8.2 Turf, Ornamental, Greenhouse & Right-of-Way Pest Control

8.2 Turf, Ornamental, Greenhouse & Right-of-Way Pest Control

Quick Answer: The ornamental and turf, greenhouse, and right-of-way pest control classes (NDAC 60-03-01-05(4), (17), and (7)) govern managed landscapes, shelterbelts, greenhouse operations, and transit corridors. In managed turf, pre-emergence crabgrass herbicides must be timed to 50°–55°F soil temperatures at a 2-inch depth for 3 consecutive days (coinciding with forsythia bloom), whereas perennial broadleaf weeds are controlled most effectively in the fall during downward carbohydrate translocation. Late-fall fungicides prevent devastating snow molds (Typhula and Microdochium). For Emerald Ash Borer (EAB), systemic emamectin benzoate trunk micro-injection provides multi-year protection. In greenhouses, enclosed-space WPS ventilation rules and biological control agents (Encarsia formosa, Phytoseiulus persimilis) require careful coordination. In right-of-way corridors, cut-stump treatments must be applied within 15 minutes, and leafy spurge requires combined Aphthona flea beetle biocontrol and selective herbicides.

Ornamental and Turf Pest Control: Turfgrass Pest & Weed Management

Commercial turf managers oversee golf courses, athletic complexes, sod farms, commercial campus landscapes, and residential properties across North Dakota. Maintaining turf vigor while preventing chemical runoff and non-target pesticide injury requires precise timing linked to soil temperatures and weed phenology.

Pre-Emergence Crabgrass Management

Crabgrass (Digitaria ischaemum - smooth crabgrass, and D. sanguinalis - large crabgrass) is a prolific summer annual grass. Seeds germinate in the top quarter-inch of soil when conditions become favorable:

• Soil Temperature Benchmark: Pre-emergence herbicides (dithiopyr, prodiamine, pendimethalin) must be applied and watered into the soil before soil temperatures reach 50°–55°F at a 2-inch depth for 3 consecutive days.
• Phenological Indicator: Full yellow bloom of Forsythia shrubs reliably signals that spring soil temperatures are approaching the critical 50°F threshold. Common lilac (Syringa vulgaris) first leaf emergence serves as a secondary indicator.
• Barrier Integrity: Pre-emergent chemistries establish a chemical barrier in the surface soil that terminates emerging grass radicles. Applicators must advise clients never to aerate, verticut, or aggressively rake turf following application, as mechanical disruption ruptures the chemical barrier and triggers crabgrass emergence.

Perennial Broadleaf Weed Management: Fall vs. Spring Dynamics

Perennial broadleaf weeds—including dandelion (Taraxacum officinale), ground ivy / creeping Charlie (Glechoma hederacea), white clover (Trifolium repens), and broadleaf plantain (Plantago major)—are widespread across North Dakota turf.

SPRING APPLICATION (Suboptimal):
Photosynthetic sap flow is directed UPWARD from roots to expand new leaves.
  └── Foliar herbicides burn off top growth, but roots survive → Vigorous re-sprouting.

FALL APPLICATION (Optimal: Late September to Mid-October):
Following light frosts, weeds direct sap flow DOWNWARD to crowns/roots for winter storage.
  └── Systemic auxins (2,4-D, dicamba, triclopyr) translocate deep into roots → Complete kill.

Applying systemic broadleaf herbicides (three-way formulations combining 2,4-D, dicamba, and mecoprop/MCPP, or triclopyr) in late autumn after the first light frosts achieves complete root mortality while eliminating spring non-target drift risks to neighboring ornamental gardens and vegetable plantings.

Harsh Northern Plains Turf Pathology: Snow Molds & Foliar Blights

North Dakota's extended sub-zero winters, prolonged snow cover, and humid summers create severe microclimates for specialized turf pathogens:

Ornamental & Shelterbelt Pest Management: Emerald Ash Borer (Agrilus planipennis)

Shelterbelts, farmstead windbreaks, and municipal urban canopies in North Dakota are predominantly composed of Green Ash (Fraxinus pennsylvanica) and Black Ash (Fraxinus nigra), representing over 60% to 80% of all deciduous trees across the state. The invasive Emerald Ash Borer (EAB), a wood-boring buprestid beetle, presents an existential threat to these trees.

• Diagnostic Signs: Adult beetles chew distinct D-shaped exit holes (1/8-inch wide) through bark. Larvae feed in the phloem, cambium, and outer xylem, cutting dense, S-shaped serpentine galleries packed with frass. Crown dieback, vertical bark fissures, heavy woodpecker flecking, and epicormic water sprouting on the lower trunk indicate advanced infestation.
• Preventive Systemic Trunk Micro-Injection: The gold-standard treatment is trunk micro-injection of emamectin benzoate. Applied into the basal root flare xylem during active spring sap flow, emamectin benzoate translocates throughout the canopy, providing 2 to 3 years of 99% larval and adult mortality.
• Basal Soil Drench: Soil applications of systemic imidacloprid provide 1 year of suppression but require root uptake through moist soil and are strictly restricted near open water or sandy aquifers.
• Regulatory Quarantine: Applicators and tree care services must strictly comply with North Dakota Department of Agriculture quarantines prohibiting the movement of untreated ash firewood, ash logs, nursery stock, and wood chips out of designated quarantined areas.

Greenhouse Class: Pest Control Dynamics & Safety

Greenhouse environments create unique agronomic and toxicological conditions. Elevated temperatures, high relative humidity, year-round host plant availability, and the complete absence of natural rainfall allow pest populations to reproduce rapidly with overlapping generations:

• Worker Protection Standard (WPS) Enclosed-Space Mandates: Applicators must post bilingual warning signs at all greenhouse entrances prior to application. During aerosol, fog, mist, or smoke applications, the entire greenhouse remains under strict quarantine. Re-entry is prohibited until mandatory ventilation criteria are met: (1) 10 complete air exchanges via mechanical ventilation, (2) 2 hours of continuous mechanical ventilation, or (3) 4 hours of passive natural ventilation.
• Personal Protective Equipment (PPE): Pesticide aerosols remain suspended in greenhouse air currents for extended periods. Applicators must wear NIOSH-approved half-mask or full-face respirators equipped with Organic Vapor (OV) cartridges and P100 particulate pre-filters.
• Biological Control Agents (BCAs): Modern greenhouse IPM prioritizes the release of beneficial organisms. Applicators must understand chemical compatibility:
  • Encarsia formosa: A tiny parasitic wasp that attacks greenhouse whiteflies (Trialeurodes vaporariorum). The female oviposits inside whitefly nymphs; parasitized scales turn distinctively black.
  • Phytoseiulus persimilis: A voracious predatory mite that feeds exclusively on all life stages of the two-spotted spider mite (Tetranychus urticae).
  • Chemical Disruption Warning: Broad-spectrum residual insecticides (pyrethroids, organophosphates) eradicate BCAs. Only selective, low-residual chemistries (insecticidal soaps, horticultural oils, targeted IGRs) may be integrated.

Right-of-Way Pest Control

Right-of-Way applicators manage vegetation along state and township highways, county roadsides, railroad ballasts, electrical transmission easements, petroleum pipelines, and drainage ditch banks. The operational goal is maintaining sight lines, preventing snow drifting, eliminating fire hazards, protecting utility infrastructure, and eradicating state-listed noxious weeds.

Primary Right-of-Way Noxious Weeds in North Dakota

• Leafy Spurge (Euphorbia esula): An aggressive creeping perennial with a massive root system reaching depths of 15 to 30 feet and abundant root buds. The plant contains a toxic, milky latex sap that causes blistering, eye irritation, and digestive inflammation in cattle.
  • Biological Control: Coordinated release of Aphthona flea beetles (Aphthona lacertosa, Aphthona nigriscutis). Larvae feed internally on root hairs and root crowns, while adult beetles defoliate foliage during mid-summer. Highly successful in open, sunny prairie sites.
  • Chemical Control: Selective systemic herbicides including picloram (Tordon; highly persistent in soil, prohibited on sandy soils or near shallow groundwater), aminopyralid, and quinclorac applied in late spring or fall.
• Spotted Knapweed (Centaurea stoebe): Biennial/perennial that invades disturbed gravel roadsides and railroad ballasts. Secretes allelopathic root compounds that inhibit native grass competition. Managed with aminopyralid or clopyralid.
• Absinth Wormwood (Artemisia absinthium): Aromatic perennial shrub infesting roadsides and pasture approaches; taints dairy milk and livestock forage. Readily controlled with fall applications of 2,4-D or dicamba.
• Saltcedar (Tamarix ramosissima): Invasive woody phreatophyte colonizing riparian ditch banks and western waterways, consuming immense water volumes and exuding surface salts.

Specialized Right-of-Way Application Techniques

• Basal Bark Treatment: Formulations of oil-soluble ester herbicides (e.g., triclopyr ester) blended with penetrating horticultural oil or diesel fuel. The mixture is sprayed onto the lower 12 to 18 inches of woody brush trunks completely encircling the stem down to the groundline until thoroughly wet without runoff. Effective on stems under 6 inches in diameter during any season except when snow covers the trunk base.
• Cut-Stump Treatment: Application of concentrated water-soluble amine or oil-soluble ester herbicide directly to the exposed vascular cambium ring of freshly severed stumps immediately within 15 minutes of cutting. Delaying application allows xylem and phloem vessels to dry and seal with resin, preventing chemical translocation and leading to vigorous root re-sprouting.
• Foliar Drift Mitigation: Roadside boom sprayers operate directly adjacent to sensitive farmstead shelterbelts and broadleaf cropland (soybeans, sunflowers). Applicators must utilize low-drift air-induction nozzles, operate at pressures below 30 psi, maintain travel speeds under 10 mph, and maintain mandatory downwind buffer zones.

Independent Preparation Notice

This study guide is an independent educational publication developed by OpenExamPrep. It is not affiliated with, sponsored by, endorsed by, or produced in partnership with the North Dakota Department of Agriculture, North Dakota State University Extension, or the EPA.