Hola friends of the most beautiful plant in the world,
Today we are talking about an unpleasant thing, namely botrytis (grey mould). Unfortunately, many growers both indoors and outdoors know about the problem, so what can be done about it?
Grey mould (lat. Botrytis cinerea) is a fungus genus that belongs to the moulds and forms cotton-wool to fluffy coatings. The colour changes from initially white to grey, hence its name. It can also be the cause of falling sickness in young plants. Apart from the fact that mouldy weed tastes quite unimpressive, it is also harmful to health and can severely stress and even damage the respiratory tract.
Indicas in particular are often affected by mould towards the end of the flowering phase. This is due to their thick, firm, often hard buds that let little to no air through and thus have a warm, humid climate inside, which is unfortunately ideal for the spread of botrytis. In the finer, airy sativa flowers, grey mould has much less chance of spreading and occurs much less frequently there. Grey mould often starts in the middle of the flowers, especially in large and dense buds, and can very quickly destroy the entire crop. Often the buds look normal from the outside, while the mould spreads inside the flower. Botrytis spreads most easily on damaged tissue, especially in damp and cool climates. This is why it often occurs outdoors in autumn, when the flowers are in full bloom, and also in grow rooms the temperatures drop in winter, so that many Indoorgrowers also know the annoying problem. As already mentioned, it is difficult to detect it right at the beginning, as it always starts to grow deep inside the flower. It spreads quite slowly at first, but once it has taken hold, it really eats up the flowers.
If you discover mould between the buds, cut them off immediately (better to sacrifice a few centimetres of healthy plant than to mess up the whole grow) and burn the infected areas immediately, so that no more spores can spread. But never burn them in the bag or bong!
There are various chemical remedies against botrytis, but on the one hand they are harmful and you don't want to grow contaminated weed, and on the other hand grey mould unfortunately develops resistance very quickly, so that they only help to a limited extent.
Therefore, one should take preventive action above all:
- Use of so-called antagonists, i.e. opponents. In our case, these are other fungi or yeasts that compete with the grey mould because they spread faster and thus deprive the grey mould of space and nutrients. Examples are Trichoderma spp. and Pythium oligandrum. There are special preparations for cannabis cultivation for this purpose, e.g. Hesi Power Zyme.
- Use of general strengthening agents for the plants, either through soil bacteria such as Bacillus subtilis, which are intended to stimulate growth and resistance by improving root growth, or through the application of fatty acids and trace elements, which, in addition to increasing the plant's own defences, also strengthen the plant's cell walls so that fungal spores can no longer penetrate the plant so easily, e.g. GHE Organic Essentials, Mineral Magic, Rhizotonic, Vita Race, CANNAZYM or Neudorf Horsetail Extract.
- Ventilation should be sufficient and fans must also be used in the growroom so that the air is kept moving.
- The humidity in the grow room should not be too high. The planting medium should be moist, but not wet. Ensure sufficient ventilation, especially in the morning and evening, as this is when the humidity is highest.
- Do not spray buds with water, as this may not be able to dry off and mould will quickly form!
- Always look for healthy and uninjured plants. Botrytis always attacks weakened, diseased tissue first. Once it has invaded the plant, it spreads to the healthy part as well.
- Over-fertilisation promotes the formation of mould, especially too much phosphorus can extremely weaken the plant.
- Absolute cleanliness in the growroom! Remove old, dead leaves and also cut off weak shoots in the lower part of the plant with a disinfected, sharp knife so that more air gets to the strong shoots.
Botrytis is a very sneaky and destructive fungus. Therefore, always pay attention to cleanliness and healthy plants. It is better to invest 5 minutes more time than massive losses or even complete crop failures. If you have had frequent problems with fungus or mould on your cannabis plants, there are also some strains that have a high resistance to these diseases, for example Silver Bubble from Reserva Privada, Malakoff from medical Seeds, Swiss Cheese by Nirvana, Sweet Purple by Paradise Seeds or Diamond Cream by Anesia Seeds.
With this in mind, have a fungus and mould free grow season,
Your Juan
