Top Invasive Species and How to Control Them
Invasive plants reduce biodiversity, degrade wildlife habitat, increase fire risk, and lower land value. The best results come from using the right application method at the right time with the right chemicals. Below is a field-practical control playbook for 10 of the most common invasive plants that land managers battle.
Note: Always follow the label for your use site (pasture, forestry, rights-of-way, riparian, etc.). This guide lists active ingredients only (no rates).
Chinese Tallow Tree (Triadica sebifera)
Best application methods
- Cut-stump (most reliable)
- Basal bark on smaller stems
- Foliar on seedlings
Best timing
- Late summer → early fall for foliar
- Late fall for cut-stump or basal bark
Best chemicals (active ingredients)
- Triclopyr
- Imazapyr
- Aminopyralid (site-dependent)
Pro tips
- Don’t simply cut and walk away—tallow resprouts aggressively.
- Treat cut surfaces immediately after cutting for best results.
- Plan a follow-up pass next growing season for missed seedlings.
Kudzu (Pueraria montana)
Best application methods
- Foliar treatment to full canopy
- Cut-stump for vines climbing trees or structures
Best timing
- Mid-summer → early fall during active growth
- Expect a multi-year program for long-term control
Best chemicals (active ingredients)
Pro tips
- Large leaf area = better control. Treat when vines are actively growing and fully leafed out.
- Kudzu control is a program, not a one-time event—schedule retreatment.
- Grazing or mowing can reduce biomass before spraying, but allow regrowth before foliar applications.
Cogongrass (Imperata cylindrica)
Best application methods
- Foliar broadcast or spot treatment
Best timing
- Late summer → early fall (ideally several weeks before first frost)
Best chemicals (active ingredients)
Pro tips
- Cogongrass spreads via rhizomes—repeat applications are essential.
- Avoid disturbing soil prior to treatment; disturbance can spread rhizomes.
- Monitor treated areas for several seasons and retreat escapes quickly.
Johnsongrass (Sorghum halepense)
Best application methods
- Foliar spot or broadcast treatment
Best timing
- 18 inches → early flowering
- Fall treatments can help suppress rhizomes in established patches
Best chemicals (active ingredients)
- Sulfosulfuron
- Other selective grass herbicides (where labeled and appropriate for your use site)
Pro tips
- Don’t spray immediately after mowing—allow regrowth for better uptake.
- Fall applications can improve long-term suppression by hitting underground reserves.
- Seedbank management and follow-up scouting are critical for lasting control.
Sericea Lespedeza (Lespedeza cuneata)
Best application methods
- Foliar broadcast or spot treatment
Best timing
- Early summer during active growth
- Late summer at bud-to-bloom stage
Best chemicals (active ingredients)
- Triclopyr
- Metsulfuron
- Aminopyralid + metsulfuron combinations (site-dependent)
Pro tips
- Early detection dramatically improves control success.
- Avoid spraying too late after plants harden off.
- Prescribed grazing can help weaken stands before herbicide programs in some settings.
Tree-of-Heaven (Ailanthus altissima)
Best application methods
- Hack-and-squirt / injection
- Basal bark (do not cut first)
Best timing
- Mid-July → mid-October
Best chemicals (active ingredients)
- Triclopyr
- Glyphosate
- Triclopyr + imazapyr (basal bark where labeled)
Pro tips
- Cutting alone often makes infestations worse by triggering root suckering.
- Treat standing trees first, then remove later if needed.
- Prioritize seed-producing females to reduce future spread.
Bradford / Callery Pear (Pyrus calleryana)
Best application methods
- Cut-stump for mature trees
- Basal bark for smaller stems
- Foliar for seedlings and saplings
Best timing
- Mid → late summer for foliar
- Cut-stump: treat immediately after cutting
Best chemicals (active ingredients)
Pro tips
- Ornamental escapes spread rapidly via birds—control seed sources when possible.
- Treat young trees early before thorny thickets form.
- Follow up annually for new seedlings from the seedbank.
Japanese Knotweed (Reynoutria japonica)
Best application methods
- Foliar treatment
- Stem injection where appropriate
Best timing
- Late summer → early fall
- Late August → early September often provides best results
Best chemicals (active ingredients)
- Glyphosate
- Imazapyr (use-site restrictions apply)
Pro tips
- Plan for multi-year control programs and follow-up monitoring.
- Avoid mowing before treatment—it reduces leaf area and herbicide uptake.
- Use extra caution near water and sensitive habitats; always follow label restrictions.
Privet (Ligustrum spp.)
Best application methods
- Cut-stump for large shrubs
- Foliar for seedlings and small plants
- Basal bark for multi-stemmed plants
Best timing
- Late fall → winter for cut-stump
- Avoid early spring sap flow for woody treatments
Best chemicals (active ingredients)
Pro tips
- Privet thrives in shade—dense infestations require follow-up scouting and retreatment.
- Treat before fruiting to reduce seed spread.
- Mechanical removal without herbicide is rarely successful long-term.
Russian Olive (Elaeagnus angustifolia)
Best application methods
- Cut-stump
- Girdle and treat
- Basal bark
Best timing
- Late summer → fall
- Some winter treatments remain effective in milder conditions
Best chemicals (active ingredients)
Pro tips
- Focus on riparian corridors first to slow the spread downstream.
- Remove seed-producing trees early to reduce re-infestation pressure.
- Combine mechanical removal with targeted herbicide follow-up for best results.