce strobilurins to eleminate other fungi from competing with them for nutrients.  One of the trobilurins, azoxystrobin, was selected as the active ingredient for Heritage fungicide.  This is the first of what may eventually be several fungicides in this class available for control of landscape plant diseases.  All of these natural product-derived fungicides are considered reduced-risk fungicides in that they present little risk to off target species and to the environment.

How does azoxystrobin affect diseases?  This fungicide blocks fungal spore germination and infection of the plant.  It provides curative activity against certain diseases after infection and it blocks spore production.  The fungicide can enter the plant through the foliage or be taken up by the root system.  It then moves through foliar tissues and systemically throughout the plant.  In some circumstances, the fungicidal effect may last up to 3-4 weeks.  Although it does not control all diseases, it does affect a broad spectrum of fungal pathogens.

Selected Plants and diseases for which Heritage is labeled.  The following plants and diseases were selected from the recently-issued supplemental label for Heritage:

Roses - black spot, powdery mildew, downy mildew, rust, and two other leaf spots. 

Dogwood - powdery mildew and leaf spots and blights. 

Oaks - powdery mildew and leaf spots. 

Rhododendrons - powdery mildew, Phytophthora blight, soilborne diseases, anthracnose. 

Juniper - Phomopsis tip blight and cedar rusts. 

Pine - Sirococcus tip blight and rust. 

Aster, Hemlock - rust.

Lilac - powdery mildew.

Geranium - rust, gray mold, powdery mildew.

Also fungal diseases of abelia, arbor vitae, artemesia, buddleia, clethra, crapemyrtle, chrysanthemum, English ivy, euonymus, fig, forsythia, foxglove, holly, hosta, Japanese maple, liriope, magnolia, nandina, primrose, privet, pothos, ornamental grasses, ornamental pear, river birch, rose-of-sharon, rudbeckia, sedum, viburnum, vinca, wiegela, and many other plants. 

Cautionary note.  Do not apply Heritage fungicide to certain apple, crabapple, or cherry trees due to possible phytotoxicity.  Further, do not use spray equipment that has applied Heritage fungicide for use in these sensitive crops due to possible phytotoxicity from residue remaining in the sprayer.  Thus, one of our most disease-prone landscape plants, flowering crabapple, should not be treated with Heritage.  This notice is especially important for Kentucky apple growers who might be using the same sprayer for nursery stock.  We have also made growers aware that the fungicides Quadris and Abound, two other strobilurins with the same active ingredient, are phytotoxic to many apple varieties.  Follow label directions for application and resistance management instructions.

Fall Webworms

By Lee Townsend, Extension Entomologist

The fall webworm feeds on almost all shade, fruit and ornamental trees except for evergreens.  In Kentucky some of  the preferred trees include mulberry,  American elm, maples, hickory, and sweetgum.  Their tents are spun on the end of branches and there is usually more than one generation each year.

The fall webworm caterpillar is about one inch long, very hairy and is pale green or yellow.  They may have either a red or black head. The blackheaded larvae have black spots along its back while the redheaded haveorange to reddish spots.  The blackheaded larvae will create a flimsy web while the redheaded makes a larger, more dense web.

Destroying the tents is an effective way of getting rid of the caterpillars on small trees.  It is best to do this around dusk or early morning when the larvae are in the tent.   If an insecticide is used, treat when the larvae are small and easiest to control, not when they are full grown and have already done their damage.  Insecticides containing the active ingredient derived from Bacillus thuringiensis are the best choices for safety and selectivity. This is a stomach poison, which must be ingested by the caterpillars.  Treat foliage around the nest area.  Applications to the tent or insects will not be effective. Do not burn the tents because the fire and intense heat may damage the tree or start a larger fire.  Generally, there is no reason to control this insect on large, established trees.

Maples Continue To Die In the Landscape

by John Hartman, Extension Plant Pathologist

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

The diagnostic laboratory cannot diagnose girdling roots, mechanical injury, root rot, and usually Verticillium wilt with a sample consisting of some twigs, leaves, and small branches.  However, site visits and perceptive questions of the growers are most useful, and for cases of mechanical injury, girdling roots, and inadequate planting site, would be more informative than a laboratory specimen.

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:

Girdling roots are probably the leading cause of decline, especially among Norway maples.  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 can be suspected.  Trees with girdling roots may decline over a period of years, but then may collapse suddenly.

Verticillium wilt may infect all types of maples, and can also cause disease in tuliptrees, catalpas, golden-rain trees, and redbuds.  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.

Canker and collar rot.  We have diagnosed some cases of Phytophthora bleeding canker and collar rot on maples in past years.  Trunks of affected trees have water-soaked bark spots.  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 should not be a factor this year due to the mild winter.

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 trees 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, dry spring conditions, mild winter temperatures, drought late 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 leaf scorch, premature fall color, and branch tip dieback.

Mealybugs

James R. Baker, Extension Entomologist, North Carolina Cooperative Extension Service, North Carolina State University (Revised April 1998)

Female mealybugs are soft oval insects without wings. They are up to 3 mm long. Some species are covered with fluffy wax and others have long, tails of fluffy wax.

Male mealybugs are tiny, gnatlike insects with two wings and long tails of white wax.

Mealybug eggs are very small but are covered by a conspicuous dense, fluffy, white mass of wax called the ovisac.

Very young nymphs are flat, oval and yellow. Older nymphs of some species are covered with fluffy, white wax.

Biology

Mealybugs are pests of ornamental crops indoors and outdoors across the world. They are most active in warm, dry weather. Most species of ornamental plants can be infested with mealybugs. Mealybugs damage plants by inserting their threadlike mouthparts into any part of the plant and sucking out sap. Mealybugs excrete honeydew, a sweet, sticky liquid. Sooty molds often grow in the honeydew causing infested plants to turn black. Heavily infested plants are disfigured by the mealybugs, their ovisacs, honeydew and sooty molds.

Female mealybugs have no wings and must be transported directly to or near the next host plant. They can travel short distances by crawling or the very young nymphs may be blown about by the wind or carried on the feet of birds. Small numbers of mealybugs are easily overlooked, as they tend to wedge into crevices on plants. Mealybugs are usually found at the base of stems (or petioles of plants with long petioles such as African violets). After the first batch of eggs hatch, the infestation becomes very noticeable. As their numbers increase, mealybugs of all sizes can be found crawling around or feeding on all surfaces of the plant.

Each female usually lays from 200 to 600 eggs in the thick ovisac. Some species of mealybugs give birth to live young. After several weeks, the nymphs develop into adults. Male nymphs secrete a tiny, fluffy cocoon and develop into winged adults. Males then fly about seeking females to mate with.

Control

Mealybugs are not easy to control. Because the eggs are enmeshed in the waxy fluff, it is difficult to get a pesticide through to kill them. Treatments may have to be repeated two or more times at weekly intervals since new mealybugs hatch from egg masses which might have been missed by the spray.

Pesticide  (TradeName)           Formulation and Amount

*acephate   (Orthene)                            OUTSIDE ONLY 9.4% emulsifiable concentrate: 3 tablespoons per gallon of water

 *acephate              (Orthene)               76% 1 to 2 teaspoons/ gallon of water

 azadirachtin(Azatin XL, Neemazad) 3 and 4.5% emulsifiable concentrate: 2/3 tsp and 1/8 to 1/4 tsp/gallon of water

bendiocarb(Ficam,Dycarb)      76% wettable powder: 3/4 tsp/ gallon of water

bifenthrin (Talstar)                10% wettable powder: 1 to 5 tsp/gallon of water

*carbaryl  (Sevin)                   40% flowable liquid: 1 tbls/ gallon of water

*carbaryl (Sevin)                   50% wettable powder: 2 tbls per gallon of water

*chlorpyrifos(Dursban)           OUTSIDE ONLY 6.7 % emulsifiable concentrate: 1/2 to 1 tsp/ gallon of water

chlorpyrifos(Duraguard)          20% microencapsulated liquid: 8 tsp/gallon of water

cyfluthrin (Decathlon)           20% wettable powder: 6 tbls / 100 gallons of water

fenpropathrin  (Tame)             30%emulsifiable concentrate: 2/3 tsp/ gallon of water

*fluvalinate  (Mavrik)             23% aquaeous flowable: 1/8 to 5/8 tsp/ gallon of water

kinoprene (Enstar II)             65.1% emulsifiable concentrate: 1/2 to 2/3 tsp / gallon of water

*malathion                           50 to 57% emulsifiable concentrate: 2 tsp / gallon of water

*oil (horticultural or summer)  98 to 99% emulsifiable concentrate: 8 tsp / gallon or water

permethrin (Astro)                 36.8 emulsifiable concentrate: 1/4 to 1/2 tsp / gallon of water

*pyrethrins (Pyrenone)          6% emulsifiable concentrate: 1/8 to 1 1/2 tsp per gallon of water

 *soap (M-Pede, Olympic, Safer's Insecticidal Soaps)  - 50.5% emulsifiable concentrate: 2 to 5 tbls / gallon of water

Gypsy Moth Trapping Update

The gypsy moths flew earlier this year than in years past.  The first moth was captured the first week of July.   Following is a summary of the counties where gypsy moth has been caught to date, the number of moths caught, and if the trap caught a single moth or more than one.

County                Moths                 Trap Count        

Jefferson             2                         Singles

Greenup               3                         Singles

Bracken               27                       Singles

Owen                   3                         Singles

Boyd                   27                       6 Multiples

                                                       5 Singles

Kenton                3                         Singles

Boone                 1                         Singles

Madison              1                         Singles

Fayette                1                         Singles

Gallatin               6                         1 Multiple                                                                  4 Singles

Surplus trees and shrubs offered for sale by UK through sealed bids.

Invitation to Bid.  Sealed bids will be accepted by the University of Kentucky's Horticulture Dept., N-324 Ag. Science North, Lexington, KY 40546-0091 no later than 3:00 pm on Sept.7, for field-grown surplus trees (1"-3"caliper) and shrubs (3'- 6') (red oak, white ash, red bud, hawthorn, lilac, viburnum, fir, taxus) in whole blocks.   The plants are located on the UK Horticulture Research Farm at the corner of Man O War Blvd. and Nicholasville Road in Lexington.  For bid information call (606) 257-1601.