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§ Field Guide
Chemical Control
Safe herbicide handling for conservation practitioners
A working field guide to personal protective equipment, herbicide label literacy, and safe handling, mixing, and pouring practices. Written for practitioners applying herbicides in Hawaiian conservation contexts.
By UH Ecosystems & Landcare ProgramPublished October 2024chemical control · herbicide · safety · PPE · weed control
§ 01 · Personal Protective Equipment (PPE)
Personal Protective Equipment (PPE)
Everyone involved in a pesticide field operation is at risk of exposure to hazardous chemicals. PPE addresses the risk to eyes, face, feet, hands, legs, and body when handling and applying herbicides.
General How-To
The minimum required PPE, as specified by the pesticide label, is to be worn at all times when handling and/or applying herbicides.
Common PPE includes nitrile gloves, long-sleeved shirt, long pants, closed-toed shoes, and safety glasses.
- Use chemical-resistant gloves. Never wear cotton or leather gloves — they absorb chemicals. Check herbicide labels for material and thickness requirements.
- PPE is the outermost layer. Keep pants over boots and wear loose-fitting clothes. Unless the application method requires otherwise, sleeves are best tucked into gloves.
- Additional PPE may be worn as long as it does not cause additional safety concerns and can be worn with comfort and ease.
Coveralls provide extra protection for the applicator over their work clothes. Use with caution — they are not made of breathable material and the user may be at risk of overheating, especially in hot conditions.
Respirators provide additional protection when doing foliar sprays. Their use requires approval by a medical expert to confirm the applicator is healthy enough to use it safely. Respirators vary in protection efficacy (e.g. droplet size); use the appropriate respirator for the type of application. Respirators must be properly fitted to the applicator.
Respirator Fitting — by Island
Vendors that provide respirator fitting services across Hawaiʻi.
Kauaʻi
Contact needed — please suggest a vendor.
Maui
Contact needed — please suggest a vendor.
Hawaiʻi Island
Contact needed — please suggest a vendor.
Outer surfaces of herbicide containers are considered contaminated. Gloves should be worn when moving pesticide containers, and should be removed before touching non-herbicide objects to prevent contamination.
Two techniques for safe glove removal:
1. Wash gloved hands with soap before removal.
2. Turn one glove inside out, with the other glove tucked inside (so the outward-facing surfaces of both gloves are touching).
Further Reading
- 01
- 02Pesticide Environmental Stewardship — PPE →Pesticide Stewardship
Covers labels and PPE, selection, components, cleaning, maintenance, storage, disposal, plus NIOSH presentations and video training.
PPE Requirements — Commonly Used Herbicides
| Product | Active Ingredient | Minimum PPE | REI |
|---|---|---|---|
| Garlon 4 Ultra | Triclopyr ester | Gloves, long sleeves/pants, closed shoes, eyewear | 12 hr |
| Garlon 3A | Triclopyr amine | Gloves, long sleeves/pants, closed shoes, eyewear | 48 hr |
| Roundup Pro | Glyphosate | Gloves, long sleeves/pants, closed shoes, eyewear | 4 hr |
| Milestone | Aminopyralid | Gloves, long sleeves/pants, closed shoes, eyewear | 4 hr |
§ 02 · Herbicide Labels
Herbicide Labels
The label is a legal document. Reading it carefully is both a professional responsibility and a core safety practice.
Overview
Herbicide labels provide critical — and legally required — information regarding safety and first aid, mixing, storage, cleaning, disposal, and application (methods and targets) of any one herbicide.
It is good practice to be familiar with the labels of the herbicides that you use. Any programmatic mixing, storage, cleaning, disposal, and application instructions should reflect the requirements on the herbicide label.
Further Reading
- 01Unit 2 — Pesticide Labels →CTAHR Pesticides Extension Program
From the HDOA RUP Applicator Certification Study Guide.
§ 03 · Basic Handling, Mixing, and Pouring
Basic Handling, Mixing, and Pouring
The most dangerous part of applying herbicide is handling concentrated chemicals. Dermal exposure to a small amount of concentrated herbicide can equal a full day of exposure in a treated field.
Planning
Prior to conducting an herbicide operation, all staff shall be briefed on:
- Management goal
- Target weed species
- Location of herbicide operation
- Safety protocols
Be aware of weather conditions to enable effective decision-making around starting and stopping an operation.
Further Reading — Handling Decisions
- 01
Equipment Maintenance
Be aware of the integrity of your equipment. Never use damaged equipment or out-of-date materials.
- Check equipment and fittings for leaks.
- Calibrate with water before using herbicides.
- Evaluate the status of application and containment equipment during decontamination — render damaged equipment unusable to prevent future use if immediate disposal is not feasible.
- Flag damaged items: tear Ziplocks or gloves with holes, mark dry bags, write on containers with messages like "broken" or "to toss".
Consider developing a maintenance schedule for all herbicide equipment — backpack sprayers, handpumps — to ensure the equipment stays in working order. Herbicide equipment is costly to repair or replace and needs to be in excellent working condition for safe operations.
Designated Mixing Areas
Whether at the base yard or in the field, establish a mixing area. Herbicides should be mixed only in pre-designated areas — preferably near the storage site.
A good mixing area is:
- Well-ventilated
- On a clear, level surface
- Low-traffic
- Away from food or laundry
- Away from ponds, streams, wells, or drainage ditches
Pouring and mixing should be done prior to going into the field whenever possible. Exceptions include mixing solutions for power, backpack, hand, or pump sprayers in the field, or herbicide to be used during camp trips. Never mix, load, or clean equipment near surface water.
Field Mixing
When mixing must occur in the field, complete as near the treatment sites as possible but away from non-target plants and water sources. Ideal field mixing sites:
- Have few native or other desirable species
- Are not susceptible to erosion or runoff
- Are rarely — if ever — visited by the public
- Provide easy access for containment and clean-up of spills
Be aware of spill response procedures to effectively react to accidental spills.
§ 04 · Before You Spray
Before You Spray
A field-ready checklist, a live comparison of approved herbicides, a treatment-selection decision tree, and a live index of every chemical treatment in this node's archive.