Forester Ron Lan outlines herbicide strategies, wetland limits and licensing for invasive‑plant control

Ron Lan, a forester and vegetation‑management sales consultant with Nutrient Solutions, told attendees that herbicides are one tool within an integrated pest‑management strategy for invasive‑plant control and described how to match chemistry and technique to site, species and weather.

Lan opened with his credentials and scope of work, saying, “I consider myself a Forester that sells herbicides,” and explained that his recommended approach begins with diagnosis: understand why the invasive is present, set aesthetic or ecological thresholds, and monitor before applying treatments.

Why it matters: Lan said choosing the right herbicide requires knowing its mode of action (how it acts in the plant), whether it is selective or non‑selective, and whether it is residual (persists in soil) or non‑residual. He advised combining products with different mode‑of‑action numbers to reduce resistance and improve efficacy.

On specific products and techniques, Lan used glyphosate as an example of a non‑selective, foliar systemic herbicide that is non‑residual in soil and said it is often effective late in the season when plants send sugars to roots. He recommended triclopyr (Garlon formulations) and growth regulators for early‑season control of broadleaf invasives, and said products such as Escort and Milestone can be useful in mixes but have more soil residual activity and therefore higher risk to overstory trees if applied carelessly.

Application advice: Lan described common equipment (mist blowers on skidders for dense understory, ATV/boom rigs for broadcast work, and low‑volume backpacks for spot treatments). He outlined cut‑stump, basal‑bark and injection techniques for larger stems and recommended prompt treatment of cut stumps (typically a 50/50 herbicide:water mix for water‑based products) to prevent resprouting.

Timing and selectivity: He emphasized timing as a tool for selectivity. "Non‑selective herbicides can be made effectively selective by timing applications when native plants lack foliage but invasives still hold leaves," he said, describing late‑season foliar windows for species such as honeysuckle and common buckthorn.

Knotweed: For knotweed, Lan recommended weakening root reserves by cutting in early summer, then following with late‑season glyphosate or a combination of herbicides (different modes of action) to improve control.

Wetlands and permitting: Lan said Maine allows individual‑plant, non‑broadcast treatments up to wetland edges if the product label and state rules permit it, but cautioned that state regulations can be stricter than federal labels. He advised consulting the Maine Board of Pesticide Control and obtaining variances or permits where necessary.

Licensing and purchase rules: Lan summarized applicator licensing: commercial licenses are required for paid work on property you do not own (including public parks and government property); private applicators may apply general‑use pesticides on property they or their employer own or lease. He cited a three‑year commercial license fee example of $105, a minimum passing score of 80 on core/category exams, and continuing‑education credit requirements for operators and masters.

Weather risks and drift: Lan warned that rain or heavy dew reduces uptake and that wind, droplet size, temperature and humidity affect drift and volatility. He noted ester formulations (for example, Garlon 4) can volatilize on hot, low‑humidity days and advised choosing amine or lower‑volatility formulations or delaying application to reduce off‑site movement. He also cautioned about temperature inversions and cited a Maine guidance against applying when winds are below roughly 2 mph to avoid inversion‑related drift.

Closing: Lan reiterated that herbicides are not a silver bullet but a component of IPM, and told attendees a PDF of the presentation and his contact information would be made available for follow‑up.

The presentation combined practical, species‑specific prescriptions (product mixes and timing) with reminders about label directions, Maine permitting, and applicator licensing.