Integrated pest management: an SOP
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Integrated pest management: an SOP

This standard operating procedure (SOP) shows how to prevent pests and diseases in a cannabis grow room. It also shows how to scout and when to start a treatment. It shows how to use predators and sprays and how to keep complete and correct records.

OperationsGuide for operations5 sources~14 min to read
In this paper
01 Purpose and scope02 Definitions03 Evidence and limitations04 Scouting procedure05 Action thresholds06 Biological control07 Spray rotation and how to spray safely08 Sanitation and quarantine09 IPM tasks for each day, decision flow and records10 Troubleshooting and usual results11 References
Start here

Purpose and scope

Jurisdiction
Jurisdiction note: The approval of products, the approval of organisms, the REI and the PHI (pre-harvest interval) are local. For example, NZ uses ACVM, HSNO and WorkSafe, and the US uses EPA WPS. Before you spray or release predators, examine the current regulations and the labels.

Integrated pest management (IPM) is the regular procedure in which you find pests and diseases before they move to more plants. You use the weakest treatment that gives a good result. You use a stronger treatment only when it is necessary.

IPM is not one spray. IPM is not one task to release predators. It is a loop: examine the plants, make a decision, do a treatment, and do the loop again. Do the loop in each room. Start with the mother plants and the clones. Continue to the vegetative stage and the flowering stage.

One mite colony that you do not find, or one outbreak of powdery mildew, can destroy all the harvest[1]. In a regulated facility, an error when you use a pesticide can cause an unsatisfactory result in the residue test. As a result, you discard all the batch[2]. This guide is for a person who does not know IPM. The guide gives the definition of each term where the term first occurs.

The IPM loop1Scoutwalk and examinethe plants→2Identifyfind the pest ordisease name→3Thresholdcompare with thethreshold→4Selectscout, release,spray, remove→5Applyuse the weakesttreatment thatis sufficient→6Recordrecord, thenscout again
Figure 1. IPM is a loop that you do again and again. It is not one treatment. Each finding goes around the loop and then back to the step Scout.
The most important information

Use the weakest treatment that gives a good result. Use a spray only when the action threshold makes it necessary. If you find a problem when it is small, the correction is easy. A problem that you do not find can destroy all the crop.

Terms

Definitions

This section gives the terms before the procedure. It is not necessary to know all of the terms at this time. Each term occurs again in the sections that follow.

ScoutingA careful visual inspection of the plants for pests, damage or disease.
Action thresholdThe quantity of pests at which you start a specified treatment.
Biological control (biocontrol)A method in which you release predators (insects or mites) to eat the pests.
Foliar spray and drenchA foliar spray is a liquid that you apply to the leaves and stems. A drench is a liquid that you apply to the root zone.
REI (re-entry interval)The time after a spray before a person can safely go into the room.
Withholding periodThe time after a treatment before you can harvest the crop for sale.
QuarantineThe procedure in which you keep new plants, or plants that can have a pest or disease, isolated from the crop. You monitor the plants before you move them to the crop.
FrassThe waste of insects. It is a visual sign of a pest, and you can see it before you see the pest.
Time from the spray to the harvest1Applyspray, thenrecord it→2REIno person goesin until theinterval ends→3Withholding periodno harvest untilthe period ends→4Safeyou can go inand harvest
Figure 2. Two time periods start at the time that you spray. One time period is for persons (REI) and one time period is for the crop (withholding period).
Quality of the information

Evidence and limitations

Three types of information

We want each paper to be correct. Thus we examine each paper for information that is not solid. This information comes from the view of one grower, from a small number of sources, or from grower methods that have no controlled test. We identify this information, and we do not show it as solid.

Frequently there is no paper for the decision that you must make. Then we use the reports of other growers and the methods that work in the rooms that we know. This information can help you, but it is not the result of a laboratory test. Use the methods that work for your plants, for your room and for your meters. If a table does not agree with your crop, use the data from your crop and record the difference.

Solid
Tests of plants, specifications or many sources that agree show that the information is correct
  • The IPM hierarchy is prevent, monitor, soft controls and hard controls.
  • The rate on the label and the legal status of a product control each spray.
Grower method
Many growers use this method in their rooms. Start with it, then change it for your room.
  • Intervals for scouting and examples of action thresholds.
Weak
The view of one grower, a small number of sources, one test, or a method that works in one room
  • Rates for pesticides in kitchen volumes. Do not use them. Use only the rate on the label.
  • A limit of day 21 for foliar sprays as a general fact. The limit is a quality SOP and not a regulation for all areas.
  • Biocontrol agents that a grower thinks you can use in all countries.

If you find an error, make a report. We will correct it. Make the report on GitHub, with the name of the paper and the information that is incorrect. If you have a source, include it: Make a report of an accuracy problem. The regulations, labels and licenses of your area always override each procedure in these papers. The label weak in a paper shows the points where the risk of an error is highest.

Primary procedure 1

Scouting procedure

Scouting is the primary task of IPM. All the next steps give a good result only if you find the pests when the problem is small. A good baseline is a visual inspection of a minimum of 5% of the room at each check. The room lead does the inspection and records each finding immediately. IPM scouts, who do only this task, do inspections with higher precision[1].

Scout in the same sequence each time. First, examine the tables and the substrate for frass and debris. Then examine the stalk and the stems. Then examine the bottom side of the leaves, where mites and thrips stay out of view. Last, examine the top side of the leaves.

Yellow sticky traps at the bottom of the stem and at the height of the canopy catch fungus gnats, aphids and thrips. These traps give a first sign of a problem.

Scouting sequence (bottom to top)11 Substratetrays for frassand debris→22 Bottom trapsticky trap atstem bottom→33 Stalk, stemsexamine them→44 Leaf bottomswhere mites andthrips stay outof view→55 Leaf topsvisual damage→66 Canopy trapsticky trap atcanopy height
Figure 3. Always scout in the same sequence, from the bottom to the top. A sequence that is always the same makes sure that you examine all the areas when you have a short time.
Sticky traps with dates show a problem at the startA trend that increases (not a stable one) is the first sign. Start a treatment before damage shows.06111622wk 1wk 2wk 3wk 4wk 5insects/trap
Figure 4. Replace one trap each week. Write the date on the trap. Monitor the trend. From week 3 to week 5, the number of insects increases. This change is the signal for an investigation.
Have a loupe with you

You cannot see russet mites and broad mites without a loupe. Use a jeweler's loupe to identify very small pests before you select a treatment.

The scouting loop1Walksame areas, eachday→2Findpest / symptom→3Recordtype, area,severity, photo→4Treatmentapply it, thendo a check againFind the problem when it is small. The records give a trend that you can use.
Diagram. The scouting loop each day: walk, find the problem, make a record, and do the treatment.
Primary procedure 2

Action thresholds

An action threshold changes a finding into a decision. Thus each decision uses data. A model with two parts agrees with a method that commercial growers frequently use[1].

In the first part, you find the first sign of one mite, one aphid or one other pest of the same type. Think that there are more pests. Scout all areas of the room. Start exclusion (limit who goes into the room). Get biocontrol.

In the second part, apply an approved pesticide when more than 3% of the room has pests. This value is an example to start with. Apply the pesticide only if the growth stage and the approval of the manager let you do this. For a zero-tolerance organism, the percentage is not important.

The growth stage also gives a limit for a treatment. Many regulated facilities with soilless substrate control the residue. These facilities apply a treatment to the plants only up to the first stage of flowering. For example, the limit is day 21. Your SOP for PHI and for QA gives the correct limit. After this limit, a weak antimicrobial solution that you use to clean the plants can be the only possible treatment[2].

If a large infestation occurs after day 21 of flowering, remove and destroy the plants that have the infestation. Do not spray.

Four conditions of the action threshold10 pestsmonitor, scoutagain→21 pest foundscout the room,start exclusion,get biocontrol→3>3% have pestsapply approvedpesticide, withapproval→4Large, after day 21remove anddestroy, do notspray
Figure 5. Each condition has a specified treatment. Data on the pest pressure select the condition that applies.
The treatment window in the crop cycleThe growth stage selects the treatment: when the plants have buds, remove them. Do not spray.Mother plants to flower day 21: you can apply a treatmentDay 22 to harvest: no foliar spray050100
Figure 6. The green area is the treatment window. It is the only time when you can apply a foliar spray. The red area is the time to harvest. A spray in the red area can cause an unsatisfactory result in the residue test and crop loss.
Use sulfur only in the vegetative stage

Use sulfur only on mother plants and in vegetative growth. Do not use sulfur in flowering[2]. Sulfur on flowering plants causes contamination of the harvested flower.

Action threshold: apply treatment before the increaseSet a number that starts treatment. Below it, monitor. Above it, apply treatment before the curve increases.monitorapply treatment0491418day1day2day3day4day5day6pests for each plant
Diagram. An action threshold gives a decision from the scouting. Below the threshold, you monitor. Above the threshold, you apply treatment immediately.
Primary procedure 3

Biological control

In biocontrol, you release predators that eat your pests, if the regulations in your jurisdiction let you do this. The predators usually do not cause chemical residue on the cannabis plant at all stages. When there are no more pests to eat, the predators die. Select the correct predator for the pest and for the conditions.

Amblyseius swirskii is a generalist predator. It eats thrips larvae, whitefly and broad mites. It gives the best result at 25 to 30 °C (77 to 86 °F) with humidity of more than 70%[3].

Phytoseiulus persimilis is a specialist predator for spider mites. It eats a maximum of 5 adults or 20 eggs each day. Cool conditions with high humidity are necessary for it[5].

Neoseiulus californicus is an alternative predator for spider mites, for a wide range of temperatures. It stays active at 16 to 32 °C (60 to 90 °F)[4].

Stratiolaelaps scimitus is a mite that stays in the soil. It eats fungus gnat larvae and thrips pupae. Release it when the pest pressure is low, for the best result[1].

Select the predator that is correct for the pest and for the room. Hang sachets or release boxes with the predators in the room. Thus the predators and the material that holds them do not go into the irrigation system.
PredatorTarget pestBest temperatureBest humidityType
A. swirskiiThrips larvae, whitefly, broad mites25–30 °C (77–86 °F)>70%Generalist
P. persimilisSpider mites (the pest number decreases quickly)15–25 °C (59–77 °F)HighSpecialist
N. californicusSpider mites (hot, dry rooms)16–32 °C (60–90 °F)Low or mediumSpecialist
S. scimitusFungus gnat larvae, thrips pupaeRoom temperatureMoist mediaSoil specialist
Figure 7.
Select a spider mite predator for the room temperatureThe ranges overlap. Select the predator for the usual temperature of your room.persimilis (cool, fast)californicus (hot, dry, wide range)swirskii (warm generalist)50°F72.5°F95°F
Figure 8. Read the temperature of your room. Then select the predator that has your temperature in its active range. In a hot, dry room, californicus stays active and persimilis becomes less active.
Predators limit their number

Predators usually do not cause chemical residue. But the regulations in your jurisdiction must let you use the predators, and the predators must be compatible. When there are no more pests to eat, the predators die without a task from you. There is no residue and no withholding period.

Primary procedure 4

Spray rotation and how to spray safely

When the action threshold makes a spray necessary, make sure that the residue is safe and the coverage is good. Do not change the procedure. Use only products that have an approval for cannabis in your jurisdiction. Always obey the dilution and the withholding periods on the label. Do not use a nutrient or supplement that is not on the list of approved products. It can cause an unsatisfactory result in the residue test[2].

Find each value on the current registered label of the product. The values are the spray rate, the interval between sprays, the crop stage, the REI and the pre-harvest interval. Use the label that is correct for the product, the pest and the jurisdiction[7]. A result in an investigation does not give approval for a spray each week or for a spray three times each week.

Use sulfur only when the product has a registration for cannabis. Use it only when the label lets you use it at the crop stage. Do not change a rate to kitchen tablespoons[2].

Change the chemical group of the product from one spray to the next. Make a tank mix only of products that the labels let you mix. Add the products in the sequence that the labels give.

Do not spray in these conditions: high light intensity, hot and dry air, or drought stress. A spray causes more damage to leaves that have stress.

Coverage sequence: media to leaf top11 Media topsoak thesubstratesurface→22 Up the stalkstalk and bottomstems→33 Leaf bottomswhere pests stay→44 Leaf topscomplete thecanopy
Figure 9. Good coverage is very important. Use a fan tip and a different sprayer for each product. Thus there is no cross-contamination.
Example of a spray rotation for one week. The table gives types of products and does not give brand names. Sulfur* is for mother plants and for the vegetative stage only, a maximum of one time in 2 weeks. Always read the label for the REI and the withholding period.
DayProduct or tank mixTargetREIWithholding period
MondayApproved foliar solutionGeneral hygieneAs on the labelAs on the label
WednesdayApproved foliar solution + sulfur*Powdery mildew, mitesAs on the labelAs on the label
FridayBiocontrol: release predatorsMites and thripsNoneNone
When necessaryApproved curative product (change the chemical group)Active outbreakAs on the labelAs on the label
Figure 10.
Spray when the media is saturated

Spray when the media is at full saturation. At this time, a spray decreases the foliar uptake and the risk of leaf burn[2]. Spray at the change in the irrigation, when the substrate is wettest.

Foliar spray and root drenchthe effect of the product is different in each arealiquid on the leavesFoliar spraytouches the leaves, fast, butthe effect is shortRoot drenchin the medium, roots absorbit. Systemic, longer effect
Diagram. A foliar spray touches the leaves and is fast. A root drench is systemic and continues for a longer time. The effect is different because the treatment goes to a different area.
Protection

Sanitation and quarantine

Most pests move into the room with persons. Thus the easiest control is to stop the pests before they go into the room. Shoes are the primary item that moves pests into the room[1].

Before you go into a grow room, change your shoes or put on overboots. Clean your hands when you go in and after each work break. Keep nitrile gloves on your hands at all times. Replace the gloves after each work break and after you touch chemicals. If you are not sure, replace the gloves.

Each new plant that comes into the facility goes to quarantine. On the day that you receive the plant, clean it with an approved foliar solution. You can also put the plant in the solution. Then keep the plant in a quarantine tent, isolated from the crop, for a minimum of 2 weeks. Monitor the plant during this time, before you move it to the crop[1].

Think that all plant waste is dangerous material. Put the waste in a bag in the room. Weigh the waste and record the weight. Then move the bag directly to the green waste.

Use the equipment for one room only. Clean the equipment after each task. Thus a tool does not move pests from one room to a different room.

Steps to go into the room, each time1Change shoesoverboots orshoes for theroom→2Clean handswhen you go in→3Put on glovesnitrile, always→4Foot bathgo through it→5Go in and outnew gloves whenyou go out
Figure 11. Shoes are the primary item that moves pests into the room. Use the sequence each time that you go in. Do the steps in the opposite sequence when you go out.
Quarantine of a new plantClean it when you receive it. Monitor it for 2 weeks or more. Move it to the crop only if it stays clean.00122day 0: clean itday 7day 14to the cropin quarantine
Figure 12. Keep new plants isolated for a minimum of two weeks and monitor them. Only a plant that stays clean can go to the crop.
Do not use a tool in more than one room

Keep scissors, buckets, sprayers and PPE in one room only. Clean these items after each task. A tool that you use in more than one room can move pests from one room to a different room.

Step by step

IPM tasks for each day, decision flow and records

Use the sections before this section to make one procedure. Do the procedure again in each shift. The loop for each day is short. The decision flow gives the treatment for each finding.

  1. 1
    Prepare and go into the room
    Change your shoes. Clean your hands. Put on gloves. Go through the foot bath.
  2. 2
    Scout in the same sequence
    Examine the substrate, the stems, the bottom side of the leaves and the top side of the leaves. Use the same sequence each day.
  3. 3
    Read the traps and write the date
    Count the insects on each sticky trap. Write the date of the check on the trap. Record the trend.
  4. 4
    Record each finding
    Record the name of each pest and the damage. We recommend that you add photos to the record each week.
  5. 5
    Use the decision flow
    Identify the pest. Compare the quantity of pests with the threshold. Select one treatment: monitor, biocontrol, spray, or remove and destroy. Use the growth stage and how large the problem is to select the treatment.
  6. 6
    Record, then scout again
    Record each treatment. Then compare the trap counts before and after the treatment. Make sure that the treatment gave a good result.
The primary decision flow (from a finding)1Identifyfind the pest ordisease name→2Less than threshold?monitor, scoutagain→3First sign?scout, exclusionand biocontrol→4>3% and in window?approved spray→5Large after window?remove, destroy→6Record, scout againexamine result
Figure 13. Use this sequence for each finding. The growth stage and how large the problem is select the next step. The loop always ends with a record. Then you scout again.
Template of a pesticide log, with no entries. You must record each spray in the log. The manager must write a signature on the log.
ItemInformation to record
DateDay of the spray
ProductName on the approved list
Active ingredientThe name of the active chemical
DilutionRate on the label
Area or roomThe area where you applied the product
ApplicatorThe person who sprayed
REIThe REI, shown on the door
Withholding periodThe time before you can harvest
Signature of the managerApproval on the log
Figure 14.
Records are also a feedback loop

Put a notice of the REI on the door of the room. Remove the notice only after the interval ends. Make an entry on the calendar of the room during the spray and after the spray[6]. Good records also show that a treatment gave a good result. Compare the numbers of insects on the traps before and after the treatment.

Problems and results

Troubleshooting and usual results

The frequent errors are always the same. You do not scout until you see damage. You spray a pest that you did not identify. You ignore the treatment window and spray in the last stage of flowering. You use the same tools or PPE in different rooms. You let predators go into the irrigation system.

Each error has a short correction. Most errors occur because personnel do not obey the procedure. Equipment is not the cause.
Frequent errorCorrect procedure
Scout only when damage showsScout in the same sequence at each check, before damage shows
Spray a pest that you did not identifyUse a loupe to identify the pest. Then select a treatment.
Spray in the last stage of floweringUse the treatment window. After day 21, remove and destroy plants with a large infestation.
Use the same tools and PPE in different roomsUse equipment and gloves for one room only, and clean them
Biocontrol media in the irrigation systemHang sachets or release boxes
Airborne fumigators in floweringDo not use them. They move into the buds.
Metal hose clamps in sprayersUse fittings that are not metal. Rust causes an unsatisfactory result in the test for heavy metals.
Figure 15.

Do not use airborne fumigators in a flowering facility. They can move into the buds and cause damage to the crop[2]. Examine the sprayers for corrosion of the parts that touch the product and of the fertigation parts. This corrosion can cause metals contamination in some conditions[1].

Work to prevent pests is much less than work after an outbreakWork and cost, compared. Stable work to prevent pests is much better than work after an outbreak.025507510025 effortPrevent pests (scout, hygiene, predators)90 effortWork after an outbreak
Figure 16. After a long time of operation, the work in an IPM system is mostly stable work to prevent pests. A curative spray is not frequent.
Usual results

IPM does not give a room with no pests at all times. With IPM, you find pests when the problem is small. You keep the pest populations less than the threshold. You do not let a problem continue to the harvest.

After a long time of operation, the work in an IPM system is mostly preventative. You scout each week. You monitor the trends of the sticky traps. You use the clean procedure to go into the room. You apply a weak preventative foliar spray. A curative treatment is not frequent.

Make the regular procedure first. Then most of the emergency treatments are not necessary. Use this SOP with the mold risk guide for disease pressure and with the airflow design guide. Clean air that moves is one of the best controls for pests.

Related papers
Mold risk
Find and stop bud rot
Airflow and fans
How much air to move, and where to put the fans
Harvest, dry, trim, cure
All the steps after harvest

References

  1. Punja, Z. K. (2021). Emerging diseases of Cannabis sativa and sustainable management. Pest Management Science, 77(9), 3857-3870. https://doi.org/10.1002/ps.6307
  2. Scott, C., & Punja, Z. K. (2021). Evaluation of disease management approaches for powdery mildew on Cannabis sativa L. (marijuana) plants. Canadian Journal of Plant Pathology, 43(3), 394-412. https://doi.org/10.1080/07060661.2020.1836026
  3. Elmoghazy, M. M. E., Elsherbini, D. M. A., Mashlawi, A. M., Ibrahim, A. M., El-Mansi, A. A., & El-Sherbiny, M. (2024). Implications of temperature and prey density on predatory mite Amblyseius swirskii (Acari: Phytoseiidae) functional responses. Insects, 15(6), 444. https://doi.org/10.3390/insects15060444
  4. Mumtaz, M., Rahman, V. J., Saba, T., et al. (2023). Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) at different temperatures. PeerJ, 11, e16461. https://doi.org/10.7717/peerj.16461
  5. Koppert Biological Systems. Phytoseiulus persimilis - Predatory Mite for Spider Mite Control (technical/product sheet). (source not from a journal, for example from a manufacturer) https://www.koppert.com/crop-protection/biological-pest-control/predatory-mites/phytoseiulus-persimilis/
  6. U.S. Environmental Protection Agency. Notice to Workers About Pesticide Applications and Pesticide-Treated Areas (Worker Protection Standard). (source not from a journal, for example from a manufacturer) https://www.epa.gov/pesticide-worker-safety/notice-workers-about-pesticide-applications-and-pesticide-treated-areas
  7. New Zealand Ministry of Health. Pesticide use during cultivation of medicinal cannabis. Guidance under the Misuse of Drugs (Medicinal Cannabis) Regulations 2019; updated guidance effective from July 2024. (source not from a journal, for example from a manufacturer) https://www.health.govt.nz/regulation-legislation/medicinal-cannabis/information-for-industry/pesticide-use-during-cultivation

Each citation in the paper, for example [1], refers to an item in this list. Each item is a primary source or an instruction from an authority, unless the item shows a different type. The results of cannabis tissue culture change much with the genotype. Before you use the dilutions, hormone doses and local regulations, make sure that they agree with the primary sources.