JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

Janet Lensing hanging a wing trap for oak pests at Lake Barkley State Park

University of Kentucky Department of Entomology Office of the State Entomologist S-225 Ag Science Ctr—N Lexington, KY 40546-0091 Phone: (859) 257-5838 Fax: (859) 257-3807

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https://www.facebo

ok.com/KyStateEnt

SPRUCE SPIDER MITE

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JAPANESE MAPLE SCALE PAGE 4

AMBROSIA BEETLE PAGE 7

INSPECTOR FINDINGS IN KENTUCKY

JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

Spruce Spider Mite Injury Appearing By Lee Townsend, Extension Entomologist

Spruce spider mites (SSM), like other plant-feeding mites, use piercing sucking mouthparts to feed on sap. Feeding from individual cells initially produces small, yellow splotches on needles. Over time, the needles take on a dull, rusty appearance and some may drop prematurely. In addition to feeding on their namesake host, spruce spider mites can thrive on over 30 conifers, including juniper, yew, and arborvitae. SSM do best while temperatures are in the 60oF to 70oF range, so this spring as been favorable for them and symptoms are beginning to appear on infested trees. In many cases, infested trees and shrubs do not exhibit obvious symptoms until mite numbers are very high. SSM will feed and their numbers will increase until daily high temperatures begin to hit and stay in the mid- to upper 80s, after which their activity subsides until resurgence in fall.

! Figure 1. Needles show a reddish brown discoloration due to feeding by spruce spider mite.

(Photo: Lee Townsend, UK)

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JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

Detection Preventing extensive visible damage by SSM depends on detecting infestations before symptoms become obvious. The small size of mites makes this challenging. Hold a white piece of paper under a branch while striking or shaking it vigorously 4 to 5 times to dislodge mites that may be present. Count slowly to 10, before pouring off needles and debris. Then, examine the paper carefully for the tiny olive green mites.

Mite Control Insecticidal soap, applied with thorough coverage, can provide good control. Check the label for precautions; soaps can temporarily remove the blue bloom from spruces. Repeat the sampling process about 3 days after the application to see if an additional treatment is needed.

Herbicide Damage?

This website from the University of California could help you identify herbicide damage on

different plants.

Visit herbicide symptoms.ipm.ucanr.edu

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JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

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Integrated Pest Management for Commercial Horticulture

ipmnet.umd.edu Pest Alert - 2012 (Revised)

Japanese Maple Scale (Lopholeucaspis japonica):

A Pest of Nursery and Landscape Trees and Shrubs

Introduction

Over the past several years the exotic Japanese maple scale (JMS), Lopholeucaspis

japonica (Cockerell) (Hemiptera: Diaspididae), has become a pest insect of major concern to nursery crop producers and landscape managers in MD and the eastern U.S. JMS is difficult to control and monitor due to its wide host plant range (over 45 genera of plants in 27 families), extended crawler emergence period, and its small size and somewhat cryptic coloration. Unless monitored carefully and controlled early, populations of this armored scale can spread throughout a nursery or landscape to many species of woody plants and build up to levels that cause dieback and even death of infested plants. The first U.S. detection of JMS was in CT in 1914 (Miller et al. 2005), and it has since been reported in Washington DC, and 15 states (AL, DE, GA, IN, KY, LA, MD, NC, NJ, NY, OH, PA, RI, TN, and VA) (Miller and Davidson 2005). JMS is not a quarantine pest on the east coast but several states in the mid-west have quarantines on JMS and states known to receive infested plant material have rejected shipments. Identification In The Field JMS is a member of the armored scale family Diaspididae. The presence of a waxy cover that is not attached to the soft body underneath is a good field characteristic to distinguish armored

scales from other families of scales. JMS is one of the smaller armored scale pests of ornamentals with adult female covers only ~1 mm in length. The cover of JMS is irregularly oystershell shaped. Adult females have a thicker, dark brown cover (pupillarial) that is the enlarged second-instar shed skin that is entirely covered with white wax. When the white wax is rubbed, or treated with oil, the brown cover appears. Since the newly formed outer cover is white, this pest is relatively easy to see on dark bark plants but harder to see on trees with light bark. The male and female covers look very similar.

Female without wax covering

Heavy infestation on maple bark

Japanese maple scales with wax covering

JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

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Eggs, soft bodied immatures and adult females under the wax covers are usually light purple, sometimes yellow-white in color. Newly emerged crawlers are extremely small, oval, and purple. Within hours of emergence crawlers settle on the wood and begin to produce a light covering of white wax (settled crawler). JMS is normally on the bark, both trunk and branches, of host trees but in heavy infestations have been observed on leaves.

Life CycleThe limited published literature on JMS indicates there is one generation per year in cold climates such as Northern Japan and Pennsylvania, where fertilized females overwinter. In warmer climates such as Maryland and Virginia, two generations per year with second instar males and females overwintering were reported (Miller and Davidson 2005). Research in MD conducted in the last two years (2009, 2010) has further examined the life cycle of JMS. Studies confirmed in Maryland that JMS has two generations per year and overwinter as immature 2nd instar males and females. In the spring, JMS continue to develop and mate. Adult females with eggs are seen

in late April to early May. Egg laying and crawler emergence periods extend over long periods of time (see table) making management of JMS challenging. The table below lists crawler activity period, and the Degree Day (DD) accumulations (using base 50°F from Jan. 1; averaged over 4 years for 1st generation crawlers and 2 years for other DD estimates) for the beginning of crawler activity and peak crawler activity. These degree days occurred around mid May / early June for 1st generation and August for 2nd generation.

Cotinus coggygrias (Smokebush) and Syringa chinensis (Chinese lilac) were in full bloom at the time of first generation crawler activity and can be used as phenological indicators. Aralia spinosa (devil’s walkingstick) was in bud at the time of second generation activity.

Damage and MonitoringScales are sucking insects that remove plant sap. High populations can cause premature leaf drop,

branch dieback, and ultimately tree death. In addition, white scale covers that accumulate on the bark and branches of plants often remain for a period of time following control measures, are unsightly,

Purple crawler

Purple eggs under female cover

Defoliation from JMS

1st Generation 2nd GenerationStart(DD)

Peak(DD)

# WeeksActive

Start(DD)

Peak(DD)

# Weeks Active

806 1144 7.5 2220 3037 8.5

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The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied.

Read labels carefully before applying any pesticides.

University of Maryland Extension programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status, or national origin.

June 2012

and have led to rejection of plant shipments. Monitor

potential hosts closely for JMS and try to identify

infestations early. Examine plants showing any level

of leaf loss or dieback. Light infestations often start in

the cracks and rough areas of the bark and branches.

Look on bark for the small white, elongate, narrow

scale covers. To determine if the scale is JMS gently

rub the white wax to expose the underlying dark

brown second instar shed skin, and using a hand

lens or microscope squish or flip off the scale covers to look for signs of the purple soft bodied insect or

eggs. When nearing the appropriate DD for crawler

activity closely monitor for signs of crawlers. Look

for discrete circular holes in scale covers that indicate

parasitoids are attacking the JMS population.

ManagementMechanical: Use a high pressure water spray or

gentle scrub brush with water to remove scale covers

from trunks of trees to improve aesthetic appearance

and/or reduce populations. Prune out dead branches

with scales.

Chemical: Dormant applications of horticultural

oil should be applied at 2-3% rates in the fall after

leaves drop or in spring before bud break. If applying

in fall or spring, apply when temperatures are above

50-60 °F for 4 to 5 days. During the growing season

target the crawler stage for optimal control. See the

degree day crawler activity table above. Horticultural

oil at a summer rate of 2.0 % can be applied when

crawlers and early instars are present. Do not apply

horticultural oils to drought stressed plants. When

crawlers and early instars are present and at peak

activity, one of the two insect growth regulators

(IGRs), pyriproxyfen (Distance) or buprofezin

(Talus) can be applied. The addition of 0.5 or 1%

horticultural oil has been shown to improve coverage.

The IGRs will prevent the crawlers or early instar

stage from developing into the next instar stage,

resulting in death of the insect. IGRs are slow acting

so be patient. Two to three applications may be

necessary. Studies at UMD have evaluated two

systemic neonicotinoid insecticides, dinotefuran

(Safari, Transtect) and clothianidin (Arena). Arena

provided faste and somewhat greater control than

Safari. Systemics should be applied at the very first sign of crawler activity and should provide control

of 1st

and 2nd

generation JMS. Arena is labeled for

landscape use only, Safari is labeled for landscape

and nursery use. Follow use limits on the label. Read

and follow the label directions of pesticides carefully.

ReferencesJohnson, Warren J., and H.H. Lyon. 1991. Insects that Feed on Trees and Shrubs – Second Edition, Cornell

University Press

Miller, Douglass R., and J.A. Davidson. 2005. Armored Scale Insect Pests of Trees and Shrubs. Cornell University

Press

Miller, Douglass R., G.L. Miller, G.S. Hodges, and J.A.

Davidson. 2005. Introduced Scale Insects (Hemiptera: Coccoidea) of the U.S. and their Impact on U.S. Agriculture. Proc. Entomol. Soc. Wash. 107 (1): 123-158.

Japanese Maple Scale (Lopholeucaspis japonica): A Pest of Nursery and Landscape Trees and Shrubs

byStanton Gill, Extension Specialist, IPM for Nurseries and Greenhouse, Central Maryland

Research and Education Center, University of Maryland Extension, Ellicott City, MD, sgill@umd.edu

Paula Shrewsbury, Extension Specialist, Department of Entomology, University of Maryland,

College Park, MD, pshrewsb@umd.edu

John Davidson, Professor Emeritus, Department of Entomology, University of Maryland,

College Park, MD

JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

Ambrosia Beetles Are Different By Lee Townsend, Extension Entomologist

Bark beetle and shot hole borer are general terms used for a large group of small beetles that chew round holes, usually in dead or dying trees and woody ornamentals. These insects inhabit the phloem layer or where bark and sapwood meet. They create characteristic tunnels or galleries in the wood, which disrupt water and nutrient flow. Ambrosia beetles are different in several respects. 1 They bore deep into sapwood. 2 Females carry fungal spores with

them that germinate within the tree, providing food for larvae and adults.

3 While most species attack stressed or dying plants; a few enter apparently healthy ones. This combination presents significant problems. A good example is Asian (granulate) ambrosia beetle, which can live in over 200 species of trees and shrubs.

Management • Preventive bark sprays with insecticides are not particularly effective in

preventing infestations. • Heavily infested trees/shrubs should be removed and destroyed. • A sound plant health program that includes practices such as optimum

fertility, reduction of environmental stress when practical, and watering as needed, will help to reduce problems with borers.

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Figure 1. Sawdust “toothpicks” of ambrosia beetle in Wisteria. (Photo: G. Hardin)

JUNE 2015 OFFICE OF THE STATE ENTOMOLOGIST VOLUME XVIII, ISSUE III

What To Look For

John Obrycki, Ph.D: State Entomologist

Joe Collins: joe.collins@uky.edu Pest surveys & nursery licenses

Carl Harper: carl.harper@uky.edu Slow-the-Spread gypsy moth trapping coordinator, phytosanitary certificates

Katie Joya: katie.joya@uky.edu Pest surveys, nursery inspections, newsletter editor

Jennie Condra: jennie.condra@uky.edu Outreach coordinator, nursery inspections, pest surveys

Janet Lensing, PhD: janet.lensing@uky.edu State Survey Coordinator

JD Loan: jdloan.1@juno.com Survey supervisor

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