Damping off in cannabis crops: what is it and how to prevent it?
Few growers may have gotten rid of the so-called Damping Off , also called fungal wilt seedbed disease. It is quite common, from one moment to another we find our small seedlings lying on the substrate and with the stem bent. And in 90% of cases, the plant ends up dying.
It is a cryptogamic disease , that is, a plant disease that is caused by a fungus or any other parasitic filamentous organism. And not because of a specific fungus, but there can be several such as Botrytis, Phythium, Fusarium or Sclerotinia.
The spores of these fungi are generally found in all types of unsterilized substrate. Or it is enough that in a sterilized one, favorable conditions are met for its development, so that the spores invade it. Lack of ventilation, always flooded substrate, high temperatures and high humidity, are breeding grounds for all types of fungus.
Damping Off generally attacks seeds and young seedlings in their first days of life. And in the vast majority of cases in seedlings, it attacks the stem in the shallow area of the substrate. With the vulnerability shown by the stem of a young plant, as we say, the plant in most cases ends up dying.
The seeds can be infected by any of the fungi that cause Damping Off. In this case it usually causes it to darken and soften, killing it even before it can germinate.
When it attacks seedlings, it produces a whitish spot on the stem at ground level. The fine stem thins, bends, and finally breaks, laying the seedling on the substrate.
By affecting the vascular vessels of the stem, the supply of nutrients and water decreases, later showing the leaves a flaccid appearance, as if they lacked irrigation.
How to avoid damping-off?
We have already seen which were the factors that most influence the appearance of this group of so lethal fungi. So we will try as much as possible to avoid them. For example, grow in well ventilated and not very shady areas.
Dark-colored pots should also be avoided outdoors, since they overheat in the sun and this temperature is transferred to the substrate. In addition, you should avoid watering in excess or doing it in the hours of sun or maximum daytime heat.
And with regard to the substrate, always use a preferably sterilized substrate. And if it is not possible, at least use a well composted substrate , since decomposing organic debris attracts many pathogens.
Can damping off be treated?
Being such an aggressive disease and that it attacks during short periods (germination and first days of the seedling), the possible treatments do not usually act in time. The best weapon will always be prevention.
It also spreads very quickly, so if several plants are grown, it is not surprising that they all have the same conditions. If it develops in one, let us fear for all the others.
It is convenient to discard the substrate of a plant attacked by Damping Off, as well as to disinfect the pot well before using it again
The Trichoderma fungus is very effective, widely used for the treatment of seeds and soil for the control of various diseases caused by pathogenic fungi.