How to combat white spider mites in marijuana crops

The white spider mite is one of the most common and damaging pests in cannabis cultivation, causing stress to the plants and reducing yield quality, sometimes even destroying the entire crop. Controlling this pest is challenging, so understanding its characteristics, symptoms, and elimination and prevention methods is essential for a healthy growth.

What is the white spider mite?

The white spider mite, or Polyphagotarsonemus latus, is a microscopic mite that feeds on plant cells. Although it is a small pest, its ability to multiply rapidly and affect a variety of crops, including cannabis, makes it a significant threat. It tends to affect a variety of crops such as apple trees and grapevines.

This pest hides on the underside of leaves, where they lay their eggs, so it can be difficult to detect with the naked eye, which is why it is considered a silent pest. This is due to the fact that they feed there, leaving behind a toxic saliva that causes malformations, stunting plant development.

In general, this pest is located in the upper part of the plant, where the newest shoots are located.

Characteristics of the white spider mite

Identifying white spider mites and acting quickly is key. Here are some of the main characteristics of this pest:

• Size: Females are about 0.2 mm, and males are around 0.1 mm, requiring a magnifying glass for clear observation.
• Rapid reproduction: Especially in warm, humid environments, they reproduce quickly, laying hundreds of eggs per life cycle.
• Widespread presence: White spider mites can infest nearby plants if not controlled.

White spider mites and cannabis

White spider mites pose a high risk to cannabis plants by sucking the sap from leaves, weakening the plants, and slowing growth. Infestation leads to a considerable decrease in quality and yield, as affected leaves lose their ability to photosynthesize efficiently.

Symptoms of white spider mite infestation in cannabis

Recognizing white spider mite symptoms early is crucial to prevent severe damage. Look for the following signs:

• Leaf discoloration: Leaves may develop small yellow or white spots from sap sucking, and both leaves and stems may turn yellow.
• Leaf curling: Leaves may deform and curl, a clear symptom of stress from the infestation.
• Reduced and stunted growth: Infected plants grow slowly due to nutrient loss.
• Fine webbing: In severe cases, delicate webs can be seen on the underside of leaves, with visible mites and eggs.
• Wet, shiny leaves: Flowers may turn brown and rot over time.

Early detection of these symptoms is crucial to take immediate action and prevent the spread of mites to other plants.

How to eliminate white spider mites from your grow

Eliminating white spider mites can be challenging, but these methods can help control them:

Remove infested areas

First, remove any leaves or buds that contain mites or eggs, which eliminates a large number of mites immediately. After removing infested areas, clean thoroughly to minimize damage and prevent further spread.

Neem oil

When you have finished with the affected areas, it is best to spray the rest of the plant with a product such as Neem Boom to get rid of any mites or eggs that may remain. Many growers use neem oil for this, as it kills the pests but does not contaminate or leave residues that can reach people when smoked.

This oil is very easy to use, simply fill the sprayer following the instructions on the bottle and apply it to the affected area of the plant. It is applied the first time, avoiding spraying directly on the buds whenever possible.

Observe for 1-2 days before reapplying this oil a second time. In case of severe infestation it can be sprayed daily, keeping in mind that this will cause more stress to the plants.

Insecticidal soap

This option is perfect for small infestations and in flowering plants, applying them several times for best results, but always avoiding applying them on the buds. In case the plant is not in bloom, it can be applied all over the plant at the slightest sign of flowering.

Natural predators

The introduction of predatory mites, such as Amblyseius swirskii, can be an effective solution in large crops. These mites feed on white spider mites and other white mites, which help reduce the population naturally.

They should be applied at the top of the plant with the youngest shoots where most of them will be found. This is a very effective method, especially during the first stage of an infestation. Even so, in case of a pest it may be necessary a greater number of times.

Pesticides and miticides

In severe cases, synthetic chemical solutions, such as miticides or insecticides, may be necessary. Apply to affected areas and let sit as directed. Some infestations may require multiple applications, but once eradicated, a root wash is recommended.

Prevention strategies for white spider mites in cannabis

Preventing white spider mite infestations is the best way to protect your cannabis plants. Here are some effective prevention strategies:

• Maintain good ventilation: Airflow helps reduce humidity, an essential factor in preventing white spider mites.
• Inspect plants regularly: Frequent inspection of leaves allows for early detection of any signs of infestation.
• Control temperature and humidity: Keeping the environment at optimal conditions reduces pest growth. White spider mites prefer warm, dry conditions, so controlling temperature and humidity helps make the environment less attractive to them.
• Use natural barriers: companion plants like basil or cilantro act as natural repellents and can be planted nearby to deter mites.

White spider mites can pose a serious threat to cannabis cultivation, but with early detection, proper treatment, and preventative strategies, you can control them and protect your plants’ health.