Fungus Powdery Mildew

Indoors, as we mentioned before, Powdery Mildew is an increasingly common disease and in some cases it’s necessary to take preventive measures from the beginning of the crop, but what will help us more to avoid this pest is to control the climate of our growing space. The aim is to prevent that the relative humidity of our grow room neither exceeds 65% nor goes down under 40%. To do this perhaps we will need a humidifier, to avoid that – with the lights turned on – the humidity doesn’t descend too much due to the effect of the heat from the bulbs. During the night hours of our plants, we should adjust the ventilation so that plants don’t produce condensation inside the growing room. In extreme cases we can use a de-humidifier. Another detail that can help to prevent the propagation of the fungus is to leave enough space between the cannabis plants, because shady areas are formed in the lower parts of the plants when they are too close, what favours the appearance of Powdery Mildew.

It’s a parasitic fungus of the family of the erysiphales, which attacks the aerial parts of the plants.

Although this infection is relatively easy to cure, it can bring serious consequences, because it can cause damage to crops leaving them absolutely useless. In a first phase it develops on the leafs, to extend then to the petioles, stems and finally the buds, completely destroying the resin and leaving the cannabis plants totally unusable for smoking, since the spores of the fungus are solid matters that we would absorb during its inhalation.This pest affects both indoor cannabis as well as outdoor or greenhouse crops; for its propagation it needs strong humidity variations, a situation found very commonly in crops under artificial lights and in greenhouses. Outdoors the plague is more seasonal and usually appears more often in spring and autumn.

Powdery Mildew is a fungus that is easily diagnosed. It manifests as a typical white powdery that can be confused with dust on leafs and buds. In a second phase the attacked leafs become yellow and end up drying.

Powdery Mildew is an external fungus and its behaviour is very similar to that of sucking insects, since its small spores are carried by the wind and when they lay down on a leaf they put down rootlets that suck and absorb nutrients from the plant.

Powdery Mildew in indoor cannabis crops