Integrated Pest Management for Cannabis
Integrated pest management for cannabis is a routine, not a bottle. You pick a day, walk the plants, name what is actually there, and change the condition that let it in. A spray is the last move, and it stays in veg, while the plant is still only leaves.
Crops get wrecked by a mismatch. Ladybugs dumped on spider mites. Oil wiped over flowers that are already stacking. A yellow card left up so long the insects on it could have arrived last month. The way through is an order you can repeat. Keep the pest from walking in. Identify it with a loupe. Write the count. Fix air and water for that pest. Match a hunter to the name you wrote. Use a contact spray only while the plant is vegetative and the label fits the job. A week later, look again.
You are keeping damage small enough that the flowers still finish. One fungus gnat on a fresh card can wait. Webbing on a cola means you are late. Pale specks on a leaf are early. The same walk covers marijuana in a tent and a backyard weed garden. In much of Canada the home cap is four plants, and Quebec and Manitoba are tighter. The cap does not scout for you.
Integrated Pest Management Is a Routine
Veg can live with one pass a week. Flower, and any hot week, needs a second look. Spider mites speed up in warm, dry air. Mildew and bud rot speed up when flowers stay wet. You will not see either from the doorway.
Start at the door plant. Check the newest tips, where aphids and thrips settle. Flip two fan leaves on each marked plant. Glance at the soil for flies and algae, then read the cards. Write three numbers before you throw a card away: stipple or moving specks on the leaves you always check, insects on the canopy card, and insects on the soil card. A climb from last week is the trigger. A flat line means the bottle stays put. Your notes are the threshold. There is no universal count that fits every tent.
- Check the same three plants: door, middle, and back wall.
- Flip two leaves on each and use a loupe.
- Read both cards, write the counts, then replace the cards.
- Change one thing only if those numbers climbed.
Not a Bottle You Spray on Buds
Keep the plan on the calendar and the jug on the shelf until the calendar says veg and the loupe has a name. The jug is one labeled contact spray for a pest you already identified. It has a printed rate. It also has a stop date, and that date is the arrival of open flowers.
Oil, soap, and neem on a cola sit in the resin. You taste that later, in the jar. Oil also holds moisture inside a tight flower, and a cola that was clean can go soft and brown from the inside because it never dried. Scissors, a yellow card, moving the worst plant out, and a predator that matches the pest are the flower tools. The sprayer had its turn in veg.
Prevention Before the Count Climbs
Most infestations ride in on scissors, a garden jacket, dead leaves left on the mix, or runoff sitting under the pots. Clean the floor before you flip. Wipe scissors with alcohol between plants, and keep a separate pair for outdoor work. Leave the garden clothes at the door. Pull trash out of the pots. Algae on a rim and a cloud of gnats show up together.
Air should make the leaves tremble across the whole canopy. A fan parked on one cola burns that cola and leaves the back corner still. If plants touch on every leaf, split them so you can see an underside. The stale corner is the first place you look.
Name the Pest
Green aphids on a stem are pear-shaped, they cluster on soft growth, and they leave honeydew that feels like syrup. Dust sticks to it. That is aphids, and the aphid guide stays with that insect. Aphids, spider mites, thrips, fungus gnats, whiteflies, and caterpillars do not share a cure. A mite product will not dry a soggy pot. Bt leaves aphids alone and leaves grasshoppers alone. Holes plus a hopper is a grasshopper job.
A hungry leaf goes evenly pale in a patch or along the edge. Spider-mite stipple is fine dots on a leaf that stays green between them, and the dots multiply. Honeydew shines. Mite damage does not feel sticky. Movement under a 10x to 30x loupe means an animal. Even yellow with nothing moving means feed, pH, or light, not the spray shelf.
Undersides and a Loupe
Flip the leaf. Mites and many eggs sit underneath, and the first mark on top is that sanded stipple. Webs mean the colony is already large. Rest a loupe on the leaf and watch. A white sheet and a tap still works. The spider mite guide shows how to separate a moving speck from dust. Thrips leave silver streaks and tiny black specks. Whiteflies lift in a cloud when you bump the stem.
Broad mites and russet mites twist new growth until it looks strapped or glossy, and a normal two-spotted mite may not be in sight. Get a closer look before you drench the tent. If one plant is already webbed, bag it before you walk it past the others. Wash up, then check the neighbors the same day.
Sticky Cards and a Written Count
A yellow card tells you something is flying. It does not end the infestation, and it does not dry the soil. Hang one just under the top leaves for thrips, whiteflies, and winged aphids. Hang a second a little above the mix for fungus gnats. A card on the ceiling misses the canopy. A card stuck to a wet stem becomes trash.
Change the card on scout day. Count, write, replace. A card that has hung for three weeks cannot tell this week from last month. A few insects on a fresh card can be a quiet room. A card that fills before the next walk is a climb. The thrips and fungus gnat guide goes further on placement and on the soil predators that belong with gnats. If the soil card is the one rising, fix the watering.
The Same Plants Each Week
Pick three plants and stay with them. The one by the door, one in the middle, one against the back wall. A blank stake is enough to mark the set. Check those three every walk, then take a slower lap so a new hotspot does not hide outside the routine.
The cheat is always the plant in the best light. The corner plant is where still air keeps a colony. Write the ugly leaf. “Back plant, silver streaks on the new fan, canopy card up, soil card flat.” That sentence beats a note that says the room seems fine.
Stop the Easy Way In
Pests ride in on something you carried. A cut from a friend. A plant that spent a week on the porch. Mix that lived in a shed with houseplants. Scissors that did outdoor work and indoor work on the same day. The plant outside the tent is in the right place. It is not in the room yet.
Do not set a newcomer inside the flower tent just to look. If you only have one tent, inspect in another room and keep those scissors away from plants already in flower. Wash up before you go back in.
Quarantine Clones and Cuts
A seed is the cleaner start. A seed does not import spider mites the way a rooted cut does. Clones need a longer hold than a pack you germinate yourself. Give the new plant its own shelf, its own card, and its own scissors. About two weeks is a fair hold if you actually look: undersides on day one, again a few days later, and again the day you decide it can join the others.
Day one covers tips, undersides, the soil surface, and the cut stem. A clean top with mites on the third leaf down is still a fail. Honeydew on the stake is a fail. Flies on the little card by day three are a fail. The intake guide goes further on clones and seeds. Do not shrink the hold because an empty pocket in the tent is bothering you. One mite on a cut becomes webbing after the flip, the same week you lose the option to oil anything.
Air, Water, and the Pest You Invite
One climate will not shut off every pest. Spider mites do well hot, dry, and dusty. Fungus gnats do well when the top of the mix never dries. Powdery mildew likes mild air that barely moves. Bud rot likes a dense flower that stayed wet. Change the condition that matches the pest you named. Chasing a humidity that “ends mites” is how a flowering room gets mildew.
Water the pots, then let the surface dry before you water again. Skip foliar feeds once flowers are forming. A leaf that is still wet when the lights go out is a head start for mildew. The fan has to move every corner, including the one that is awkward to reach. Build this in veg. After flowers stack, you are stuck with the airflow you already have. The veg stage notes cover plants growing into each other. The flower stage notes cover the weeks when the cola is what you are protecting.
The Hunter Has to Match
A ladybug on a fan leaf beside the flowers can stay. She is there for aphids. Leave the oil capped. Ladybugs, lacewing larvae, and the wasp Aphidius are the aphid crew. Spider mites need predatory mites. A tub of ladybugs on a mite outbreak looks like action and leaves the mites feeding. The beneficial insect guide lines the hunters up by pest. Read it before you order a mixed cup and hope they sort themselves out.
Release in the evening, onto dry leaves, at the spot where you saw the pest. Follow the rate on the supplier card that came with the insects. That card knows the product. This page does not know the size of your tent. If the instructions say to keep them cool on the way home, a hot car all afternoon is why nothing hatches.
Spider Mites and Thrips
Two-spotted spider mites are the moving specks and the stipple. Phytoseiulus persimilis is the predatory mite for an outbreak. Neoseiulus californicus is the one that holds a low population and copes a little better in a warmer, drier tent. Release while the count is small. On cannabis they often fail to breed the way they do on a pepper leaf, so if the stipple is still spreading a week later, release them again. Heat and very dry air favor the pest. Ease that if you can do it without wetting flowers. You will not find a humidity that ends mites and also keeps mildew away.
Thrips are the silver streaks and the black specks. Amblyseius cucumeris or Amblyseius swirskii take larvae on the leaf. Pupae drop into the mix, so a soil mite such as Stratiolaelaps, often sold as Hypoaspis, covers that step. Orius can take adults when a supplier has them. A quieter card with fresh silver on the new leaf means the larvae are still feeding.
Aphids, Whiteflies, and Caterpillars
Aphids cluster and leak honeydew. Ladybugs and lacewing larvae eat them. Aphidius leaves a tan mummy where it laid into an aphid, and those mummies mean the wasp is working. On a small veg plant, wipe a cluster with a wet finger, then release the hunter so the rest do not rebuild on the tips.
Whiteflies get yellow cards and, in veg, a contact soap. Encarsia is the wasp used where a supplier carries it. Ladybugs bought for aphids will not clear a whitefly cloud. Caterpillars leave holes and dark droppings. Bt, Bacillus thuringiensis, works while they are small and still outside the bud. It does not touch mites, aphids, or grasshoppers. A caterpillar already inside a cola has to be cut out.
Fungus Gnats in the Mix
Adults are the small flies on the soil card and on the wet mix. Larvae sit in the top layer and rasp roots, which leaves the plant cranky for a reason you cannot see from the tops. Water thoroughly, then wait until the surface is dry. A sip every day keeps the larvae happy. Steinernema feltiae is a nematode you water in for those larvae. Cards show the trend. They do not replace the dry-back.
Yellow leaves plus flies are not automatically gnats killing the plant. Check the roots before you drown the pot. If the plant wilts and the root ball shows white waxy specks, think root aphids. That insect lives on the root. A gnat nematode will not be the whole answer. Name it, then deal with the root zone on purpose.
Do Not Oil the Hunters
Oil, sulfur, and a broad insect fungus such as Beauveria kill the hunters you just paid for. Keep spray day and release day apart. Stacking three products in one afternoon is not a program. If the leaf is still oily, predatory mites released that evening are walking onto a trap.
Let the leaf dry and wait out the interval printed on that label before you release. There is no single gap that is safe for every jug. If the label never mentions beneficial insects, treat the spray as hostile to them. The green lacewing you notice on a leaf is usually the adult. The larvae do most of the aphid eating, and they look like tiny segmented alligators, not like the winged adult. People flick the adults off because they do not recognize the help. Either form dies under a coat of oil.
Sprays Have a Stop Date
Contact sprays expire as a tactic when real flowers start. A pump sprayer belongs beside a plant that still has only leaves. Early veg is the useful week, when you can coat an underside, let it dry, and still have time ahead. The night before you flip is a worse week. Any day after white hairs show is the wrong week.
Write the stop next to the counts. “Last soap pass, end of veg.” If that line is missing and the plants are hairy, you are past it. The cola looks valuable, the mites are obvious, and the bottle is in your hand. That is the moment the routine is for. Put the bottle down. Cut the worst leaf. Order the predator that matches.
Contact Sprays in Veg
Soap and horticultural oil kill by touching the insect. Spray with the lamps low, coat the underside and the petiole, and let the leaf dry before strong light returns. Droplets under a hot lamp burn tissue. One thorough pass beats three light mists. Use one labeled product at the printed rate. Skip the kitchen mix, and do not combine soap, oil, and neem in one tank.
Neem stays in that veg drawer. Strong light burns a wet leaf, and open outdoor blooms plus neem are rough on bees. The neem guide covers those limits. Spinosad is a label question. If the bottle lists cannabis where you live, follow it. If cannabis is not listed, do not invent a dose. This page is not a Canadian product registry. Scout a week later and repeat only that same product, after the interval on its label.
Nothing Oily on Open Flowers
A frosty cola is why the sprayer stopped. Open flowers do not get oil, soap, or neem. A light mist counts. So does “only the sugar leaves.” Residue in the resin is part of what you taste when you smoke the marijuana, and oil inside a dense flower is trapped water. Flower work is scissors, a lower leaf you can spare, moving a hot plant out, cards, and a predator that still matches the pest.
The spider mite page says the same thing once flowers are up: hunters and scissors. Webbing late in flower does not unlock a new chemical. Cut the worst leaf into a bag, release the right predatory mite if you can still get it, and wash your hands before the next cola. If several plants are webbed and harvest is close, you are managing a finish. Keep tools clean. A foliar will not rewind the month.
Check Whether It Worked
A week later, read the same three plants and the same two card positions. You want the count lower, or at least flat. Some yellow fan leaves in a flowering canopy are old leaves finishing. They are not a new pest by themselves. Look for the insect, the stipple, the silver streak, or the honeydew. If those are down and the fan is simply old, leave the fan.
Write one line. “Persimilis released Tuesday. Canopy card lower. Stipple on the door plant unchanged.” A note that only says “treated plants” is useless in October. A good week is boring: the numbers fell or held, and you added nothing new. A bad week is also simple. The numbers rose, so you pick one cause.
A Count That Kept Climbing
A climb has a short list of causes. The name was wrong, so the hunter was wrong. The spray never reached the underside, so the insects you missed rebuilt. Or the spray killed the hunters and the pest had the leaf to itself. Change one of those. Two new products in the same afternoon means next week cannot tell you which move mattered.
Read where the climb happened. Canopy card up, soil card flat, stipple spreading: mites or thrips. Soil card up, canopy quiet, leaves unmarked: watering and gnats. Honeydew and clusters: aphids, even if the card also caught a few flies. A crowded card in a flowering tent is a late note. It sends you back to the name, the room, and the hunter. If the underside is still full of moving specks after a spray and you are still in veg, turn the leaf over and cover it. In flower, the redo is scissors and predators.
Mildew Is a Different Job
Powdery mildew and bud rot are separate from the insects above. Mildew looks like flour on the top of the leaf and likes still, mild air. It smears if you wipe it. A water spot usually does not. Bud rot, Botrytis, is brown mush inside a cola. The outside can look fine until you open it. A mite spray fixes neither one. Cut brown tissue out with a margin of clean flower, and wipe the scissors before the next cola.
The powdery mildew guide is the leaf disease. Outdoor plants also pick up fungi and chewing insects from weather. The outdoor fungi and pest piece is the one for a garden in the weather. Sulfur, where a label allows it for mildew, is rough on predatory mites. If hunters are already on a mite job, do not dust sulfur over them.
Then stop adding products. Name the pest. Take away the condition it likes. Match the hunter and use the rate that came with it. Spray only in veg, by contact, at the label rate, and stop when flowers stack. Look again on the same plants and write one line.
Integrated pest management for cannabis is that loop. A weed garden that gets a weekly walk stays ahead of the room that gets a panicked bottle on Friday night. Tomorrow, start with the door plant. Flip two leaves. Read the card. That is the program.
