RHFB — Plant & Pest Advisory

May 12, 2025 Tim Waller

Ornamental IPM – Blight and pest alerts – next IPM Session 5/13/25

Serious potential for Boxwood Blight
Bronze Birch Borer (BBB) approaching adult emergence
Clearwing Borer adult flight – time to monitor
Red-headed flea beetle (RHFB) egg hatch – adult emergence soon
Oomycete material considerations
(click the ‘Read More’ below for complete dates in S-C-Northern NJ per pest)

Still time to Sign up for the 2025 – Rutgers Ornamental IPM Program

(Join us for the next Session Tuesday 5/13/25)

Note we have Clearwing borer lures and wing or delta traps, scale crawler tape, and yellow sticky cards available to commercial grower program members at our Cumberland (twaller@njaes.rutgers.edu) and Monmouth (william.errickson@njaes.rutgers.edu) RCE offices.

Click here for a PDF of April 22, 2025 webinar (contains information on RHFB and early Clearwing borer treatments) Click here for VIDEO of April 22, 2025 webinar
Click here for a PDF of April 08, 2025 webinar (Contains information on aphids and boxwood leafminer) Click here for VIDEO of April 08, 2025 webinar

June 14, 2023 Tim Waller, William Errickson and Steven K. Rettke

Nursery Pest and Disease Update 6/15/2023

In this edition:

Insects:
- MORE Scale crawlers emerging
- Borers
- Beetles
Diseases:
- Oomycete root diseases (Phytophthora, Pythium, Phytopythium)
- Leaf spots / foliage diseases
- Boxwood Blight – reminder
- Virus observations
Nutrient Management
- Managing Soluble Salts by monitoring EC
- Plant Tissue analysis
Plant Spotlight:
- American Holly (Ilex opaca)
Cumberland Nursery / NJNLA – Twilight: tonight (6/15) for NURSERYMEN ONLY (contact twaller@njaes.rutgers.edu or 856-451-2800 Ext. 1. for details)

Please click “read more” below to get updates on pests, diseases, and other important resources for the week of 6/15/2023.

May 14, 2023 Tim Waller, William Errickson and Steven K. Rettke

Nursery Pest and Disease Update 5/15/2023

In this edition:

Insects:
- Scale crawler emergence
- Borer insects
- Upcoming problem pests / Redheaded flea beetle / SLF / Pest Scouting Guides
Diseases:
- Leaf spot / foliage disease management
- Fire blight on Rosaceous hosts
- Canker fungi
- Boxwood blight
- Oomycete root diseases (Phytophthora, Pythium, Phytopythium)
Plant Spotlight:
- NJ native azalea species

Please click “read more” below to get updates on pests, diseases, and other important resources for the week of 5/15/2023.

April 27, 2023 Tim Waller

Nursery Pest Update 4/25 – 5/5/2023

Please note: The Rutgers Nursery and Green Industry Working Group is working to deliver regular pest and disease updates throughout the season. These will be in addition to important alerts, critical topics, and pesticide credit opportunities. This tool is made for you, the commercial agriculture business, so please let us know if there are particular topics you would like to see included in the regular update.

Email: twaller@njaes.rutgers.edu Phone: 856-451-2800 Ext. 1.

Insect Pests

Projected GDD50 accumulation as of 4/25/2023 (these change throughout the season!)
Region	Location	25-Apr	1-May	1-Jun	1-Jul	1-Aug
Southern	Upper Deerfield (NJ50)	251	281	682	1370	2218
Central	Howell / Freehold (NJ10)	188	207	537	1160	1957
Northern	High Point (NJ59)	142	143	371	864	1507
Forecast: 7-month NMME based seasonal climate forecast (USPEST.ORG)

Please download and print the Rutgers Nursery and Landscape Pest Scouting Guide or Conifer and Christmas Tree Pest Scouting Guide and refer to this post “Obtaining your local growing degree-days (GDD)” for additional information. (See pest scouting guides for complete list of references)

Please SHARE what you SEE!! If you see a pest, disease, otherwise interesting or troublesome issue please report it to the Working Group by following the QR Code on the front of the Pest Scouting Guides or by filling out this reporting form.

Please continue reading for much more detailed and important information!

May 24, 2022 Tim Waller

Nursery Pests Scouting June – Bagworms, Scales, Borers, RHFB, BWB

Red-headed flea beetle – Adult emergence beginning any day now

Please refer to this timeline of pest development compiled by Tim Waller in communication with Brain Kunkel (Unv. Del) and Danny Lauderdale (NC State)

Contains material selection and timing, along with regime information and considerations

Boxwood Blight Alert – Infection Potential (Saturday) 5/27

Boxwood Blight Risk Assessment as of 5/24/2022
Region	Location	CODE	24-May	25-May	26-May	27-May	28-May	29-May
Southern	Upper Deerfield	NJ50	Very Low	Very Low	Low	High Risk	Very Low	Very Low
Central	Howell / Freehold	NJ10	Very Low	Very Low	Low	Infection Risk	Very Low	Very Low
Northern	High Point	NJ59	Very Low	Very Low	Very Low	Infection Risk	Very Low	Low
Check local boxwood blight risk here (CLICK HERE – input your area code – select closest weather station – check 7-14 prediction – click on graph / table)

Refer to the most recent Alert for more information – CLICK HERE

Pest Scouting – Please refer to these documents for a full listing of insects pests for your area corresponding to growing degree-days (GDDs).

Nursery and Landscape Pest Scouting Guide 2022 PDF (note this contains conifer pests as well)
Conifer Pest Scouting Guide 2022 PDF

Contact if seeing insects at different times: twaller@njaes.rutgers.edu (or call the Cumberland County Extension Office – 856-451-2800)

The following key groups of pests will be active, vulnerable, or otherwise treatable during the next month throughout most of NJ. Here, bagworms, scale insects and borers with key life stage events during the 350-1500 GDD timeframe are discussed. Note there are many other insect pests present this time of year so please view the pest scouting guides above for your particular needs.

Projected GDD50 accumulation as of 5/24/2022 (USPEST)						Note: Growing degree-day values utilize daily average air temperatures with a minimum temperature threshold (a.k.a. ‘base’) of 50F = GDD50 (max. temp. threshold set at 95F). These values are accumulated from a biofix date, such as January or March 1st in the NE USA. Provided GDD50 are scouting ranges and should be truthed.
Region	Location	Station	24-May	1-Jun	1-Jul
South	Upper Deerfield	NJ50	488	638	1358
Central	Howell / Freehold	NJ10	426	551	1203
North	High Point	NJ59	288	387	909
Forecast: NOAA NCEP Coupled Forecast System model version 2 (CFSv2) forecast system (3.5 months) (USPEST.ORG)

Refer to this post “Obtaining your local growing degree-days” for additional information

BAGWORMS (600-900 GDD) (Bagworm hatch prediction as of 5/24/22 – now until July 14 (Southern NJ (NJ50)))

Crop type

Common Name

Scientific Name

GDD Min (50F)

GDD Max (95F)

Reference

Developmental / Target Stage

Conifer mostly, many minor hosts

Bagworm

Thyridopteryx ephemeraeformis

600

900

Larvae (early instars) –

ONLY CONTROL WINDOW

Refer to this post for additional information on Bagworms

BORER Insect Activity for 350 – 1500 GDD (Now until ~July 1 in Southern NJ (NJ50))
Crop type	Common Name	Scientific Name	GDD Min (50F)	GDD Max (95F)	Reference	Developmental / Target Stage
Malus, Prunus, many	Lesser peach tree borer	Synanthedon pictipes	350	375	4	Adult flight, egg laying
Dogwood, apple, pecan, elm, hickory, willow	Dogwood borer	Synanthedon scitula	350	850	4	adults, eggs, caterpillars
Birch	Bronze Birch Borer	Agrilus anxius	440	880	RU	Adults (egg laying)
Malus, Prunus, many	Peach Tree Borer	Synanthedon sp.	500	600	RU	Adults – emerge (1st treatment both types)
Rhododendron	Rhododendron borer	Synanthedon rhododendri	509	696	RU	Adults emerge
Malus, Prunus, many	Greater peach tree borer	Synanthedon exitiosa	575	710	4	Adult emergence
Many	Roundheaded appletree borer	Saperda candida	802	1129	RU	Adults
Ash	Emerald ash borer	Agrilus planipennis	1000	1200	4	Peak adult activity
Malus, Prunus, many	Peachtree borer	Synanthedon sp.	1500	1800	RU	Larvae Treatment
Many	Roundheaded apple tree borer	Saperda candida	1514	1798	5	Typical treatment window
Conifer	Nantucket tip moth	Rhyacionia frustrana	1514	1917	RU	Adults 2nd generation

Click here – “Identifying Clearwing Moth Borers in Pheromone Traps” or “Differentiating the Common Wood Borers of Ash Trees”

August 4, 2021 Tim Waller

Nursery – Pest Scouting Guide for August – Reminders – Need a few more nurseries for Phytophthora sampling

NURSERY PEST SCOUTING GUIDE – August (1300-2200 GDD₅₀)

Please download and print the pest scouting guide resource (printable version of the information below for your desk or truck) –(click on the link and then print):

Pest Scouting Guide August 2021 (1600-300 GDD₅₀)
To determine your local growing degree-days, please review this post “Obtaining your local growing degree-day information”

Projected GDD50 accumulation as of 8/4/2021
Region	Location	1-Aug	1-Sep	1-Oct	1-Nov	–
Southern	Upper Deerfield (NJ50)	2145	2931	3477	3682	–
Central	Howell / Freehold (NJ10)	1896	2630	3109	3249	–
Northern	High Point (NJ59)	1490	2045	2352	2384	–
Forecast: NOAA NCEP Coupled Forecast System model version 2 (CFSv2) forecast system (3.5 months) (USPEST.ORG)

(Same material as downloads)

Pest Scouting – Growing Degree-day Ranges						(1600-3000 GDD50)
CROP TYPE	Common Name	Scientific Name	GDD Min (50F)	GDD Max (95F)	Reference	Developmental / Target Stage
Many	Redheaded flea beetle	Systena frontalis	1570	1860	Udel.	2nd generation egg hatch
Many	Two-banded Japanese weevil	Pseudocneorhinus bifasciatus	1644	2271	RU	Adults
Willow	Willow twig aphids	Lachnus spp.	1644	2271	5	Typical treatment window
Conifer	Juniper webworm	Dichomeris marginella	1645	1917	RU	Larvae Treatment
Euonymus	Euonymus Scale	Unaspis euonymil	1700	–	RU	Prophylactic 2nd generation treatments
Conifer	Cryptomeria scale	Aspidiotus cryptomeriae	1750	2130	RU, 4	Crawlers emerge (2nd generation)
Many	Obscure scale	Melanaspis obscura	1774	–	6	Egg hatch / crawler
Oaks	Oak skeletonizer	Bucculatrix ainsliella	1798	2155	RU	Larvae
Conifer	Arborvitae leafminer	Argyresthia thuiella	1800	2200	RU	Larvae Treatment (3rd generation)
Mimosa, Honeylocust	Mimosa webworm	Homadaula anisocentra	1800	2100	RU	Larvae (2nd generation)
Conifer	Cooley spruce gall adelgid	Adelges cooleyi	1850	1950	RU	Galls open (Spruce)
Many	Redheaded flea beetle	Systena frontalis	1878	2318	Udel.	2nd generation Adults feeding
Turf	Hairy chinch bug	Blissus leucopterus	1903	2160	RU	Second generation- 50%- 2nd instars
Tulip	Tuliptree aphid	Illinoia liriodendri	1917	2033	RU	Nymphs
Conifer	Zimmerman pine moth	Dioryctria zimmermani	1917	2154	5	Treatment window (adult flight-1700 GDD)
Mainly Oaks	Orangestriped oakworm	Anisota senatoria	1917	–	6	Egg hatch – early instars
Conifer	White pine aphid	Cinara strobi	1991	2271	RU	Adults
Rhododendron	Azalea whitefly	Pealius azaleae	2032	2150	5	Adults/nymphs (3rd generation)
Maple	Sugar maple borer	Glycobius speciosus	2032	2375	5	Typical treatment window
Conifer	Maskell scale	lepidosaphes pallia	2035	–	6	Egg hatch / crawler (2nd generation)
Mainly Tulip	Tulip tree scale	Toumeyella liriodendri	2037	2629	RU	Crawlers (1st generation)
Mainly Magnolia	Magnolia scale	Neolecanium cornuparvum	2155	2800	RU	Crawlers (1st generation)
Euonymus	Euonymus Scale	Unaspis euonymil	2235	–	6	Egg hatch / crawler (2nd generation)
Locust	Locust borer	Magacyllene robiniae	2271	2805	5	Typical treatment window
Poplar and Willow	Poplar and willow borer	Crytorhynchus lapathi	2271	2806	5	Typical treatment window
Conifer	Spruce spider mite	Oligonychus ununguis	2375	2806	5	Typical treatment window – fall activity
Many	Southern red mite	Oligonychus ilicis	2500	2700	5	Typical treatment window
Maple	Japanese maple scale	Lopholeucaspis japonica	2508	–	6	Egg hatch / crawler (2nd generation)
Yew, many conifers	Fletcher Scale (Yew)	Parthenolecanium fletcheri	2515	2800	RU	Fall control of overwintering stage
Conifer	Elongate hemlock scale	Fiorinia externa	2515	2625	RU	Typical treatment window – fall activity
Hardwoods	Fall webworm	Hyphantria cunea	2793	–	6	Egg hatch / crawler (2nd generation)
Conifer	Cooley spruce gall adelgid	Adelges cooleyi	2800	3000	3	Fall control of overwintering stage
Conifer	Eastern spruce gall adelgid	Adelges abietis	2800	3000	3	Fall control of overwintering stage
Note: Growing degree-day values utilize daily average air temperatures with a minimum temperature threshold (a.k.a. ‘base’) of 50F = GDD50 (max. temp. threshold set at 95F). These values are accumulated from a biofix date, such as January or March 1st in the NE USA. Provided GDD50 are scouting ranges and should be truthed.		References	RU	Rutgers Cooperative Extension – Landscape IPM Notes
			2	http://ccetompkins.org/resources/using-growing-degree-days-for-insect-management
			3	https://extension.psu.edu/ipm-basics-for-christmas-trees#section-2
			4	https://www.canr.msu.edu/ipm/agriculture/christmas_trees/gdd_of_conifer_insects
			5	https://www.agriculture.nh.gov/publications-forms/documents/landscape-pests.pdf
Daily GDD50 = (Max + Min temp.) / 2 – 50 (min temp. threshold)			6	https://extension.umd.edu/ipm/pest-predictive-calendar-landscapenursery
			7	https://www.canr.msu.edu/ipm/agriculture/christmas_trees/gdd_of_landscape_insects
			Unv. Del.	Coorespondance with Dr. Kunkel (University of Delaware)-evolving GDD ranges
Compiled 8-04-2021 – Timothy J. Waller, Ph.D. – Rutgers Cooperative Extension, Cumberland County Nursery Crops – twaller@njaes.rutgers.edu

Redheaded flea beetle considerations:

Adults should be surfacing any day in the southern regions of the state. However, in two sentinel plot locations I have yet to see second generation adults as of 8/3/2021.

Contact materials aimed at managing developing larvae (especially growth regulators) may be particularly useful at this time. Contact materials or fast acting systemics should be used to target adults in the next few days to weeks. The use of long lasting systemics should also be considered to protect foliage from the next generations adults (if a third generation occurs) and again late season to guard from first generation adults in the 2022 spring season.

These GDD estimates and corresponding calendars are evolving as we continue to learn more about this pest. If you have high populations please contact Tim Waller so we can continue to adapt our recommendations in NJ. Email: twaller@njaes.rutgers.edu

Please refer to this updated RHFB timeline printout for your desk or truck (as of 842021) (CLICK HERE)

SURVEY REQUESTS

WE NEED A FEW MORE FARMS!! Please answer a few questions if you would like to be included in a statewide Phytophthora in Conifer Nurseries sampling project

Please fill out this brief survey if you are experiencing damages due to Redheaded flea beetle (RHFB)

Contact – Timothy J. Waller – twaller@njaes.rutgers.edu for more information

Filed Under: Landscape, Nursery, & Turf, Nursery, Turf Tagged With: GDD50, Growing degree-days, IPM, Nursery, ornamental horticulture, pest scouting guide, phytophthora, red headed flea beetle, RHFB, scale insects, Scouting, survey