Module TwoChap. 4, 5, & 6

Chapter 4Soil and Pest Factors ThatInfluence Fumigant Activity

Factors that Influence Soil Fumigation

• Pest Factors:– What are they (pest identification)?– Where are they (how deep)?– When to fumigate (application timing) ?– How much gas to use (fumigation rate)?

Correct diagnosis is the first step in successful disease management!

Factors that Influence Soil Fumigation

Factors that Influence Soil Fumigation:Application Depth

• Fumigating when soil temperatures are higher also catches pest & pathogens at growth stages when pests & pathogens are more active, when they are more susceptible to soil fumigants.

Factors that Influence Soil Fumigation:Application Timing

The appropriate fumigant, its application rate, application method, & timing are determined by:

• The crop to be planted;

• The target soil-borne organism(s) – “pests”;

• Level of infestation;

• Soil characteristics, such as texture;

• Environmental conditions.

Fumigator Set-up, Repair & Maintenance

• Check fittings and tubing to ensure all are made of materials compatible with the fumigant to be used; never aluminum;

• Filters in all systems, check valves in pressurized systems.

Factors that Influence Soil Fumigation:Soil Characteristics

SoilParticle

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Factors that Influence Soil Fumigation:Soil Temperature

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• Soil temperature influences how fast fumigants change from a liquid into a gas;

• Gases move through soil faster than liquids;

• The higher the soil temperature, the faster fumigants vaporize into a gas;

• The higher the soil temperature, the further the fumigant often moves – through soil, but also potentially into the air above the ground.

• Acceptable soil temperatures at the point of injection usually between 40o and 90o F.

• If air temperatures have been above 100o for within 72 hr of application, soil temperatures at application must be recorded.

Factors that Influence Soil Fumigation:Soil Temperature

Factors that Influence Soil Fumigation:Soil Texture

Factors that Influence Soil Fumigation:Soil Texture

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• Coarser soils (sands, sandy loams) have larger soil particles & larger spaces between them (pores);

• Fumigants can move through larger soil pores faster;

• The coarser the soil, the faster & further fumigants move, both through soil and into the air;

Factors that Influence Soil Fumigation:Soil Moisture

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• Soil moisture influences how far & how fast fumigants move;

• Soil moisture requirements vary for fumigants depending upon their vaporization rate and water solubility;

• The coarser the soil, the faster & further fumigants move through soil;

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• Soil moisture influences how far & how fast fumigants move;

• Coarser textured (sandier) soils typically require higher moisture contents than finer-textured soils (clays, silts).

• Soil moisture requirements vary for fumigants depending upon their vaporization rate and water solubility;

Factors that Influence Soil Fumigation:Soil Moisture

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• The coarser the soil, the faster & further fumigants move through soil;

• Determine soil moisture with a tensiometer or by the USDA feel & appearance method.

Factors that Influence Soil Fumigation:Soil Moisture

“USDA Feel & Appearance Method”or “Clod Method”

• 50-75% Moisture in Fine Sands/Loamy Sands:When darkened soil forms a moist ball with loose &

clustered sand grains on fingers, with moderate water staining on fingers; will not ribbon.

Photo courtesy USDA-NRCS

“USDA Feel & Appearance Method”or “Clod Method”

• 50-75% Moisture in Sandy Loams: when Darkened soil forms a ball with defined finger marks, very light soil/water staining on fingers, not sticky.

Photo courtesy USDA-NRCS

“USDA Feel & Appearance Method”or “Clod Method”

• 50-75% Moisture in Sandy Clays & Clay Loams: when darkened soil forms a ball, very light staining on fingers, pliable, & forms a weak ribbon between thumb & forefinger.

Photo courtesy USDA-NRCS

• Soil Tilth = the physical condition of soil– Factors = clods, moisture content, aeration, water

infiltration, & drainage; – Clods & hardpans have less pore space, slowing and

reducing fumigant movement, but increasing off-gassing;– Best soil tilth for fumigation = physical condition that

allows the fumigant to diffuse through soil but not escape when the soil surface is sealed properly.

Factors that Influence Soil Fumigation:Soil Tilth

Pi = ~844 eggs/500 cc soil

Factors that Influence Soil Fumigation:Crop Residues

• Slow fumigant movement by absorbing some fumigants;

• Break the seal at the soil surface, providing avenues for gas to escape from the soil;

• Hang-up on fumigator shanks, plugging outlets.

• For less volatile fumigants, by compacting soil or irrigation (~1/4” water)

Factors that Influence Soil Fumigation:Soil Sealing

Factors that Influence Soil Fumigation:Soil Sealing

• By tarping for more volatile fumigants (methyl bromide, some chloropicrin applications).

Review Questions

Which of the following soil factors has little or no effect on the fumigant’s movement

through the soil?

1. Tilth

2. pH

3. Texture

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A fumigant handler is intending to apply a 1,3-D/chloropicrin product to a sandy loam field. Soil

temperature at the depth of the application is 45°F, and the soil forms a weak ball using the “feel method.” Which of the following may limit the success of this

fumigation?

1. Soil texture

2. Soil moisture

3. Soil temperature

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Which of the following pest factors has the greatest impact on the timing of a soil

fumigant application?

1. Pest density

2. Difficult-to-control pests

3. Growth stage of an insect.

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Chapter 5Personal Protective Equipment

and Respirators

Personal Protective Equipment (PPE)

• Fumigants are distinct from other pesticides – fumigants are volatile – may result in inhalation exposure.

• Therefore PPE required differs from non-fumigants

• Check the pesticide label PPE directions in the Precautionary Statements section of the pesticide label.

Differences in PPE for Fumigants

• Examples of how PPE for various fumigants may differ from non-fumigants:– Respirators are always required to be

kept on site– Loose-fitting work clothes– Often no chemical-resistant apron or

spray suit– May not allow Chemical-resistant gloves

or boots – May require wearing cotton gloves– Others may specify chemical-resistant

gloves and footwear just for certain tasks.– Specific about the type of eye or

respiratory protection to wear and when

Respirators

• Medical Evaluation Before Respirator Fit Testing– preliminary screening, – a medical practitioner may determine that a

physical exam is required.

• Re-examined if – health status, – respirator style,– use conditions change.

Respirators

• May be required for:– Any handling task– Triggered by sensory irritation

• Not required:– Prior to application of the fumigant– When transporting unopened cylinders

Respirator Fit and Care

• After being cleared for:– Air-purifying respirator (APR)

• Fumigant handlers must be – Fit tested and trained on how to use each

specific respirator – Fit testing is required and repeated annually.

Respirator Fit and Care

• Follow-up fit testing is required if:– The style of the face piece has changed.– The respirator size, model, or brand has

changed.– There is a physical change in the person’s

face due to weight change or dental work. – Fit is unacceptable.– At request of the user.– Employer policy.

• Fit check before each use (user seal check)

Respirator Training

• Adequate training is required before handling a fumigant, including:– Fit and use of the respirator– Even if it is for emergency response only

• Must establish a formal respiratory protection program, including:– Written operating procedures for

• maintenance,• cleaning, • storage

Respirator Types

• APR (Air Purifying Respirator)– replaceable organic

vapor cartridge or – canister(gas mask) – half-face/fullface

• PAPR (powered)• SCBA

(Self-Contained Breathing Apparatus)

Selection

• Carefully review the respirator requirements on the label to determine:– Whether you need respiratory protection.– Correct type of respirator for that fumigant.– Situations when respiratory protection is

needed.

• Never substitute another type of respirator

Cartridge or canister life

• The type of cartridge.• The size of the cartridge.• The type and concentration of vapors in the

surrounding air.• The length of exposure.• The rate of breathing. • Whether more than one contaminant is present.• The temperature and humidity at the time of

use.

Cartridge Replacement (also a WPS Requirement)

• At the first indication of odor, taste, or irritation.• According to the pesticide label or manufacturer

instructions, whichever is more frequent.• When the end of service life indicator (ESLI)

shows a color change indicating the unit has expired.

• In absence of any of the above instructions or indications of service life, at the end of each day’s work period.

SCBA

• SCBA respirators are only used – For emergency situations and – Not permitted for routine handler tasks.

Review Questions

Who must undergo a medical evaluation before using respiratory equipment?

1. Fumigant handlers with known heart problems.

2. Fumigant handlers who will be removing tarps.

3. Any fumigant handler or certified applicator who might need to wear a respirator. 1 2 3

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Which type of respirator may never be worn during routine fumigant handler tasks?

1. Half-face air purifying respirator (APR)

2. Powered air-purifying respirator (PAPR)

3. Self-contained breathing apparatus (SCBA)

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How do soil fumigant labels differ from nonfumigant labels regarding personal

protective equipment (PPE) statements?

1. Respirators are always required on site

2. Different products have different PPE requirements

3. PPE requirements will vary depending on the handling task

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Chapter 6Protecting People

“Stop Work” Trigger Levels and Respiratory Protection

• Fumigant labels specify trigger levels which require fumigant handlers to– Continue work using a respirator, or – Stop work and leave the application block and

buffer zone.

• Prevents fumigant handlers from being exposed to the maximum-use concentration (MUC) (capacity of the respirator cartridge)

Examples of Label Requirements

• An APR with the appropriate cartridges or canisters must be available for each fumigant handler who may be required to wear a respirator.

• For methyl bromide formulations with more than 20% chloropicrin, 100% chloropicrin formulations, dazomet, metam sodium, and metam potassium, fumigant handlers only need to wear full-face or gas-mask type respirators when they experience sensory irritation. If this happens, fumigant handlers must either stop work and leave the area, or use a full-face APR to complete the task.

Minimum number of fumiganthandlers and respirators that must

be on site:

• Methyl bromide, chloropicrin only, and other products with chloropicrin:– At least two fumigant handlers must be on

site.– At least two APRs must be on site.

• Metam Sodium & Metam Potassium:– One fumigant handler on site.– One full-face APR must also be on site.

Stop Work Triggers

• Trigger levels and air-monitoring requirements are found on labels under the “Respiratory Protection and Stop Work Triggers” section.

Sensory Irritation

• A physical reaction to a certain fumigant air concentration, including…– burning or irritation of the

• eyes, • nose, or • mucous membranes.

• If at any time there is sensory irritation handler must:– Use an APR to complete the task, or– Stop work and leave the application block and

buffer zone.

Air Monitoring• Two things can initiate the need for air

monitoring to start immediately:– Whenever a fumigant handler is wearing an APR.– Sensory irritation.

• Air samples must be collected at least every– 2 hours – in the breathing zone of the handler performing a

representative task

• The breathing zone is the area within a 10-inch radius of the nose and mouth.

Returning to work without APR

• After a trigger level has forced work to stop, handlers cannot re-enter the application site or buffer zone area until:– Two consecutive air monitoring samples taken

in the fumigant handler’s breathing zone and 15 minutes apart are below the specified trigger level.

– Fumigant handler does not experience sensory irritation.

Monitoring RepresentativeHandler Activities

• Activities to be sampled must represent each handler’s exposure occurring within the application block; i.e.– Tractor driver– Co-pilot– Shoveler

Air-Monitoring Devices• Gas detector tubes• disposable and can be used only once.• Must use pump and tubes from the same

manufacturer• Tubes deteriorate with age. • Some tubes have a shelf life of two years

when stored at room temperature. • Deterioration is more rapid above 86°F.• Direct sunlight affects the chemical

reagents in the tubes.• At low temperatures—at or below freezing

—tubes may not give reliable readings. Warm the tubes to room temperature before use for best performance.

• Tubes may have cross‑sensitivity to gases other than their target gas. Seek this information from the manufacturer.

Emergency Preparednessand Response

• If homes or businesses are near a buffer zone, the certified applicator-in-charge has two options:– Option 1: Monitor the buffer zone.– Option 2: Provide response information to

neighbors

• Certified applicator may choose the option• If the buffer zone is 25 feet then emergency

preparedness measures are not required

Option 1 – Monitor the Buffer Zone

• Monitor between the Buffer Zone and the home or business of concern.

• Monitor at least four times each day throughout the buffer zone period:– 1 hour before sunset on the day the application

begins,– once during the night,– once at 1 hour after sunrise, and– once during the day.

• Over the course of the 48-hour buffer zone period, monitoring will occur eight times.

OPTION 2: Provide EmergencyResponse Information to Neighbors.

• Information to neighbors provided at least one week before the application including:– The location of the application block.– Basic information about the fumigant product.– Contact information for the certified applicator

and property owner.– When the fumigation and the buffer zone period

will occur (must not be more than four weeks away).– Early signs and symptoms of exposure, and what

to do if exposure is suspected (call 911 in most cases).

Method of Notification

• Provide this information using any method that effectively communicates the required material to the neighbors.– telephone, – door hangers,– mailings, or – email. – May not use mass media (radio, TV, Newspaper Ad)

• It is a good idea to attach a copy of the information provided to the FMP as a record.

Emergency Response Plan

• Plan must be initiated:– If handler experiences sensory irritation,

or air monitoring detects concentrations of concern outside of the buffer zone.

Fumigant Poisoningand First Aid

• Fumigant poisoning can occur from contact with the skin, eyes, or tissues in the mouth or nose.

• Seek immediate professional medical attention if anyone experiences an exposure to a fumigant.

Review Questions

If a fumigant handler who is NOT wearing an air purifying respirator (APR)

experiences sensory irritation, he or she has two choices. What are they?

1. Stop working and leave the area or use an APR to complete the task.

2. Use an SCBA or take air-monitoring samples from the breathing zone.

3. Stop working and leave the area or ask the certified applicator-in-charge to finish the task. 1 2 3

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The lower trigger level on a fumigant label is 1 ppm and the upper trigger level is 5 ppm. Air-monitoring samples show a

fumigant concentration of 2.2 ppm in the area where fumigant handlers are working. Which of the following actions are

correct?

1. Continue air monitoring to see whether air concentration levels reach the upper trigger level.

2. Reseal the soil where necessary to prevent further fumigant off-gassing.

3. Require fumigant handlers to either put on a respirator or leave the application block and buffer zone.

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Labels typically require how many air-monitoring samples show that air concentrations of the

fumigant are below the trigger level, and allow fumigant handlers to remove their APRs?

1. One

2. Two

3. Five

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How large is the breathing zone around the nose and mouth?

1. 6-inch radius.

2. 10-inch radius.

3. 24-inch radius.

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What is the purpose of a trigger level?

1. To determine when respirators must be available on site.

2. To prevent the fumigant handlers from being exposed to maximum-use concentrations (MUC’s).

3. To stop the application until the fumigant concentration level falls below the trigger level.

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