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Thrips

What Does Cannabis Thrip Damage Look Like?

Adult thrips are small, fast-moving insects, while young thrips look like tiny unmoving pale worms on the leaves. In fact, thrips can come in many forms, from wormy nymphs to dark or golden winged insects, depending on the stage of life and where you live.

They pierce cannabis leaves with their mouths and suck out all the good stuff, leaving shiny (sometimes people think it looks slimy), silver or bronze spots wherever the leaves were bitten. The spots are bigger and more irregularly shaped than the bites left from spider mites. If it goes on too long the affected leaves may start dying.

Examples of thrips damage on marijuana leaves (irregular silver or bronze spots)

Although it doesn’t really look like it in pictures, in real life thrip damage has been described as looking like “dried spit” or tiny snail trails.

(thrip leaf damage pics by theMallacht)

Here’s a picture of an adult thrip on a finger for scale – they’re tiny!

They can appear dark colored like the ones above, but also yellow, transparent or golden

They can appear with or without wings, depending on their stage of life

In their “nymph” (juvenile) form, thrips appear pale, fat and almost wormy from afar

A closeup of another baby thrip in “nymph” form

A Thrip nymph on a cannabis leaf – I hope this helps show you how tiny they are.

A thrip nymph looks tubular and worm-like, unlike an aphid nymph which looks like a tiny white bug

Proven Thrip Remedies

1.) Insecticidal soap

Fatty acid salts or insecticidal soaps can be a good choice against thrips. They weaken the outer shell of thrips but are safe to use on your plants and they don’t leave much of a residue.

With soaps, coverage is very important as it does not stay on your plant for long, so follow-up applications may be necessary. Although this is considered safe, avoid getting any on your buds!

2.) Neem Oil

Neem Oil will leave an unpleasant taste/smell on buds when used to treat flowering plants, so don’t let this stuff get near your buds! There’s also some evidence Neem oil may be harmful to humans so use with care! That being said, Neem oil is an all-natural remedy that is very effective against many different types of bugs and mold. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly since neem oil and water can separate easily.

3.) Spinosad Products

Spinosad products are organic and unlike many other thrip pesticides, completely harmless to pets, children, and plants. Unlike many insecticides, you can spray spinosad heavily on leaves and roots with basically no negative effects. Spinosad products can be used directly to kill thrips on contact, but can also be used when watering plants to systematically kill thrips via the roots. Spinosad is also effective at fighting caterpillers, spider mites, and many other marijuana pests.

Can be used both as a topical spray, and can also be used directly at the roots. Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria (actinomycete Saccharopolyspora spinosa) and kills thrips via ingestion or contact by affecting the insect nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to thrips, but is less toxic to many beneficial insects.

Note: Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. Anything left over will be waste.

4.) Pyrethrins

Pyrethrin based insecticides are not very toxic for humans and degrade quickly, which is why they’re commonly recommended for vegetable gardens. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

Pyrethrin products break down quickly, over the course of just a day or two. The major problem with them is they are very toxic to bees. Although cannabis plants generally don’t attract a lot of bees, please use this as a last resort, and also try to use it right after the sun goes down because bees sleep at night. This lets it start to break down before they wake up.

Use pyrethrin products when the sun goes down! Save the bees!

A popular example is Bonide 857 Pyrethrin Spray Concentrate. Use 3 tablespoons of concentrate per gallon of water.

Plant Symptoms

  • Bronze or brown patches
  • Brown or slimy roots
  • Brown or yellow leaf tips/edges
  • Buds dying
  • Buds look odd
  • Bugs are visible
  • Curling or clawing leaves
  • Dark leaves
  • Drooping plant
  • Holes in leaves
  • Mold or powder
  • Pink or purple on leaves
  • Red stems
  • Shiny or smooth leaves
  • Spots or markings
  • Twisted growth
  • Webbing
  • Wilting leaves
  • Yellow between leaf veins
  • Yellow leaves

This page is part of our Plant Doctor series. You can use our tool to filter by symptom and help diagnose your plant.

If you see tiny, wormy little bugs, dark winged insects or bronzed discoloration on the leaves, you may have thrips. Learn how to get rid of them!

How to Get Rid of Thrips on cannabis Plants

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  • Escrito por : Ciara
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Finding out that your plants have been infested is one of the worst feelings, and sometimes figuring out how to get rid of thrips on cannabis plants can be complicated, depending on the stage they’re in. In this post, we’re going to talk about how to prevent, identify and eradicate one of the most common pests when it comes to growing cannabis and gardening in general; thrips.

Thrip Prevention

Before you’re unlucky enough to find out what thrips look like, you should already be working on preventive measures to ensure that you never have to actually see one. In order to avoid thrips from thriving on your plants, you need to make sure that they’re as healthy as possible. In order to do this you’ll need to help them to strengthen their own natural defenses. You can also use preventive products; if possible, we recommend using penetrant products that actually get into , making it hard for insects to stay on your plants and procreate; thrips feed off of sap.

  1. Use plant fortifying products.
  2. Spray penetrant preventive products.
  3. Use solid penetrant preventive products in the substrate.
  4. Place various insect traps.
  5. Cover the surface of your substrate in plastic.
  6. Use high quality substrate.
  7. Do not add new plants or clones from other grows to your growing area.
  8. Disinfect and sterilize your growing room/area and material before you start.
  9. Avoid high temperatures and over-soaking substrate (indoor growing).

In order to prevent thrips from taking over your plants we highly recommend using preventive products both via foliar application and in the substrate; one of the processes that these insects go through before they become adults happens in soil. Another important factor is the temperature, just like with almost every other insect infestation; we highly recommend keeping the air/substrate temperature under 25ºC. You should also refrain from bringing other plants or clones into your growing area without having disinfected them and kept them in a type of quarantine afterwards to make sure they aren’t carrying anything.

How to Detect Thrips

One of the most common ways of identifying and thrip infestation is by the small marks that they leave behind on leaves, which are incredibly similar to those left by the white fly. However, you’ll also be able to distinguish small shiny marks and black spots, which are the feces of the thrips. Thrips contain toxic substances in their saliva that can cause deformations on certain parts of the plant, especially on the leaves, which is a good indicator that you have a thrip infestation.

In as far as the actual insect, they can measure anywhere from 0.3 to 14mm long, and they look different depending on the stage that they’re in, which is why there are light green, white, gray and brown thrips – some are even entirely black, with or without leaves.

Thrip Life Cycle

What Damage Can a Thrip Infestation Do?

Thrips are known for laying their eggs within the small layers on plant leaves, so that when they hatch they cause a very small hole through which all types of bacteria and fungi can get through. Once it hatches, it starts to feed off of the plant’s sap, producing the small marks and deformations we mentioned earlier.

Plants that are deeply infected become much weaker and stop growing properly; in a few cases they might even die out completely, especially younger plants. Adult plants that die after being infected by thrips usually end up catching some sort of illness or fungi that managed to make its way through the little holes left by the insects on the leaves.

How to Get Rid of Thrips on Cannabis Plants

In order to talk about how to efficiently get rid of thrips on cannabis plants we’re going to go over a few different products that be used to treat this particular infestation as well as others. Keep in mind, however, that thrips start off by thriving on the leaves, then they move to the substrate in order to finish their metamorphosis into adult plants, who then go back up to the top in order to reproduce. This means that you need to treat the substrate and the upper layers of the plant in order to get rid of the thrips as fast and as efficiently as possible, as this infestation is capable of reproducing and taking over your plants in no time at all.

How to Get Rid of Thrips: Insecticides

Neem Cake

Neem cake, apart from containing certain nutrients, is capable of improving the actual structure of your soil and improving plant growth. It’s also incredibly efficient when it comes to getting rid of insects in the soil, although it’s even more efficient when sprayed. This product is organic and penetrant; your plants absorb it and keeps it inside for a while. It essentially causes certain types of insects to stop reproducing, so they either leave or dye off.

Soilnabis

Soilnabis is quite the complete product, made using vegetal extracts, and it’s capable of stimulating all types of plant growth while also increasing your plants’ natural defenses, stopping insects from reproducing in the soil thanks to its Alpha-terthienyl, which is toxic for larvae and insects.

Cythrin Garden

This product allows you to get rid of some of the most common insect infestations when it comes to growing cannabis, including thrips. This product acts as soon as it comes into contact with the insect, creating an intense repellant effect; it can be used either as a preventive measure or to get rid of insect infestations.

Sticky Fly Traps

A lot of growers use blue and yellow fly traps when it comes to both indoor and outdoor growing; for thrips, we highly recommend using blue traps, although you should be using both anyway so that you can catch a more varying type of insects that might want to get near your plants.

Orius Laevigatus

When it comes to thrips sometimes the best option is to fight fire with fire; these insects are predators and they’re one of the most recommended methods of fighting them off without needing to use any products; it’s a great way to easily and viciously get rid of all thrips on your cannabis plants.

Diatomaceous Earth

Diatomaceous earth is one of the most used products when it comes to eco-friendly agriculture in order to fight various different types of insects off. Thanks to its ingredients, it’s capable of dehydrating and perforating the shell of any insects that come into contact with it. It stimulates plant growth and it improves the actual characteristics of your plants’ substrate.

How to Get Rid of Thrips on Cannabis Plants | What to Do next

After having had your plants viciously attacked by this annoying, hard to kill insect, we highly recommend cleaning the plant and substrate in order to remove any leftover feces and possible eggs that may still be hanging around, capable of causing them to rear their ugly head again. The best way to do this is to use insecticidal soap; this product cleans your entire plant and it’ll get rid of any leftover insects or eggs thanks to its insecticidal properties. We also recommend disinfecting your entire grow room and throwing your substrate out once finished.

Hopefully now you have a clearer idea on how to get rid of thrips on cannabis plants; if this article helped you out or you have any questions, drop a comment below letting us know and we’ll get back to you!

Figuring out how to get rid of thrips on cannabis plants used to be a bit of a pain, but by following these steps they'll definitely be gone in no time!