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cannabis powdery mildew

Cannabis powdery mildew

Either add two teaspoons of cider vinegar to 1L of water and spray your plants, or make a mixture of 60% milk and 40% water and spray your plants. Both work to kill Powdery Mildew, but how effective they are is debatable. If you want to avoid fungicides, they are certainly worth a go.

Also, once an infection like this sets into a garden or grow room, it is extremely hard to get rid of permanently. Outdoors they will move from plant to plant, as well as reproduce in the soil as mycelia. Indoors, the spores will sit on walls, floors, and pretty much any surface until they are disturbed and moved. It means you run a real risk of infecting future crops as well.
Without a doubt, prevention is the best way to keep your cannabis safe. It is much easier to take some extra precautions and monitor the state of your growing environment than to try and actually cure an infection.

There are three conditions that need to be met for both Botrytis and Powdery Mildew to take hold. These are:
Of all of the types of moulds and infections out there that can attack your cannabis plant, it is Botrytis (bud rot) and Powdery Mildew that are the most common.
These are all quite easy to prevent indoors. A cool temperature is anything under 20 degrees Celsius. Ensure you have a decent ventilation system set up to ensure constant air movement, and try to prevent overcrowding of plants that may inhibit air flow. You should also be able to control the humidity of a grow room using ventilation, keeping things in order.
Botrytis powdery mildew fungicides infection –>
It is important for every cannabis grower to recognise the signs of a potential mould infestation, and how to prevent it, so we have put together a quick and handy guide with the knowledge you need.

A bit more can be done with Powdery Mildew. Remove infected leaves and move the plant into a warm, low humidity area. Proceed to spray the plant with safe and specialised fungicides that target the mildew. This should hopefully keep the infection at bay.

A mould infection is every cannabis grower’s worst nightmare, so here is how to spot it, and prevent it from ever happening in the first place.

Cannabis powdery mildew

According to several studies plants such as cucumber, tomato, salad, potted herbs, and strawberries treated with Milsana® were significantly less infected than controls and this protective effect against powdery mildew was maintained over time. When topically applied to various ornamental, vegetable and fruit crops, this product will induce increased amounts of naturally occurring phenolic substances within the plant, which prevent the attack of plant diseases such as powdery mildew and grey mold (Source: Physiological and Molecular Plant Pathology – Volume 61, Issue 2, August 2002, Pages 121-132) . On ornamentals and strawberries it is also effective against Botrytis or grey mold. It remains to be seen if it has the same effectiveness for marijuana.
Available in Europe at and

We use several methods to ensure plant resistance is maintained or optimally enhanced in the Mandala strains:
Garlic is cheap and readily available. This has made it a favourite “home-grown” pest control, especially among organic gardeners. The volatile antimicrobial substance allicin (diallylthiosulphinate) is produced in garlic when the tissues are damaged during crushing or chopping the garlic. Allicin in garlic juice inhibits the germination of sporangia (in which the spores develop) and thereby acts as a fungicide. You can buy readymade garlic extracts that are very effective in three ways: as a natural insect repellent, as a fungicide, and plant strengthener. Alternatively, you can make your own juice by using a homemade recipe. Garlic extracts are not suitable for seedlings and should not be applied under direct sunlight.
Garlic GP Ornamental Fungicide is a commercial product available in North America.

Health Warning
Infected leaves or buds should not be smoked or used for cooking!

Powdery mildew is one of the most widespread plant pests. It tends to affect flowering plants and fruit trees or bushes (roses, apple trees, etc.) as well as cannabis. The spores are in the air or on contaminated plants in the garden and can easily be drawn into your grow room by ventilators. In internet forums and cannabis cultivation books you may find lengthy lists of possible treatments that look temptingly promising for a complete recovery at all stages of mildew infestation. But the authors have rarely tested these products themselves, and the compounds are seldom differentiated between those applicable only for growth, and those also safe to use during flowering. This guide is therefore specifically orientated towards publishing some first-hand experiences with a variety of fungicides, and a review on the specific utilisation of products during growth and flowering in cannabis plants.
GreenCure® can be used as a good preventative control of powdery mildews by applying 1 tablespoon per gallon of water every 1 to 2 weeks when environmental conditions are ideal for the disease. In cases of moderate to severe infestation GreenCure® can be used to eradicate plant disease by spraying plants completely with a mixture of up to 2 tablespoons of GreenCure® per gallon of water weekly for 3 weeks followed by the preventative program thereafter. GreenCure® kills mold/mildew spores within seconds of contact by causing an immediate dehydration of the spores and destruction of the cell walls. In a greenhouse it is important to spray at times when the sun is not shining as this can cause burning on recently sprayed, wet leaves. For indoor gardens with high intensity lighting it is best to turn lights off after spraying in order to let GreenCure® air dry to avoid burning from hot, intense lighting. Infected plants should ideally be moved to a separate and shadier area after treatment. Lamps can also be hung further up for a few days as an alternative. Potassium bicarbonate is not suitable for treating seedlings and should not be sprayed directly on flowering buds. Therefore, you have to treat leaves carefully with a hand-held spray pump and avoid contact with the buds. Treated leaves should not be smoked . More info under:
Regalia® is also a patented formulation of an extract from the Giant knotweed plant and sold in the USA. Regalia’s unique mode of action switches on the plant’s natural defence mechanisms to inhibit the development of major diseases, including powdery mildew and grey mold. Research shows after treating with Regalia®, plants produce and accumulate elevated levels of specialized proteins and other compounds known to greatly inhibit fungal development. For example, Regalia® will induce a plant to produce cell strengtheners, antioxidants, phenolics, and PR proteins, which are known to fight pathogens that infect plants. Additionally, Regalia® causes an increase in the production of phytoalexins, the “antibiotics” produced by a plant under attack. These act as toxins to the pathogen such as mildew. More info under

  • good plant tolerance
  • not harmful to flowering buds
  • effectiveness for medium to heavy infestation
  • effectiveness as a preventive product
  • not toxic for humans
  • environmentally friendly (pets, water sources, honey bees, etc.)

With less new fungicides coming on the market due to environmental concerns, more scientific effort is now being put into the use of the genetic potential of plants for pathogen resistance. In addition, scientists are focusing on exploring the development of induced or acquired resistance as an environmentally safe means of disease control. In our breeding projects at Mandala Seeds the immune system and resistance of a strain has always belonged to one of the high priorities. In the OUTDOOR GUIDE of our website you can also check which Mandala strains have been tested for mildew resistance and this helps in selecting the appropriate strain for your region.

Prevention and treatment of powdery mildew on cannabis and marijuana. Mandala Seeds ensure plant resistance is maintained or optimally enhanced