Major cannabis diseases in the outdoors
Growing cannabis outdoors is the easiest and cheapest way to get marijuana for personal use. However, outdoors growing also presents a number of additional problems due to external conditions, particularly the relatively cool and humid climate of the midlands. This combination creates favorable conditions for the development of fungal diseases – mold and rot, which are the main danger for outdoor growers. Fungal spores are extremely resistant to external conditions. They can be blown by the wind for many kilometers or remain in the ground for years, waiting for favorable conditions to start developing.
Affects cannabis stems and inflorescences. Infestation can be detected by brown, soggy spots on the plant stems (more often in the root zone). They are covered on top with a dense white fungus with a black mesh of sclerotia. In addition to hemp it can infect other kinds of cultivated and wild plants. In late summer and early autumn it can be transmitted not by spores but by wind-borne mycelium particles.
The main danger comes to ripening inflorescences-affected buds become covered with a gray fluffy coating and rot. On the stems appear wet brown spots, with the same plaque. Where gray rot develops, the outer sheath of the stem softens and loosens, and as a result, the stems may break off. During prolonged rains, especially in dense plantings, mass plant infestation can occur.
Conditions for development are high humidity and poor air circulation. Such a situation can occur during prolonged rains, in windless cloudy weather. Especially if hemp is planted in a natural shelter, such as the slope of a ravine or a small clearing surrounded by trees and shrubs. More often the disease begins on the lower leaves of hemp, deprived of sunlight and natural blowing of fresh air.
Septoriosis (white leaf spot disease of hemp leaves)
White, yellow or ochre spots with dark dots of pycnidia (fruiting bodies of the fungus) are a sign that the plant is infected with the Septoria Cannabis Sacc. fungus. Because it is a specific disease that affects only cannabis, the likelihood of it developing is greatly increased when cannabis is planted in the same location for several years. In the first year, the likelihood of septoriosis is negligible.
Treatment of fungal diseases
Since all of the above diseases have a similar cause – the development of one or another kind of fungus on the trunks, leaves or inflorescences of the plant – then the methods of combating them are similar to each other. First of all, it is to remove the affected parts of the plant, to prevent the spread of mold (the exception is powdery mildew, a plaque of which you can try to remove with wet or soaked with a disinfectant solution cloths).
If the plants have not yet entered the flowering stage, you can use cardinal means – chemical antifungal preparations. These can be specialized solutions sold in most garden and garden stores, or long-established preparations such as Bordeaux liquid, soap and copper sulfate, soda and salicylic acid solutions. In many cases, pollinating plants with ground sulfur helps.
The appearance of fungus on flowering plants when there is very little time left before cannabis harvests is one of the most unpleasant events possible during cultivation. If the disease is detected at a very early stage, an alcohol solution (about 70%) can be used to treat the lesions. Also, if you still have two to three weeks to spare, you can use organic fungicides, which decompose and are eliminated from the plant in about this time.
Preventing fungus development
Any nuisance is easier to prevent than to deal with its consequences. Here are a few tips that will reduce the likelihood of cannabis contracting fungal diseases:
Before planting, inspect the site of the future plot – if the plants show signs of fungal infestation, then most likely the same fate awaits the hemp planted in that place.
Preferably do not plant in natural soil, but in specially prepared and sterilized cannabis soil, with the addition of perlite or vermiculite.
Placing the shrubs in groubegs (special agrotextile bags) improves the aeration of the roots and the natural ventilation of the root zone. This method also prevents the accumulation of excess moisture in the soil.
Immediately remove any damaged parts of the plant or, if rot is far enough along, remove the whole plant. If conditions are right for the fungus to grow, it will spread to the whole plantation very quickly.
If you want to be sure to choose the right strain, this is an important step in the prevention of disease. If you’re experiencing a cold, rainy autumn, choose early maturing cannabis plants that will have enough time to ripen before the rains come in.