5.7 Application Methods & Equipment Selection
Key Takeaways
- Application method describes where the product is placed — broadcast, band, spot, directed, foliar, soil, seed, bait, or space treatment — and the choice drives product volume, exposure, drift risk, and cost.
- Band application treats only a strip over or between rows, so the product actually applied per treated acre stays at the labeled rate while the amount purchased per field acre falls in proportion to the band width.
- Spot and directed treatments limit the pesticide to the target and away from the crop, but they raise handler exposure because the applicator is close to the spray.
- Chemigation applies pesticide through irrigation water and carries two Minnesota-specific duties: the site must be posted throughout the treatment period, and a compliant backflow prevention device is required when filling from a public water supply or public waters.
- Fumigation is the highest-hazard method in the trade because the product is a gas that gives no protection from ordinary PPE, requires the appropriate Minnesota category, and cannot be delegated to a noncertified applicator.
5.7 Application Methods & Equipment Selection
Two applicators can use the same product at the same rate and get completely different results, costs, and exposure — because they placed it differently. Application method is the decision about where the product goes; equipment is what carries out that decision. Labels frequently restrict which methods are permitted, and under FIFRA an application method is legal unless the label prohibits it, so the label is always the starting point.
Methods That Describe Coverage of the Area
| Method | What It Is | Why You Would Choose It |
|---|---|---|
| Broadcast | Uniform application over an entire area | Standard for field-wide weed, insect, and disease pressure; simplest to calibrate |
| Band | A strip over or between crop rows, leaving the rest untreated | Cuts the amount of product purchased per field acre in proportion to the band width, while the treated strip still receives the full labeled rate |
| Spot | Treating small, discrete infestations only | Least product, lowest environmental load; ideal for scattered perennial weed patches |
| Directed | Aimed at a specific part of the plant or at the soil beneath it, avoiding the crop foliage | Lets a non-selective product be used selectively |
| Shielded / hooded | A physical shield keeps spray off the adjacent crop | Between-row herbicide work in sensitive crops; also reduces drift |
| Basal / basal bark | Applied to the lower stem or trunk | Woody plant and brush control on rights-of-way and in natural areas |
The Band Application Calculation
Band treatment is the method most often tested with arithmetic. The key idea: the rate on the treated strip does not change — you simply treat less area.
Product per field acre = broadcast rate × (band width ÷ row spacing)
Example: a 15-inch band on 30-inch rows treats half the field. At a broadcast rate of 2 pints per acre, you buy 2 × (15 ÷ 30) = 1 pint per field acre, but every square foot inside the band still receives the full 2 pints-per-acre rate.
Methods That Describe the Target Surface
- Foliar — applied to leaves and stems. Coverage requirements depend on whether the product is contact or systemic.
- Soil surface — applied to the soil and left on the surface; may require rainfall or irrigation for activation.
- Soil incorporated (preplant incorporated) — mixed into the soil mechanically. Reduces volatilization and photodegradation, and places the product in the germination zone.
- In-furrow — placed in the seed furrow at planting.
- Sidedress / banded at cultivation — placed beside the row during the season.
- Seed treatment — applied to the seed before planting; the smallest total quantity of any method, but it carries its own dust-off and pollinator considerations and requires Category H for commercial seed treatment work in Minnesota.
- Soil drench and soil injection — a liquid poured or injected into the root zone; common for tree and shrub systemics.
- Trunk injection / tree injection — placed directly into the vascular system, essentially eliminating drift. Widely used in Minnesota for emerald ash borer treatment.
Methods for Structures and Enclosed Spaces
- Crack and crevice — a small amount placed directly into cracks, voids, and openings where pests harbor. The defining structural pest control technique because it puts product where pests are and where people are not.
- Void treatment — dust or aerosol injected into a wall or equipment void.
- Perimeter treatment — a band around the outside of a structure.
- Baiting — a food attractant plus a toxicant, taken by the pest to where it lives. Extremely target-specific; rodenticide baits must be placed in tamper-resistant stations where children, pets, or non-target wildlife could reach them.
- Space treatment / fogging and ULV — very fine droplets released into an enclosed air space. High coverage, and the highest inhalation hazard of any non-fumigant method.
- Fumigation — a true gas that penetrates the entire treated space or commodity. This is the highest-hazard method in the trade: PPE that stops a liquid does nothing against a gas, respiratory protection requirements are specialized, monitoring and placarding are mandatory, and the work requires the appropriate Minnesota category (N for non-soil fumigation, O for soil fumigation, or the SPCA fumigant endorsement). Fumigation is not a task that may be delegated to a noncertified applicator working under supervision.
Chemigation
Chemigation applies pesticide through an irrigation system. It covers large areas with no wheel traffic, but it links a pesticide tank directly to a water system, which is why it carries specific legal duties in Minnesota:
- Posting — Minn. Stat. 18B.07, subd. 3: sites being treated through irrigation systems must be posted throughout the period of pesticide treatment, in accordance with labeling and rules adopted under Chapter 18B.
- Backflow prevention — Minn. Stat. 18B.07, subd. 5: application equipment may not be filled directly from a public water supply or from public waters without a backflow prevention device that complies with the Minnesota Plumbing Code (Minn. R. Chapter 4714), and cross connections are prohibited.
- Label authorization — chemigation is permitted only if the label allows it, and labels that do allow it specify the required safety interlocks.
Matching Equipment to the Method
| Equipment | Delivers | Notes |
|---|---|---|
| Boom sprayer | Broadcast and band foliar or soil applications | The workhorse; uniformity depends on nozzle spacing, height, and overlap |
| Boomless nozzle / handgun | Rough terrain, rights-of-way, spot work | Less uniform; pattern width changes with pressure |
| Backpack and hand sprayer | Spot and directed treatments | Highest applicator proximity — wear the mixing-grade PPE |
| Airblast sprayer | Orchards, vineyards, tree lines | Uses an air stream to carry droplets into a canopy; 100-foot AEZ under the WPS |
| Wick / wiper applicator | Contacting tall weeds above a crop canopy | Makes a non-selective herbicide behave selectively; essentially no drift |
| Granular spreader (rotary or drop) | Dry granules and baits | Rotary spinners cover quickly but throw off-target near edges; drop spreaders are precise but slow. Calibrate by weight, not by the setting number |
| Aerial (fixed-wing, helicopter, UAS) | Broadcast where ground equipment cannot travel | Requires Category B plus Category A and one other; highest drift-management burden; 100-foot AEZ |
| Fogger / ULV applicator | Space treatments | Fine droplets, high inhalation risk, enclosed-space or specialized outdoor use |
| Bait station | Rodenticides and some insect baits | Tamper-resistant stations required where children, pets, or non-target wildlife have access |
| Injection equipment | Tree and soil injection | Near-zero drift; slower and site-by-site |
The Exposure and Drift Trade-Off
Methods that reduce environmental exposure often increase applicator exposure, and the reverse. Spot spraying with a backpack puts far less product into the environment than a broadcast pass, but the applicator is standing in the spray. A closed-cab boom sprayer protects the operator well but treats every square foot. A wick applicator does both well but is slow.
Choose deliberately, and let the choice show up in the rest of the job: the method determines which PPE the label requires, which spray quality you need, how large the Application Exclusion Zone is, and how you will calibrate. A band application calibrated as a broadcast application is over-applied by exactly the factor you thought you were saving.
An applicator applies a 15-inch band over 30-inch rows using a product whose broadcast rate is 2 pints per acre. How much product is needed per field acre, and what rate does the treated strip receive?
Which two Minnesota requirements apply specifically to chemigation?
Why is fumigation treated as the highest-hazard application method?
Which application method places the pesticide directly into the harborage areas where structural pests live while minimizing exposure to building occupants?
You've completed this section
Continue exploring other exams