Hemp Russet Mites: What You Need To Know

Hemp Russet Mites: What You Need To Know
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If you grow cannabis plants, then you may have a problem that you can’t even see. And they’re called Hemp Russet Mites.

These little pests cause major damage to cannabis plants if left untreated. In fact, russet mites to marijuana are like termites to wood.

But unlike termites, it is impossible to see one with the naked eye. You would have to use a magnification of 10x or higher to see one single mite! In this article, we will analyze the hemp russet mites and how to a cannabis grower can get rid of them.

What Are Hemp Russet Mites?

Hemp Russet Mites (or russet mites) are extremely small pests that can cause major damage to marijuana plants.

In fact, they are so small, most cannabis growers don’t realize that they have an infestation until the damage has already been done. (According to the Colorado State University, russet mites are about 0.02 mm.)

When they attack, it might seem like something invisible is causing your plants harm. Russet mites start by munching the leaves towards the bottom of your plant, ultimately eating their way upwards until they reach the top.

Life Cycle And Appearance

Hemp russet mites tend to inhabit dry, warm climates. This explains why they usually procreate during the springtime. They lay clear, round eggs in the spring and take about 8-15 days (based on environmental conditions) to hatch.

Adult russet mites are tiny and wedge-shaped, appearing yellow when clustered. Unlike other types of mites (spider mites, dust mites), russet mites only have two pairs of legs. Russet mite life cycle is around 30 days at around 80 F.

How To Identify Russet Mites

Russet mites are too small for most human eyes to see unless they are in clusters or groups. Unlike spider mites, they leave no webbing or other secretions when present.

Unfortunately, most people won’t identify them until after they have started doing damage to the cannabis plants. These mites are capable of reproducing indoors and outdoors in warm, moist areas.

Also, they not only growing around marijuana plants but in tomato-growing regions such as Florida. In the past decade, russet mites have predominantly spread from cannabis-growing sites in California north to Oregon. Hemp russet mites are so infectious because they are small enough to hitch a ride on just about anything.

This includes:

  • Clothing
  • Seeds
  • The wind
  • On flying insects
  • Dried plant matter and more

The mites seem particularly attracted to flower resins and will congregate in flowers and blossoms where they can effectively hide and do great damage.

Damage By Hemp Russet Mites

One crazy fact about hemp russet mites is they lay between 10 -50 eggs inside the marijuana plant and feed around the leaves. This is how they go undetected and start doing damage to the marijuana plant, the leaves in particular.

Yellowing And Browning Leaves

Hemp Russet Mites

Russet mite damage typically presents itself at the bottom of the plant and moves upwards as the mite population does. The first sign of this damage is the marijuana leaves turning yellow and brown.

This discoloration of the leaves is a result of the larvae (from the mite eggs hatched on the leaves) eating in a circle around their egg. The yellowing/browning is caused by mites piercing plant cells and feeding off the contents.

As the damage progresses, leaf edges may appear burned and necrotic.

Leaves Curl At The Edges And Drooping

If you start noticing the yellowing/browning of leaves, the russet mites have likely been living there for several months now. If this problem persists, the next step is for the leaves to curl at the edges and start drooping.

Stunted Growth

When the marijuana leaves start showing the ill-effects of the russet mites, this can only lead to one thing: stunted growth. Continuous exposure to these mites will reduce the plant’s vigor, overall health, and the ability to grow.

In fact, long-term exposure to russet mites not only affect the leaves but the stems as well. By taking away the stem, this saps away the plant’s nourishment, leading to less vigorous green growth and flowering.

Crop Destruction

As the mite problems become more widespread, this eventually leads to entire crops being destroyed. Most cannabis growers will be unable to detect the early signs of crop destruction unless they catch the early signs (e.g. yellowing of leaves).

However, in some cases, the entire crop is already unusable by the time signs of damages are showing. The mites will eventually sap each and every plant until the whole crop is contaminated.

Symptoms of Hemp Russet Mites

As discussed, here are the symptoms of hemp russet mites:

  • Yellow or brown spots on leaves
  • Leave curl at edges
  • Inability to grow more marijuana
  • Yellowing or browning of leaves
  • Leaves look like they have heat damage or burn
  • Leaves look droopy
  • Leaves show signs all over the marijuana plant not just in specific areas
  • They will be next to the vein of the leaf, use a microscope to diagnose

There is also another sign that your cannabis crop is going through a russet mite infestation.

May Look Like An Over Watering Problem

One issue some marijuana growers (especially beginners) encounter is overwatering their crops. Overwatering is simply putting too much water on the plants.

Doing this can lead to mold buildup, a perfect climate for damaging pests such as root aphids and fungus gnats. Basically, overwatering deliver similar types of damages to the crops as hemp russet mites. (e.g., Leaves curl downwards, leaf tips turn yellow, leave dropping)

Can Be Confused With Other Infestations

As just mentioned, overwatering marijuana crops can lead to infestations of other pests that can cause identical damage to russet mites. Russet mites infestation also be confused with another type of issue: Tobacco mosaic virus.

Tobacco mosaic virus is a positive-sense single-stranded RNA virus, genus tobamovirus that infects a wide range of plants, especially tobacco plants. It causes similar issues of mite infestation such as yellowing and/or curling of leaves.

How To Get Rid Of Hemp Russet Mites

Now that we have thoroughly discussed the various ways that hemp russet mites thrive and survive, let’s look at some methods on how to get rid of them.

Green Cleaner

This product is an all-natural cleaner designed to rid marijuana crop of russet mites infestation. It kills mites and their eggs and be applied to plants of any age, from clones through harvest.

Bonide Sulfur Dust

Another method that may control and eliminate a mite infestation is Bonide Sulfur Dust. This product can be safely used on marijuana plants to get rid of mites as well as preventing fungal growth.

Bonide Sulfur Dust is also specially formulated for safe use on berries, including gooseberry and raspberry as well as cherries, grapes, citrus, apples, cucurbits, apricots, and currants.


This product is another one that could stop mites in their tracks.

The special feature of Azamax is that does not use hard chemical solvents and uses food grade formulation ingredients to kill mites by starving them and disrupting growth.

Azamax can also control spider mites, thrips, fungus gnats, aphids, whiteflies, leaf miners, worms, beetles, leafhoppers, scales, mealy bugs, nematodes, and other soil-borne pests.

JMS Stylet Oil

This product is excellent to use as a fungicide for powdery mildew, as an insecticide and for virus control! JMS Stylet Oil is a colorless, odorless chemical that acts as a smotherant and prevents insect respiration & spore germination.

In other words, it will proceed to suffocate the russet mites and cut off their ability to reproduce. In addition to mites, JMS Stylet Oil can be used to kill scale, whiteflies, psyllids, and leafhoppers as well.

Final Word

Hemp russet mites is an unseen problem for many cannabis growers. These minute pests have the ability to wipe out an entire crop if not dealt with in a timely fashion. So if you are a cannabis grower, be sure to check your crops daily to ensure they are healthy and show no signs of mite infestation.