Pests, Bugs & Viruses

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by Nebula Haze

Unfortunately, bugs and other garden pests can totally mess up your marijuana harvest!

This page aims to be a comprehensive resource on the different types of bugs / pests / mold that can affect your marijuana crop, along with tips for preventing and solving each problem.

Pests that can affect your marijuana plants include aphids, fungus gnats, thrips, green flies, black flies, mosaic virus, spider mites, caterpillars, inchworms, whiteflies, white powdery mildew / white powdery mold, stem rot, and even mammals such as deer or cats!

  • Aphids
  • Barnacles / Scale Insects
  • Broad Mites & Russet Mites
  • Bud Rot or Mold
  • Caterpillars & Inchworms
  • Crickets
  • Fungus Gnats
  • Grasshoppers
  • Leafhoppers
  • Leaf Miners
  • Leaf Septoria / Yellow Leaf Spot
  • Mealybugs
  • Root Rot
  • Slugs / Snails
  • Spider Mites
  • Thrips
  • Tobacco Mosaic Virus (TMV)
  • Whiteflies / White fly
  • White Powdery Mold

It’s time to fight back against cannabis bugs, mold and pests!

Quick Tip! Whenever you spray plants with anything, make sure to get the undersides of the leaves too, as this is where many pests like to hang out! A one-hand pressure sprayer / mister is also really helpful for spraying leaves.

Pests, Bugs & Viruses


Aphids
Aphids live under leaves & have different forms depending on their stage of life

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Barnacles / Scale Insects
These bugs that look like barnacles and stick to the plant on stems and underneath leaves

Pests, Bugs & Viruses

Broad Mites or Russet Mites
These mites are so small you will likely never see them even under a magnifier. However, you can tell your plant has been infected because your new leaves will be blistered, twisted and glossy. The overall plant will also be growing poorly and if it’s flowering the buds may turn brown. Broad mites and russet mites are often mistaken for other problems like nutrient deficiencies, heat stress or pH problems.

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Pests, Bugs & Viruses

Bud Rot or Mold
When bud rot strikes, certain buds may start looking sickly overnight, with leaves turning yellow and/or bud becoming discolored. When opened up the inside of the bud is dead or moldy.

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Caterpillars, Inchworms & Cabbage Loopers
Caterpillars and worms eat holes in leaves and leave droppings that look like black specks

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Crickets
“Regular” crickets will munch on your leaves while “mole crickets” can tunnel under your plants and disturb their roots!

“Regular” Crickets

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Mole Cricket – these can tunnel under your cannabis plants like moles

Pests, Bugs & Viruses

Fungus Gnats
Fungus gnats look like tiny dark flies. They hang around soil that stays wet for long periods of time, and their worm-like larvae crawl around in the wet top soil. Plants start getting sick if a gnat infestation gets out of control.

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Grasshoppers
You’ve probably seen these before, but these seemingly harmless garden creatures will happily eat your cannabis leaves!

Pests, Bugs & Viruses

Leafhoppers
These bugs come in almost every color known to man so sometimes it can be tough to tell what they are just from looking. However, they all make clusters of spots on your leaves where they’ve sucked out all the sap, so if you see spots like this you know you’ve got leafhoppers!

Pests, Bugs & Viruses

Leaf Miners
Leaf miners are larva that actually live inside your leaves and tunnel through them to eat!

Pests, Bugs & Viruses

Leaf Septoria / Yellow Leaf Spot
This fungus causes round yellow or brown spots, with symptoms often starting on lower parts of the plant

Pests, Bugs & Viruses

Mealybugs
These tiny white bugs look “hairy” and are found crawling on leaves and buds

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Root Rot
Root rot is a common problem in hydroponic systems though overwatered plants in containers often display similar symptoms. Plants with root rot wilt and leaves may become discolored. In the reservoir the roots turn brown, smelly and slimy.

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Pests, Bugs & Viruses

Pests, Bugs & Viruses

Slugs / Snails
Slugs and snails usually come out at night, leaving holes in leaves which have scalloped edges from their individual bite marks. They also leave slime trails on leaves and on the ground.

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Spider Mites
Spider mites are often caught from another grow room, and their bites leave small white speckles all over your leaves. They’re so small they can be hard to see, though the best place to look is underneath leaves. You may see webbing if there’s enough of them living on the plant.

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Thrips
Thrips leave irregular bronze or silver marks that may look like “dried spit” or tiny snail trails. Their young look like fat, tiny worms.

Pests, Bugs & Viruses

Pests, Bugs & Viruses

Tobacco Mosaic Virus
It’s not known whether mosaic virus has jumped from tobacco to cannabis plants, but in this article I’ll share what I’ve learned so far…

Pests, Bugs & Viruses

Whiteflies/ White fly
Whiteflies look like tiny white moths and hang out under your cannabis leaves

Pests, Bugs & Viruses

Pests, Bugs & Viruses

White Powdery Mold
WPM leaves a white powdery substance that looks like flour or powder on leaves and stems

Pests, Bugs & Viruses


Don’t see your bug here? Send us a pic!

 


 

Jump to…

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Leaf Color

  • Black or Gray Patches on Leaves
  • Brown or Dark Spots
  • Dark or Purple Leaves
  • Edges Appear Brown or Burnt
  • Mottling / Mosaic Pattern
  • Pale Color Leaves
  • Veins of Leaves Stay Green
  • Yellow Leaves – Lower, older leaves
  • Yellow Leaves – New Growth
  • Yellowing Between Veins

Leaf Symptoms

  • Abnormal Growth
  • Leaf Edges Appear Burnt
  • Leaf Tips Appear Burnt
  • Leaf Tips Die
  • Leaves Curl Under
  • Leaves Curl Upwards
  • Lower Leaves / Older Growth Affected
  • Mottling / Mosaic
  • Old Leaves Dropping Off
  • Red Stems
  • Slow Growth
  • Spots
  • Twisted Growth
  • Upper Leaves / Newer Growth Affected
  • Webbing on leaves
  • Wilting / Drooping
  • Yellowing Between Veins
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Other Symptoms

  • Buds Not Fattening
  • Bugs
  • Webbing

Plant Symptoms

  • Leaves Curl Under
  • Leaves Curl Upwards
  • Old Leaves Dropping Off
  • Plant Wilting / Drooping
  • Red or Purple Stems
  • Slow Growth
  • Twisted Growth
  • Weak Stems

Root Symptoms

  • Slow Growing

 

 

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