TPM/IPM Weekly Report
for Arborists, Landscape Managers & Nursery Managers
Commercial Horticulture
In This Issue...
- Ambrosia beetles
- Japanese maple scale
- Boxwood leafminer adults
- Woolly aphids on hawthorn
- Aphids
- Spiny witchhazel gall aphid
- Hemlock woolly adelgid
- Boxwood psyllids
- Euonymus leaf-notcher
caterpillar
- Eastern tent caterpillars
- Abiotic issues
Beneficial of the Week
Weed of the Week
Plant of the Week
Phenology
Degree Days
Announcements
Pest Predictive Calendar
IPMnet
Integrated Pest
Management for
Commercial Horticulture
extension.umd.edu/ipm
If you work for a commercial
horticultural business in the
area, you can report insect,
disease, weed or cultural
plant problems found in the
landscape or nursery to
sklick@umd.edu
April 22, 2016
Coordinator Weekly IPM Report:
Stanton Gill, Extension Specialist, IPM for Nursery, Greenhouse and Managed
Landscapes, sgill@umd.edu. 301-596-9413 (office) or 410-868-9400 (cell)
Regular Contributors:
Pest and Beneficial Insect Information: Stanton Gill and Paula Shrewsbury
(Extension Specialists) and Nancy Harding, Faculty Research Assistant
Disease Information: Karen Rane (Plant Pathologist) and David Clement
(Extension Specialist)
Weed of the Week: Chuck Schuster (Extension Educator, Montgomery County)
Cultural Information: Ginny Rosenkranz (Extension Educator, Wicomico/
Worcester/Somerset Counties)
Fertility Management: Andrew Ristvey (Extension Specialist, Wye Research &
Education Center)
Design, Layout and Editing: Suzanne Klick (Technician, CMREC)
Ambrosia Beetles
By: Stanton Gill
We are setting up trials to evaluate the use of alcohol detectors on nursery
trees. This testing is the first stage in the development of determining what
trees may be susceptible to attack by ambrosia beetles. Our Maryland trial is
on trees growing in the ground. Chris Ranger, USDA, is conducting trials in
Ohio on container grown trees. Chris is comparing alcohol levels of trees that
receive heavy doses of water compared to trees held on the drier side. Our
goal is to develop a practical field method of determining which trees are at a
higher risk of damage from ambrosia beetles.
The following are the two updates sent out via email this week.
Ambrosia Beetle Activity Is On the Upswing (April 18)
From: Stanton Gill, sgill@umd.edu
I received an email this morning form a nursery in Montgomery County
reporting yellowwood trees with fresh sap on the trunks. Their alcohol traps
had lots of beetles and they are submitting them to us for ID. I examined
samples from our CMREC traps and ones from James Becker who is
sampling with the Chestnut Society at Ft. Detrick in Frederick County. Our
trap catches at CMREC had 23 Xylosandrus germanus. The samples form
Ft. Detrick had 2 Xylosandrus crassiusculus. These species are the ambrosia
beetles we are concerned about that can damage nursery and landscape trees.
It is predicted to reach 80 °F today and stay warm through the week. I
think it is finally time to pull the trigger if you are going to apply either
permethrin or bifenthrin (Talstar) to the trunk of susceptible species.
Styrax, yellowwood and redbud would be high on my list of susceptible
trees.
Mid-Week Ambrosia Beetle Update (April 20)
From: Stanton Gill
We received confirmation from Marie Rojas in Darnestown and Steve
Dubik in Frederick that they are finding dogwood and styrax that are
actively being attacked by ambrosia beetles this week.
On Tuesday, late in the day, I examined alcohol trap samples from Union
Bridge (Carroll County) and Gaithersburg (Montgomery County) and
both trapping sites have Xylosandrus germanus in fairly large numbers
in their trap catches.
To monitor for Xylosandrus ambrosia
beetles, look for wet areas and
One note - As you apply the pyrethroids to the trunk of trees to be
developing frass tubes on tree trunks
protected, try to use low pressure and do not use an air blast sprayer that
slops the pesticide all over the nursery or landscape. The pyrethroids are very hard on predators and parasites.
So, the objective is to direct the spray just to the trunk and main branches to minimize impact on beneficials.
Japanese Maple Scale – Interesting Developments
By: Stanton Gill
We are conducting trials in 2016 to evaluate two systemic
insecticides for Japanese maple scale control. As part of this
trial we had to examine branch samples heavily infested with
Japanese maple scale. In the majority of the cases, Japanese
maple scale overwinters as 2nd instar males and females which
mature into third instar mature females and pupating males in
late May to early June.
When we were taking the pre-treatment counts we found
5 adult males and 8 mature females. I am not sure if the
unusually warm fall which extended into late December sped
up the development or some other factor has come into play
here. I sent pictures of the adult male to John Davidson for
confirmation and he felt they were male JMS.
I will look at samples from several other sites and see if the
ones we looked at were an oddity or whether we had a partial
generation try to come out during the warm weather last fall.
This adult male was found on samples heavily
infested with Japanese maple scale (JMS); the
tentative identification is a JMS adult male
Boxwood Leafminer Adults
By: Stanton Gill
Paul Wolfe, Integrated Plant Care, called in to report heavy adult boxwood leafminer activity in Bethesda on
April 20. If you are going to try to control adults now appears to be the time in central Maryland.
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Woolly Aphids on ‘Winter King’ Hawthorn
By: Nancy Harding, UMD
At first glance you might mistake the purplish/red and curling leaves on this Crataegus viridis ‘Winter King’
as winter damage since so many other landscape plants this year have had winter injury. However, if you take
a closer look by unfurling the leaf you will probably discover early instars of woolly aphids. The images below
show the distortion damage and wooly aphids (indicated by black arrow) that were found on April 18 in Bowie.
In addition, these sucking phloem-feeding aphids produce a sticky, sweet by-product called honeydew. Ants find
honeydew irresistible and are often associated with woolly aphid infestations. The accumulated degree days in
Bowie on April 18 were 188DD.
Control: Heavy infestations of woolly aphids rarely occur as their numbers are kept low with natural predators
like lacewings, lady beetles, hover flies, parasitic wasps, and birds. Goldfinches commonly feed on these aphids.
Look for signs of parasitized aphids - they stop producing wax and become discolored (mummified). A circular
exit hole made by the parasitoid can sometimes be seen in the aphid mummy’s upper surface. However, if large
infestations occur, horticultural oil or insecticidal soap sprays can be used in the spring.
Hawthorn ‘Winter King’ showing curled leaf from aphid feeding (on left). On the right is a woolly aphid (black
arrow) with protector ant (red arrow).
Photos: N. Harding, UMD
Aphids
Jessica Frakes, Thrive Inc., found aphids on hawthorn in Alexandria, VA, and on roses and hydrangeas in NW
D.C. this week. Look for honeydew, sooty mold, and aphid cast skins on foliage. Also look for high ant activity.
The ants protect the aphids from predators and feed on the honeydew secreted by the aphids.
Control: If present in the landscape, syrphid fly larvae, lady bird beetles and lacewing larvae are good predators
of aphids. Insecticidal oil and horticultural soap can be used and have minimal impact on beneficial insects.
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Aphid activity is
increasing as leaves
emerge on woody
and herbaceous
plants
Photos: Jessica
Frakes, Thrive, Inc.
Spiny Witchhazel Gall Aphid
Marie Rojas, IPM Scout, is reporting that spiny witchhazel gall aphids
are feeding on the undersides of newly emerging birch leaves in
Frederick County. Look for spiny witchhazel gall aphids and damage
on witchhazels and birches in the next few weeks. This aphid causes
red puckering damage to the foliage of birch and the woolly aphids
can be found on the undersides of the leaves. It causes spindle galls
on its alternate host which is witchhazel.
Control: Most often, control is not necessary. Many natural enemies
such as lady bird beetles, syrphid flies and parasitic wasps are active
this time of year and usually move into the area to reduce the aphid
populations. If populations are high, use a low impact material like
horticultural oil to minimize the effect on the beneficial insects that
Look for red puckered foliage on birch
are present.
caused by the spiny witchhazel gall aphid
Hemlock Woolly Adelgid
By: Stanton Gill
George Mozal, Stanbury Tree, and Paul Wolfe, Integrated
Plant Care Company, called in to report hemlock woolly
adelgid hatch this week. Paul reported it in Bethesda.
George reported crawler activity in Reston, VA. Marie
Rojas, IPM Scout, is finding eggs, but no hatching yet,
within the fluffy egg masses in Beallsville. Look for
reddish crawlers as they emerge from the white egg sacs.
There is a second generation of crawlers in late summer.
Control: 2% horticultural oil is one low risk material that
can be applied to control the crawler stage that is active
Look for activity of reddish hemlock woolly adelgid
crawlers as they emerge from the white egg sacs
this week.
Boxwood Psyllids
Jessica Frakes, Thrive Inc., found boxwood psyllids active this week in Virginia. Look for new leaves starting to
become distorted. Pull the leaves apart and look for white wax and active nymphs.
Control: The damage is very insignificant in that it only causes new growth to cup slightly so control is usually
not necessary. If populations are high, a systemic insecticide would provide the best control.
Within the cupped foliage (left), look for the
green, waxy coated psyllid (above)
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Euonymus Leaf-notcher Caterpillar
Jody Fetzer, Montgomery Parks, sent an email reporting late instar euonymus leaf-notcher caterpillars active in
Reston, VA on April 15. In Maryland, this caterpillar has been reported in Anne Arundel, Prince George’s and
Baltimore counties.
Control: Since the damage occurs early in the season, control is not always necessary. There is only one
generation of this pest and plants can recoup. If you decide to treat, control options include Conserve (spinosad),
Talstar (bifenthrin), and Orthene (acephate).
Eastern Tent Caterpillars
Eastern tent caterpillars continue their tent expansion and feeding.
Marty Adams, Bartlett Tree Experts, noted this
eastern tent caterpillar infestation is the worst he has
seen. Silk web trails are covering the trunk of this
cherry in Baltimore and at its base on the ground
Photos: Marty Adams, Bartlett Tree Experts
Brian Scheck, Maxalea, Inc., photographed this large tent of
eastern tent caterpillars on a cherry in Pikesville
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Abiotic Issues
When Mark Schlossberg sent in this photo of a boxwood
planting in Timonium, he noted that “other than the orange
color, they look fine”. Some boxwood plants turn orange in
winter when planted in full sun.
Photo: Mark Schlossberg, ProLawn Plus, Inc.
Ginny Rosenkranz, UME, photographed this
hosta that was damaged from the recent
frost
Beneficial of the Week
By: Paula Shrewsbury, University of Maryland
Chinese praying mantises are hatching!
It is that time of year when days are getting
longer and temperatures warmer. We are
seeing more insect activity every week! Last
fall, female praying mantises attached their
ootheca (egg case) to the stems of various
plants. It is in the egg stage that mantids
spend the winter. A few weeks ago I found
an ootheca of the Chinese praying mantis
in my yard and have been observing it ever
since. The ootheca is round and brownish in
color, about ¾” in diameter, and feels like a
lightweight ball of styrofoam (see image).
Each ootheca can have 100 to 200 eggs in it.
Chinese mantis ootheca (egg mass) with newly emerged nymphs.
Photo: P.M. Shrewsbury, UMD
To see a video of the mantises emerging go to: https://www.
youtube.com/watch?v=2yVcS794btI
Last Monday, April 18, I went to check on
the ootheca and was pleasantly surprised!
Praying mantid babies were starting to
emerge from the ootheca! As you can see from the image there is a mass of mantises hanging off the side of the
ootheca. The nymphs wriggle their way out of the egg case and look almost worm-like. They hang off of silk
and each other as they begin to expand their bodies. Blood and air are pumped through the body as their legs,
6
antennae and other body parts become more distinguishable. They are light colored for a few hours until their
exoskeletons harden off. I would estimate over 100 little mantises emerged. You can view a YouTube video of
the mantis emerging from the ootheca at: https://www.youtube.com/watch?v=2yVcS794btI. Chinese mantis
adults are a bright green color and can reach 4-5” (see image). Mantises are carnivorous and the first instar
Chinese mantis will feed on small prey items like aphids or flies. As they get bigger they consume larger prey
items. They are sit-and-wait predators. They will sit very still on a plant and when a prey item comes close, the
mantis will pounce on the prey and grab it with it raptorial legs. Interestingly, it seems the mantis often starts
to feed on the head end of its prey. Mantises are voracious predators and feed on a wide range of insects and
spiders, some of which are pests of our plants, others are not. Having mantises and mantis egg cases on plants in
your property is an indication of a healthy ecosystem.
Chinese praying mantis adult female. Image taken in
the fall. Note the large abdomen indicating she will
soon be laying eggs.
Photo: M. J. Raupp, UMD
Newly emerged Chinese mantis nymph that has not
expanded its body yet
Photo: P.M. Shrewsbury, UMD
Weed of the Week
By: Chuck Schuster, University of Maryland Extension
Soil temperatures continue to rise, rather quickly at the beginning of the week with the warmer weather, and
now slightly slower. There have been consistent 48 °F readings in Central Maryland, with the lower shore
seeing soils in the low to mid 50 °F range. The weeds are really off and running for the season. Soils are dry
in many areas which will affect the efficacy of many pre-emergent herbicides as they require moisture for
activation. Rain is in the forecast in some areas for the week’s end.
Shepherd’s purse, Capsella bursa-pastoris, is an invasive winter annual weed in the Mustard family. It grows
from a ground hugging four to a tall twenty-five inches in total height from a basal rosette. Basal leaves are
lance-shaped and up to two and one half inches in length. Stem leaves are alternate, clasping, lance-shaped,
narrow, and toothed. The white to pink flowers have four petals and are found on thin spreading stalks that
produce heart-shaped, flat seed pods. Each pod can contain up to twenty seeds. Shepherd’s purse reproduces
only by seed. Seeds require disturbance for germination and will survive long periods in the soil.
This plant prefers dryer climates but can survive on wet sites. The name for this weed comes from the small flat
seeds that are produced, triangular in shape, with a seam in the middle.
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Cultural control in turfgrass includes appropriate mowing height, pH and fertility management. Strong turf is
an excellent deterrent to this weed. In garden settings, control it using mulch or other barriers, mechanical hand
removal or flaming. Use caution with flaming as it can cause fires with the extremely dry conditions that are
currently being experienced.
Shepherd’s purse will respond to pre-emergent applications of oryzalin (Surflan), Snapshot, and Dichlobenil
(Casoron). Post-emergent control may be obtained using several selective broadleaf herbicides labeled for turf,
and nursery. In landscapes this weed can be controlled with many of the non-selective translocated products.
Shepherd’s purse only reproduces by seed
Photos from PLU NCSI with permission
Plant of the Week
By: Ginny Rosenkranz, University of Maryland Extension
Magnolia soulangiana, saucer magnolia,
is a lovely deciduous spring blooming
magnolia that is very cold tolerant,
growing in USDA zone 4-8. There
are many cultivars available including
the Little Girl series developed by the
National Arboretum which includes
‘Ann’, ‘Betty’, ‘Jane’, ‘Judy’, ‘Pinkie’,
‘’Randy’, ‘Rickie’ and ‘Susan’. This series
blooms later in the spring than the species
by about 2 weeks to reduce the possibility
of frost damage. Magnolia soulangiana
‘Jane’ grows 10-15 feet tall and 8-12 feet
wide but will begin to bloom when only
2-3 feet tall. Flower buds are light tan to
silver gray and silky to the touch, creating Magnolia soulangiana ‘Jane’ is deep pink in bud and opens to show
the white on the inside of the petals
an interesting look in winter and very
Photos: Ginny Rosenkranz, UME
early spring. The flowers open before the
leaves emerge and are large cups almost 8 inches in diameter. When the flowers first bloom in April to May, the
dark reddish purple color is bright against the soft silver gray bark, but as the flowers open it is easy to see that
the petals are dark on the outside and white on the inside. The oval-shaped leaves begin with copper red tints
in early spring then expand to about 6 inches long and dark green in color in the summer, eventually changing
to bronze copper to yellow hues in the autumn. Magnolia soulangiana ‘Jane’ grows and blooms best in full
sun and moist, organically rich, well drained soils. It flowers best if not planted on the south side of buildings
as that would warm up early and cause the flowers to bloom early and possibly be subject to frost damage.
Potential diseases include leaf spots, anthracnose, canker, dieback and powdery mildew. Insect problems
include weevils, scale, thrips and snails.
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Phenology
PLANT
Phlox subulata ‘Snowflake’
Pieris floribunda
Podophyllum peltatum (mayapple)
Trillium pusillum
Viburnum prunifolium (black haw
viburnum)
PLANT STAGE (Bud with color,
First bloom, Full bloom, First
leaf)
Full bloom
Full bloom
Full leaf and Bud
Full bloom
Full bloom
LOCATION
Ellicott City (April 21)
Silver Run (April 16)
Ellicott City (April 21)
Silver Run (April 16)
Columbia (April 18)
Degree Days (As of April 20)
Annapolis Naval Academy (KNAK)
211
Baltimore, MD (KBWI) College Park (KCGS)
239
Dulles Airport (KIAD) Ellicott City (E247)
206
Fairfax, VA (D4092)
Frederick (KFDK)
139
Greater Cumberland Reg (KCBE) Gaithersburg (KGAI)
196
Martinsburg, WV (C1672)
Natl Arboretum.Reagan Natl (KDCA)
324
Rockville (C2057)
Salisbury/Ocean City (KSBY)
254
St. Mary’s City (St. Inigoes, MD-KNUI)
Westminster (KDMW)
204
Important Note: We are now using the Online Phenology and Degree-Day Models site.
221
215
275
188
167
167
285
Use the following information to calculate GDD for your site: Select your location from the map
Model Category: All models
Select Degree-day calculator
Thresholds in: Fahrenheit F
Lower: 50
Upper: 95
Calculation type: simple average/growing dds
Start: Jan 1
US DOT Forum
June 8, 2016: 8:00 a.m. to noon
Location: 6772 Rockawalkin RD, Hebron, MD
MSP Senior Trooper Lambert and Master Trooper Dean will provide an update on changes to the Federal Motor
Carrier Regulations and Maryland Transportation Article. This Forum will provide both education and one on
one question and answer time. It covers recent changes to FMCSR and the Maryland Transportation Article.
Including: Medical certificates; Load securement; Breakaway device; Hub covers; Seatbelt use; Speeding and;
no handheld cell phones.
8:00 – 10:00 Presentations on Carrier/Companies responsibilities topics such as: Insurance; Maintaining accident
records; Driver qualification files; Drug and alcohol testing and; Maintaining log books and time records. Requirements
for training, transporting and incident reporting for HAZMAT materials will be discussed if applicable to the attendees.
10:00 – 11:00 ST Lambert and MT Dean will demonstrate the concepts during a mock inspection of two vehicles. One
vehicle will be CDL, the other non-CDL.
11:00 – Noon Open Question and Answer Forum
Contact Ginny Rosenkranz, Extension Educator, Commercial Horticulture 410-749-6141 to sign up for
this free US DOT Forum
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Commercial Horticulture Conferences
Pesticide Recertification Conference (Eastern Shore)
June 3, 2016
Brochure will be posted soon
Pesticide Recertification Conference
June 10, 2016
Location: Montgomery County Extension Office, Derwood, MD
Brochure is posted online
Maryland Christmas Tree Association Summer Meeting
Saturday June 25, 2016 at Thomas Tree Farm, 3501 Hanover Pike, Manchester, MD
For info: wayne@thomastreefarm.com
CONTRIBUTORS:
Stanton Gill
Extension Specialist
sgill@umd.edu
410-868-9400 (cell)
David Clement
Plant Pathologist
clement@umd.edu
Paula Shrewsbury
Extension Specialist
pshrewsb@umd.edu
Andrew Ristvey
Extension Specialist
aristvey@umd.edu
Karen Rane
Plant Pathologist
rane@umd.edu
Ginny Rosenkranz
Extension Educator
rosnkrnz@umd.edu
Chuck Schuster
Extension Educator
cfs@umd.edu
Nancy Harding
Faculty Research
Assistant
Thank you to the Maryland Arborist Association, the Landscape Contractors Association of MD, D.C. and VA, the
Maryland Nursery and Landscape Association, Professional Grounds Management Society, and FALCAN for your
financial support in making these weekly reports possible.
Photos are by Suzanne Klick or Stanton Gill unless stated otherwise.
The information given herein is supplied with the understanding that no discrimination is intended and no
endorsement by University of Maryland Extension is implied.
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.