National Snapshot

Quarantine maps redrawn coast to coast

A week of regulatory movement on three fronts: Texas confirmed EAB in five more counties (Hardin County now marks the pest's southernmost U.S. boundary), citrus greening reached Imperial County, California for the first time, and APHIS federally expanded Ohio's box tree moth quarantine by seven counties. In the field, magnolia scale crawlers are at peak emergence, orangestriped oakworm is defoliating at full strength, bagworm bags are closing (spray season over — handpick from here), and SLF egg-laying is only weeks away.

Borer

EAB expands in Texas — Delta, Erath, Hardin, Walker, and Wood counties confirmed via purple-trap monitoring, eight new counties this year. Flight season is over nationally, but larvae tunnel on; keep ash wood local and inject high-value trees on cycle.

Sap feeder

Scale crawlers at peak — magnolia scale crawlers are fully out, with white prunicola scale second-generation crawlers on cherry laurel and Prunus close behind. Tape-trap and treat at first crawler; the window narrows by Labor Day.

Caterpillar

Orangestriped oakworm is at peak defoliation (see the featured pest), with yellownecked, walnut, and azalea caterpillars active and fall webworm nests at maximum size. Bagworm bags are closing — handpick only now.

Invasive

Spotted lanternfly adults remain heavy on woody trees; egg-mass season opens next month. Finish flagging tree-of-heaven and smooth-barked hosts on your routes this week.

Disease

Citrus greening (HLB) hits Imperial Co., CA — first county detection, 5-mile quarantine to the border. Elsewhere, bacterial leaf scorch and tar spot are at peak visibility; confirm scorch by lab before treating.

Mite

Spider mites remain active on dusty, stressed canopies but pressure begins easing as nights cool; rescue treatments rarely pay this late — protect predators.

Methodology Note

How we report growing degree days

Growing degree days accumulate from January 1 and only climb through the season. Each region's reading is anchored to the latest measured cooperative-extension station data (base 50°F), so figures track real, on-the-ground heat rather than the calendar. Because published station data can lag by a week or two, always confirm against your nearest local station (NEWA, Enviroweather, or your state tool) before timing an application.

Pest on the Chart · This Week

Orangestriped Oakworm

Anisota senatoria

This week's pest on the chart, and the source of most late-August "my oak is dying" calls. The yellow-striped, black caterpillars with their telltale curled-horn pair feed gregariously, stripping pin and willow oaks branch by branch and raining frass on driveways, decks, and cars underneath — often the first thing clients notice. Defoliation looks alarming but comes so late in the season that established trees have already banked most of the year's photosynthesis; the damage is largely cosmetic on healthy oaks. Young, newly planted, or already-stressed trees are the exception worth protecting.

Stage Now

Larvae feeding

Top Hosts

Pin·Willow oak

Rx Note

Mostly cosmetic

℞ — Lead with client education: late-season defoliation on an established oak is tolerable, and the caterpillars finish within weeks. Where action is warranted — young or stressed trees, or intolerable frass zones — handpick or prune out the gregarious clusters while larvae are concentrated, or treat young larvae with Btk or spinosad; larger larvae need chlorantraniliprole. Skip broad-spectrum sprays on big oaks: they cost more than the feeding does and take out the natural enemies that usually collapse outbreaks within a season or two.

Regional Alert

New Detections & Quarantine Moves

Three verified regulatory developments this week, on three different fronts of the country.

Texas

EAB confirmed in five new counties — Texas A&M Forest Service's purple-trap program confirmed emerald ash borer in Delta, Erath, Hardin, Walker, and Wood counties (Aug 20) — eight new counties this year, with Hardin County now the insect's southernmost U.S. boundary. Coordinate with TDA quarantine zones before moving ash material.

California

First HLB detection in Imperial County — CDFA and USDA confirmed citrus greening in a single Calexico residential tree (Aug 18), triggering a mandatory 5-mile quarantine whose southern edge is the U.S.–Mexico border. The tree has been removed; psyllid surveys and treatments are underway within 250 m. No citrus material in or out of the zone.

Ohio

APHIS expands federal box tree moth quarantine — Federal Order DA-2026-23 (Aug 4) adds Ashtabula, Clark, Cuyahoga, Lake, Lorain, Lucas, and Preble counties, mirroring ODA's January expansion. Interstate boxwood movement from quarantined areas requires a compliance agreement and state-issued certificate.

℞ Check the map before the truck rolls. All three moves change what can legally cross a county line — verify current zone boundaries, carry compliance paperwork where required, keep host wood and plant material local, and report suspect finds to the state program.

Regional Rx · 5 Zones

Read your zone like a chart

Each card reports the region's growing-degree-day reading (the vital sign that drives every timing call), what's active now (Diagnose), and how to time treatment (℞). GDD ranges are typical for the week, base 50°F from Jan 1 — always confirm against your nearest station.

NE

Northeast & New England

ME · NH · VT · MA · RI · CT · NY

GDD · Accumulated

~1,900–2,300

0

1,500

3,000+

Conditions: Accumulation advancing from the July UMass base (base 50°F); UMass's late-August issue lands this week. Drought stress persists with scorch widespread; laurel wilt (Suffolk Co.) and oak wilt (Finger Lakes) districts stand.

Diagnose · Active Now

•

Magnolia scale crawlers at peak emergence — treat now; cottony camellia & lecanium behind them.

•

Orangestriped oakworm and late-summer caterpillars defoliating; fall webworm nests at maximum size.

•

Bagworm bags closing on arborvitae and juniper — spray window over.

•

Spotted lanternfly adults heavy; egg-laying begins next month.

•

Laurel wilt — keep scouting Long Island sassafras and spicebush; drought & bacterial leaf scorch browning crowns.

℞

Prescribe · Timing & Materials

•

Scale crawlers: horticultural oil (repeat per label) or IGR (pyriproxyfen / buprofezin) at first crawler — this is the week.

•

Bagworm: handpick and destroy bags from now through spring; book the June Btk program for infested plants.

•

Oakworm / webworm: educate on late-season tolerance; prune clusters and nests; Btk / spinosad on young larvae only where warranted.

•

Laurel wilt / oak wilt: don't move host wood or firewood; oak pruning stays on hold into September.

MA

Mid-Atlantic & DMV

NY · NJ · PA · MD · DE · DC · VA · WV

GDD · Accumulated

~2,550–3,150

0

1,500

3,000+

Conditions: Warm and humid. SLF adults remain at their late-summer peak with central Maryland the state's most infested zone. Box tree moth pressure keeps building regionally — MD's four-county district stands and New Jersey's Cape May Co. quarantine is in force.

Diagnose · Active Now

•

White prunicola scale 2nd-generation crawlers on cherry laurel and Prunus; magnolia scale crawlers at peak.

•

Orangestriped oakworm & yellownecked caterpillars defoliating oaks; fall webworm nests large.

•

Spotted lanternfly adults heavy on trap trees; egg-mass season opens next month.

•

Box tree moth — monitor boxwood in and beyond the MD and NJ quarantine zones.

•

Bacterial leaf scorch at peak expression on oaks, elms, and sycamore; bagworm bags closing.

℞

Prescribe · Timing & Materials

•

Scale crawlers: horticultural oil + IGR at first crawler on Prunus and magnolia — tape-trap to confirm.

•

Spotted lanternfly: keep trap trees treated; finalize September egg-mass scouting routes; report new counties.

•

Box tree moth: Btk / spinosad on active larvae; report finds; move boxwood only under compliance in quarantine zones.

•

Oakworm: educate on tolerance; handpick clusters; treat only young or stressed oaks.

•

Bacterial leaf scorch: confirm by lab; support vigor; consider oxytetracycline injection for high-value trees.

SE

Southeast

NC · SC · GA · TN · AL · MS · FL · VA

GDD · Accumulated

~3,300–4,300

0

1,500

3,000+

Conditions: Hot and humid with late-summer caterpillars at full strength. Watch for fall armyworm flare-ups in turf after tropical rain events. Laurel wilt keeps advancing; keep laurel-family hosts on the scouting list.

Diagnose · Active Now

•

Orangestriped oakworm at peak on pin and willow oaks; greenstriped mapleworm, yellownecked & azalea caterpillars active.

•

Fall armyworm watch in turf and young plantings following storm systems.

•

Crapemyrtle bark scale + aphid sooty mold; fall webworm second-generation nests large.

•

Laurel wilt advancing — scout redbay, sassafras, and bay; southern pine beetle on stressed pines.

•

Cercospora leaf spot & powdery mildew on crape myrtle; southern red spider mite active.

℞

Prescribe · Timing & Materials

•

Caterpillars: tolerate on large trees; handpick oakworm clusters; Btk on young larvae where warranted.

•

Fall armyworm: scout at dawn/dusk after storms; treat actively feeding larvae fast with Btk / spinosad / chlorantraniliprole — they outgrow control quickly.

•

Crapemyrtle bark scale: IGR at crawlers, dormant hort oil later; wash sooty mold; conserve lady beetles.

•

Laurel wilt / borers: don't move host wood or firewood; reduce stress; report suspects.

•

Crape myrtle disease: resistant cultivars, airflow, labeled myclobutanil / propiconazole.

MW

Midwest & Great Lakes

OH · MI · IN · IL · WI · MN · IA · MO

GDD · Accumulated

~2,350–2,950

0

1,500

3,000+

Conditions: Running ~2 weeks ahead. New this week: APHIS federally expanded Ohio's box tree moth quarantine to include Ashtabula, Clark, Cuyahoga, Lake, Lorain, Lucas, and Preble counties. Magnolia scale crawlers are at peak; oak pruning stays on hold.

Diagnose · Active Now

•

Box tree moth — Ohio's federal quarantine now spans additional counties; monitor boxwood across the region.

•

Magnolia scale crawlers at peak emergence — the window is open now.

•

Walnut & yellownecked caterpillars defoliating; fall webworm nests large; bagworm bags closing.

•

Emerald ash borer larvae tunneling; elm zigzag sawfly on elms.

•

Oak wilt risk continues — hold oak pruning a few more weeks.

℞

Prescribe · Timing & Materials

•

Box tree moth: Btk / spinosad on active larvae; report finds; boxwood moves interstate only under compliance agreements.

•

Magnolia scale: horticultural oil (repeat per label) or IGR at first crawler; hose honeydew.

•

Bagworm: handpick through spring; book June Btk for next season.

•

EAB: systemic trunk injection (emamectin benzoate) for high-value ash on cycle; keep ash wood local.

•

Oak wilt: paint unavoidable wounds; don't move oak wood.

W

West & Pacific

CA · OR · WA · NV · AZ · CO · UT · ID · MT

GDD · Accumulated

Highly variable

Coast / high elev.

—

Inland / low desert

Conditions: New this week: citrus greening (HLB) confirmed for the first time in Imperial County, CA — a single Calexico tree, now removed, with a 5-mile quarantine running to the U.S.–Mexico border. Fire season and irrigation stress continue to drive the borer picture.

Diagnose · Active Now

•

Huanglongbing / citrus greening — first Imperial Co. detection; Asian citrus psyllid surveys underway within 250 m of the find.

•

Wood-boring beetles on stressed trees — invasive shothole borers, goldspotted oak borer, Mediterranean oak borer.

•

Emerald ash borer in Oregon — five Willamette Valley counties remain under quarantine.

•

Spider mites on dusty canopies; aphids with honeydew; yellowjackets at their worst.

℞

Prescribe · Timing & Materials

•

HLB zone: keep citrus plant material local — nothing in or out of the quarantine or across borders; cooperate with trapping crews; recommend removal of uncared-for backyard citrus.

•

Borers: deep-water summer-rainfall-adapted trees, avoid fresh wounds, don't move ash material or firewood; protect high-value ash in EAB zones and report.

•

Spider mites: rinse dust; selective miticide only if damaging; protect predators.

•

Stone-fruit canker/blight: prune out in dry weather, cutting into healthy wood.

•

Fire: maintain defensible space and thin fuel ladders.

Field notes — read before you spray

This is crawler week. Magnolia and white prunicola scale crawlers are at peak — tape-trap, treat at first crawler, repeat per label. By Labor Day the window is closing.

Sell tolerance where it's the right call. Late-season oakworm defoliation on established oaks rarely justifies a spray — the education is worth more than the application.

Quarantines moved this week. Texas (EAB), Imperial Co. CA (HLB), and Ohio (box tree moth) all redrew their maps — verify zones before moving wood or plant material.

Sources · Cooperative Extension & USDA

Compiled from public reporting by cooperative extension and state/federal partners, including Texas A&M Forest Service (EAB detections, Aug 2026); CDFA & USDA (Imperial Co. HLB quarantine); USDA APHIS Federal Order DA-2026-23 & Ohio Dept. of Agriculture (box tree moth); NY DEC & Ag and Markets (laurel wilt and oak wilt districts); NJDA (Cape May Co. BTM); UMass Extension; University of Maryland Extension & MDA; Virginia Cooperative Extension & VDACS; NC State & Clemson; Michigan State, Iowa State & UMN; UC Statewide IPM Program; Oregon Dept. of Agriculture / ODF; and USDA NIFA / Forest Service. Regional summaries are paraphrased; consult the original bulletins and your local extension office for specifics.

EAB claims five new Texas counties, HLB reaches Imperial County, and scale crawlers hit peak — your region-by-region windows for Aug 17–24.

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