How to prevent and combat the annoying whitefly in your cannabis grow

Self-growing cannabis can involve many challenges. One of the most feared ordeals is having to deal with pests, as these may affect or even ruin entire crops. One of the most common pests is the whitefly, an insect that is not the most lethal for marijuana, but it usually appears frequently and can affect the development and yielding potential of your plants. Here we explain how to prevent its appearance and how to eliminate it.

Whitefly, also known as glasshouse or greenhouse whitefly, is a type of homopteran insect from the Aleyrodidae family. It colonised the agriculture sector a long time ago, becoming an annoying pest for fruits, vegetables, and ornamental plants. In fact, as it is capable of decimating more than 50% of the yielding capacity of plants, it is regarded as one of the most threatening pests in the farming industry worldwide.

With over 1500 known species of whitefly, Trialeurodes vaporariorum is one of the most common in cannabis cultivation. Although it is not as devastating a pest as caterpillars or red spiders, its ability to significantly reduce the yield of both indoor and outdoor marijuana crops should not be underestimated.

These small insects are approximately 1 – 2 mm long. They have a yellowish body and four wax-coated wings held parallel to the body while they rest. They feed on the sap of the plants using piercing and sucking mouthparts. This pest can spread at high speed, since females are able to copulate just 24 hours after hatching, and often leave their eggs on the underside of the leaves, depositing between 150 and 500 of them.

The life cycle of whiteflies comprises the egg, larvae, pupae, and adult stages, and is completed in about thirty days. This is why prevention and early detection are crucial to prevent this plague from spreading and causing havoc in cannabis grows.

How to prevent whiteflies in marijuana growing

The golden rule for any self-respecting grower is prevention because that’s the only way to avoid any future headaches. There’s nothing more discouraging than investing time and energy in growing cannabis, and then seeing your crop spoiled by pests, fungi, or diseases.

To prevent this from happening, here are some simple tips to keep your marijuana grow free from whiteflies:

• Check your cannabis plants regularly: Whiteflies are easy to detect, especially in their adult stage, as they tend to hover around the plants. And they’re not very fast, so you won’t find it too hard to spot them.
• Use companion plants: If you’re growing outdoors, you can place other plants around your cannabis grow which act as a repellent for whiteflies. These include marigolds, Chinese carnations, and basil.
• Use biological insecticides as a deterrent: It can be very useful to spray your plants preventively using a solution based on horsetail, Neem oil, or potassium soap. But remember: even though these are biological insecticides, if you’re going to use them exclusively for preventive use, you should only spray your plants when they are in the vegetative phase.
• Avoid excess nitrogen in your nutrient solution as it may attract whiteflies.
• Good ventilation: Make sure the air circulates properly through your marijuana grow. This will not only help you to avoid whiteflies but will also prevent the appearance of fungi.
• Maintain strict hygiene conditions in your grow to avoid possible contamination.
• Use yellow adhesive traps to detect the arrival of flying adults. They’re particularly useful in determining the degree of infestation.

How to identify whiteflies in your cannabis grow

Detecting whiteflies on your marijuana plants at an early stage will be crucial to preserving the health of your grow. This insect initially settles in the highest part of the plants before gradually moving downwards.

As this plague spreads, and more individuals feed on the sap of the cannabis plants, the signs of their presence become more evident, as the vigour and chlorophyll levels become affected. These are the main signs to look out for when whiteflies have settled in your grow:

• Flies flying away clumsily when the plants are shaken.
• Yellowish or dry leaves, suffering from chlorosis.
• Appearance of honeydew, a by-product of their feeding that they secrete through their anus, and which can be the gateway to fungi.
• Translucent stippling on the leaves, which are the marks left by the whiteflies after they’ve been sucking the sap.
• Whitish powder on the underside of the leaves, as well as in adult individuals.

What damage do whiteflies cause in cannabis grows?

Whiteflies feed by sucking the sap from the plants, which significantly affects their overall health. If this pest appears during the growth phase, it can slow down or even stop plant development, leading to leaf loss in severe cases.

During the flowering phase, a whitefly attack can reduce the number, volume, and quality of the buds, and even delay their ripening. As if this weren’t enough, their bites can introduce toxins into the plant, which can act as a vector for the entry of fungi like smut or sooty mould. And what’s worse, they can transmit various viruses that are harmful to plants.

How to eliminate whiteflies

But if whiteflies have already settled in your grow and it’s too late to apply the prevention methods above, a quick reaction will be essential to stop them from spreading further. The control methods currently used to control this pest in the agricultural sector are characterised by the frequent application of synthetic insecticides, which has led to these insects developing a resistance to them. Therefore, it is best to go for a cannabis grow that’s as organic as possible, by following these recommendations:

• Introduce predatory species: the parasitic wasp Encarsia formosa, for instance, is highly effective. Other species include the predatory mite Amblyseius swirskii and the heteropteran insect of the Miridae family Macrolophus caliginosus ― a creature with a voracious appetite that not only gets rid of whiteflies, but can also be effective against red spiders.
• Place yellow adhesive traps. These attract white flies when they’re flying around the plants, so they end up sticking to them.
• Manually remove the eggs and larvae on the underside of the leaves with a piece of cottonwool soaked in some biological insecticide. Eggs are pale yellow, although they gradually change colour until they reach a greenish tone before the larvae are born.
• Spray biological insecticides repeatedly: For instance, pyrethrum, potassium soap, or Neem oil (it showcases anti-feeding effects, by inhibiting growth and intervening in endocrine processes).

Whiteflies can become a real challenge for those venturing into the beautiful art of cannabis self-cultivation. The implementation of preventive measures, as well as the proper eradication of this pest, can make all the difference between a poor yield and a yield full of aromatic flowers. Now that you know all our top tips to keep this plague at bay, you just need to germinate our powerful cannabis seeds to turn into a real pro!