Categories
BLOG

russet mite damage cannabis

Hemp Russet Mites

Hemp russet mites are tiny bugs that attack cannabis plants. In fact, they are so small you can only see them with a magnifier unless there are thousands of them infesting your plant. They live the the crevices of leaves, stems or buds, and the initial symptoms are not that serious. Many growers may not realize they have a bug infestation, and it’s common for growers to confuse the symptoms for other problems such as mold, fusarium, pollen, tobacco mosaic virus , overwatering , a nutrient deficiency or heat damage .

You may see curling on the edges of leaves, and buds may start dying (hemp russet mite leaf damage picture by thehumboldtlocal)

Hemp russet mites are tiny. You often won’t see them until you have a full infestation. They may appear as a beige or yellow mass (typically towards the tops of the plant). This hemp russet mites picture is by grow.nation.

The following two pictures of Hemp Russet Mites (Aculops cannabicola) were taken in Bloomington, Indiana by Karl Hillig. This picture shows hundreds of microscopic mites on the petiole of a Cannabis leaf.

These microscopic four-legged mites infested Cannabis plants in a greenhouse at Indiana University. This picture shows them on a leaf petiole that was about 2 mm wide. By Karl Hillig.

Symptoms of hemp russet mites on cannabis include:

  • Symptoms often worst towards the tops of the plant
  • Bugs are pale, typically either tan or yellow. In big enough numbers they can cause parts of the cannabis plant to look beige or yellow.
  • Sometimes mistaken for fungus, mold or pollen.
  • Tops of plants droop, especially where there is a big infestation
  • Curling of the leaf edges (on some plants)
  • Dull-colored and leaves or stems, which may also become brittle. These affected areas are where bugs are living inside the plant tissue.
  • Brown or yellow spots (from leaf stress, not visible bites)

An intense hemp russet mite infestation on cannabis plants can be difficult to diagnose because it’s hard to see the individual bugs

The yellow mass isn’t mold or pollen. It’s actually an infestation of hemp russet mites

About hemp russet mites

  • Can reproduce and attack cannabis plants all year round
  • Most harmful in the flowering stage when buds get infested
  • Indoors, fans can spread mites

Unfortunately, hemp russet mites are one of the toughest cannabis pests to get rid of. They lay their eggs inside the plant which makes it very difficult to kill their eggs.

  • Grow from seeds (hemp mites and eggs cannot survive on seeds). If you start from seeds, your plants will not get hemp russet mites unless they get infected by some other source
  • Treat and quarantine all new plants (even if they seem healthy) to ensure they don’t have hemp russet mites (or spider mites)

Time to get rid of hemp russet mites for good.

Solution: How to Get Rid of Hemp Russet Mites On Cannabis

Once you’ve actually identified that the bugs you have on your cannabis are hemp russet mites, it’s time to get rid of them! When it comes to hemp russet mites, a lot of the “standard” miticides are not as effective and you’ll notice these particular mites aren’t listed on the labels.

Hemp russet mites can be one of the toughest marijuana pests to get rid of, but it can be done if you stay vigilant!

  • Consider tossing your plants – I know it can be a hard pill to swallow, but if you have an intense infestation, sometimes the easiest thing to do is to get rid of the plants, treat the room thoroughly, and start over. However, make sure you know where you got the mites in the first place or you may end up infected again!
  • Treat often – You may have to treat several times a week or even daily if you have a terrible infestation that won’t go away. This can be very difficult on your plants.
  • Spray Before Lights Go Out – Whenever treating plants with a spray, do it before the lights go off so that your plant is less likely to get burned!
  • Read Instructions – Make sure to read the full instructions of each bottle and follow them when treating your plants. You will save yourself a lot of big headaches!
  • Repeat treatments weekly for 5 more weeks after mites are gone – After you think hemp russet mites are completely gone, don’t stop! Treat your plant with a different treatment at least once a week for 5 additional weeks. If you don’t completely eradicate them they’ll come back with a vengeance and be even more resistant to whatever you throw at them.

1.) Neem Oil

Neem Oil will leave an unpleasant taste/smell on buds when used to treat flowering plants, so again, 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, including hemp russet mites.

Neem oil can be rough on your plants so you don’t want to use it more often than you have to because your plants will suffer. However, if you get desparate treating plants daily with Neem oil is very effective at killing hemp russet mites when nothing seems to be working.

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.

2.) Essentria IC3

Essentria IC3 Insecticide is a mix of various horticultural oils that is organic and safe for humans. It is often marketed as a “bed bug killer” but it can be effective against hemp russet mites when the plants are treated regularly. Unfortunately it only stays effective on the plant for about 8 hours so you will want to either apply this daily or combine with other options. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

3.) Insecticidal soaps

Fatty acid salts or insecticidal soaps can be a good choice against hemp russet mites. They weaken the outer shell of hemp russet mites but are safe to use on your plants and they don’t leave much of a residue which could kill beneficial bugs in your garden.

With soaps, just like horticultural oils, 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!

This will not get rid of hemp russet mites on its own, but it is less harsh on your plants than some of the other options and so it can be a great way to supplement the other treatments you’re doing.

Natria Insecticidal soap can be a good option Another insecticidal soap that can be used against hemp russet mites is Safer Brand Soap

4.) Mighty Wash

Mighty Wash may help rid your grow room of hemp russet mites. Spray plants 15 minutes before lights out, making sure to drench the foliage under the leaves as well as the top of your soil. You want to use a spray bottle or mister. Use a fan to blow on your leaves to help things dry. Treat your room more than once, even if you believe the hemp russet mites are gone.

Use Mighty Wash with a One-Handed Power Sprayer for the best results!

5.) Avid

Avid miticide is strong stuff with harsh chemicals, and is incredibly expensive, but it can sometimes do the job when nothing else is working. This is a systemic insecticide, which means it works by infiltrating the inside of plant tissue and killing bugs that way. Because of that it should NOT be using in the flowering stage (you don’t want this stuff inside your buds). However, many growers report that this is the only thing that consistently works for them. Always use Avid as directed and only as a last resort! You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

Don’t use this product more than once or twice in a row or your mites may become resistant. This should stay in your plant’s system for several weeks. If you’re going to be using systemic insecticides, switch back and forth between this and another one like Forbid. Make sure to follow the instructions!

6.) Forbid

Forbid miticide is sort of like Avid in that it is made of strong stuff with harsh chemicals and is also expensive. This is a systemic insecticide, which means it works by infiltrating the inside of plant tissue and killing bugs that way. Because of that it should NOT be using in the flowering stage (you don’t want this stuff inside your buds). However, many growers report that this can be the only thing that consistently works for them. Always use Forbid as directed and only as a last resort! You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

Don’t use this product more than once or twice in a row or your mites may become resistant. This should stay in your plant’s system for several weeks. If you’re going to be using systemic insecticides, switch back and forth between this and another one like Avid. Make sure to follow the instructions!

7.) Diatomaceous Earth

Diatomaceous Earth is basically fossil dust which you mix in with the top of your soil, and anywhere else in your room (window sills, doorways, etc). This powder-like substance is harmless to mammals and plants, but is incredibly sharp at the microscopic level. Therefore it will tear and dehydrate hemp russet mites on physical contact. This will not get rid of an infestation, but can help prevent, control and slow things down when used effectively! When it comes to hemp russet mites, you want to use every tool you can!

8.) Heat

Hemp russet mites don’t like the heat. Some growers will try to get rid of them by on small plants or clones by dunking the plants in hot water (105°F / 40°C) for 10-20 minutes. I’ve also heard of growers try to reduce their number by overheating the grow space to 115°F (46°F) for an hour. Be careful as this can be dangerous if you don’t take safety precautions, and any heat method strong enough to kill the mites will likely hurt your plants.

9.) Predatory Mites

Some types of predatory mites, like Amblysieus andersoni mites, may target hemp russet mites. Supplementing your garden with extra predators can help bring down hemp russet mite numbers. However, it’s not enough to fix the problem on their own and unfortunately a lot of the other remedies on this page may also kill predatory mites.

If you don’t want to use any pesticides, get predatory mites to help eat all your hemp russet mites!

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.

Hemp Russet Mites Hemp russet mites are tiny bugs that attack cannabis plants. In fact, they are so small you can only see them with a magnifier unless there are thousands of them infesting

Broad Mites

Broad mites on your cannabis plants are so tiny they are practically impossible to spot with the naked eye, and can even be difficult to see under a microscope.

Broad Mite Symptoms:

  • Bugs are so small they are difficult to see without magnification
  • Under a microscope, you can see that they have 6 legs when young, and 8 legs as adults
  • Symptoms are often confused for heat stress, overwatering, a pH imbalance, or root problems
  • New growth may be twisted or drooping
  • Leaves may be, blistered or “wet” looking
  • Leaves may be turned up at the edges
  • Broad mites don’t attack all parts of the plant evenly; symptoms are worse in certain spots where the infestation is concentrated
  • In the flowering stage, buds may become sickly and die

With broad mites, the new growth may be twisted, blistered and “wet” looking. If your plant is flowering the buds may turn brown and die. These broad mite damage pics were taken by Hosttrevor (thank you!).

Sometimes one of the main symptoms is the newest growth is coming in twisted

Edges may turn up as if the plant is suffering from heat stress, but with broad the leaves take on a glossy, almost plastic-like appearance. Eventually affected leaves turn yellow or bronze and die.

The main way to spot an infestation is the damage they leave behind because usually the mites themselves are too small to see. They like to hang out inside inside your plants, where they can live and lay eggs without you seeing them.

Sometimes the symptoms can be confused for tobacco mosaic virus. Leaf symptoms from broad mites are also commonly misdiagnosed as overwatering, a nutrient deficiency or heat damage.

One of the biggest reasons broad mites can be so difficult to diagnose is you rarely see any signs of bugs, and you don’t see bites on the leaves. For many people, they don’t even realize a bug infestation is happening.

Sometimes top leaves droop. In this pic you can see that part of the droopy leaves are getting that blistered, wet appearance from broad mites.

The following marijuana plant has been treated for broad mites and is starting to recover. You can see the newest growth looks matte and healthy, while the damaged leaves from before still look glossy and blistered.

It’s great if your plant is starting to look healthy again, but even if your plant appears to be recovering, don’t stop on weekly treatments for at least a few weeks. The broad mites could still be there waiting to take over the plant again! They are the masters of hiding and waiting.

Unfortunately, broad mites are probably one of the hardest marijuana pests to get rid of. They lay their eggs inside the plant which makes it very difficult to kill their eggs!

Solution: How to Get Rid of Broad Mites On Cannabis

Once you’ve actually identified that you have broad mites, it’s time to get rid of them! When it comes to broad mites, a lot of the “standard” miticides are not as effective and you’ll notice these particular mites aren’t listed on the labels.

Broad mites can be one of the toughest marijuana pests to get rid of, but it can be done if you stay vigilant.

  • Immediately and carefully remove infected parts of the plant – if there’s already an infestation in the tissue, you likely won’t be able to save those particular leaves/buds. Your main goal is to stop the infestation from spreading.
  • Treat often – You may have to treat several times a week or even daily if you have a terrible infestation that won’t go away. This can be very difficult on your plants.
  • Spray Before Lights Go Out – Whenever treating plants with a spray, do it before the lights go off so that your plant is less likely to get burned.
  • Read Instructions – Make sure to read the full instructions of each bottle and follow them when treating your plants. You will save yourself a lot of big headaches.
  • Repeat treatments weekly for 5 more weeks after mites are gone – After you think broad mites are completely gone, don’t stop. Treat your plant with a different treatment at least once a week for 5 additional weeks. If you don’t completely eradicate them they’ll come back with a vengeance and can be even more resistant to whatever you throw at them.

Here’s a Detailed Step-by-Step:

1.) Dispose of known infected plant matter

The parts of the plant that are already infested should be carefully removed and discarded of if possible. This will dramatically reduce the bug numbers, and help save the rest of your plant.

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, including broad mites.

Neem oil can be rough on your plants so you don’t want to use it more often than you have to because your plants may suffer. However, if you get desperate treating plants daily with Neem oil can be effective at killing broad mites when nothing seems to be working.

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. A mister helps you get full and even coverage on all parts of the plant.

3.) Essentria IC3

Essentria IC3 Insecticide is a mix of various horticultural oils that is organic and safe for humans. It is often marketed as a “bed bug killer” but it can be effective against broad mites when the plants are treated regularly. Unfortunately, it only stays effective on the plant for about 8 hours so you will want to either apply this daily or combine with other options. Foolow the directions carefully. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

4.) Insecticidal soaps

Fatty acid salts or insecticidal soaps can help against broad mites. They weaken the outer shell of broad mites but are safe to use on your plants and they don’t leave much of a residue which could kill beneficial bugs in your garden.

With soaps, just like horticultural oils, 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 because it can affect the taste or small.

This probably won’t get rid of broad mites on its own, but it is less harsh on your plants than some of the other options and so it can be a great way to supplement the other treatments you’re doing by bringing down their numbers.

5.) Avid

Avid miticide is strong stuff with harsh chemicals and is incredibly expensive, but it can sometimes do the job when nothing else is working. This is a systemic insecticide, which means it works by infiltrating the inside of plant tissue and killing bugs that way. Because of that, it should NOT be used in the flowering stage (you don’t want this stuff inside your buds). However, many growers report that this is the only thing that consistently works for them. Always use Avid as directed and only as a last resort. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

Don’t use this product more than once or twice in a row or your mites may become resistant. This should stay in your plant’s system for several weeks so this is only really suitable for young plants. If you’re going to be using systemic insecticides, switch back and forth between this and another one like Forbid. Make sure to follow the instructions.

6.) Forbid

Forbid miticide is sort of like Avid in that it is made of strong stuff with harsh chemicals and is also expensive. This is a systemic insecticide, which means it works by infiltrating the inside of plant tissue and killing bugs that way. Because of that it should only be used several weeks before the beginning of the flowering stage (you don’t want this stuff inside your buds and it can stay in the plant for weeks). However, many growers report that this can be the only thing that consistently works for them. Always use Forbid as directed and only as a last resort!. You will need a mister (also called a “One-Hand Pressure Sprayer”) to spray all the leaves evenly.

Don’t use this product more than once or twice in a row or your mites may become resistant. This should stay in your plant’s system for several weeks. If you’re going to be using systemic insecticides, switch back and forth between this and another one like Avid. Make sure to follow the instructions.

7.) Diatomaceous Earth

Diatomaceous Earth is basically fossil dust which you sprinkle on the top of your soil, and anywhere else in your room (window sills, doorways, etc). This powder-like substance is harmless to mammals and plants but is incredibly sharp at the microscopic level. Therefore it will tear and dehydrate broad mites on physical contact. This will not get rid of an infestation but can help prevent, control and slow things down when used effectively. When it comes to broad mites, you want to use every tool you can.

8.) Heat

Broad mites don’t like the heat above 90°F (32°C). Some growers will try to get rid of them by on small plants or clones by dunking the plants in hot water (105°F / 40°C) for 10-20 minutes. I’ve also heard of growers try to reduce their number by overheating the grow space to 115°F (46°C) for an hour. Be careful as this can be dangerous if you don’t take safety precautions, and any heat method strong enough to kill the mites will likely hurt your plants.

9.) Predatory Mites

Some types of predatory mites, like Neoseiulus type mites, love to eat broad mites. Supplementing your garden with extra predators can help bring down broad mite numbers. However, it’s not enough to fix the problem on their own and unfortunately, a lot of the other remedies on this page will also kill predatory mites.

If you don’t want to use any pesticides, get predatory mites to help eat all your broad mites.

Broad mites are tiny; they can be almost impossible to spot, and the symptoms may be similar to deficiency. Learn how to identify and get rid of them!