by Nebula Haze
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 marijuana plant. They live the crevices of leaves, stems, or buds, and the initial symptoms are not that serious. Many cannabis growers may not realize they have a bug infestation of hemp russet mites, 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.
Hemp russet mites often cause curling on the edges of cannabis leaves. Another symptom of hemp russet mites is buds 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 yellow fuzz is sometimes confused for yellow mold, but it’s not mold. The yellow stuff is actually a result of the hemp russet mites. This cannabis 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 hemp russet mites on the petiole of a cannabis leaf.
These microscopic four-legged mites infested cannabis hemp plants in a greenhouse at Indiana University. This picture shows hemp russet mites 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 leaves or stems that may 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 and is often confused for mold, underwatering, root problems, or other environmental cause.
The yellow mass of the tops of this cannabis plant 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.
Prevention
- 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.) 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
3.) 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!
4.) 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!
5.) 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!
6.) 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!
7.) 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.
8.) 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!
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