Downy mildew

What is downy mildew?

Downy mildew is a cryptogamic disease that develops in plants when a type of fungus grows on them, causing serious illness as it spreads and absorbs the plant’s vital fluids. It significantly affects production, as downy mildew causes leaves to become necrotic and eventually fall off, leading to severe defoliation and leaving the plant without enough energy to carry out its primary processes.

It is very common in other types of plants, just like powdery mildew. In English, powdery mildew is often confused with downy mildew, and like the latter, it is very dangerous and spreads easily. It usually originates in decomposing plant debris found around crops, especially in greenhouses and humid outdoor areas. It appears in the form of yellow spots that spread across the surface of the leaves, eventually drying them out completely until they fall off.

Effects of downy mildew on crops

In marijuana plants, it is common for it to appear in neglected crops, but it is also transmitted through the air, meaning your plants can become infected even if they are well cared for. When the fungi settle on our plant, they attach themselves to all its parts (stems, leaves, and flowers). Therefore, even if it is not visible in one area of the plant, it does not mean the plant is free of the fungus.

The fungi that cause downy mildew are very resistant and their spores germinate easily. Like powdery mildew, it has a colonizing state and a latent state. When they settle on a plant, symptoms may or may not appear, depending on the temperature and humidity parameters of the crop. Its greatest spread occurs with high humidity (+55%) and temperatures ranging from 10 °C to 25 °C. Its spores will be generated at high speed and the growth of its fungal hyphae will begin to create the disease.

When it rains or there is high humidity, we can see the filaments with the naked eye on the underside of the leaves, which will release new spores that can germinate both now and in the following spring when you start a new crop. As the fungus progresses through the plant, it will leave it without leaves. A plant without leaves will not be able to perform photosynthesis, which will paralyze the entire vital process and it will die.

How to eliminate downy mildew?

To fight it, the best thing is to prevent it because, once we have it on our plants, we cannot eliminate it. We can only slow down the reproduction of the fungi to paralyze the plant’s disease. If we use a preventive fungicide like Propolix every 2 or 3 weeks, our plants will be safe all season.

When we detect it on our plants, it may already be too late. It is quite common not to recognize the spots very well and think that the plant lacks fertilizer. The products that stop it are sometimes aggressive to the plant, so it will always be better to prevent than to cure. If we detect it on our plants, we will have to use products to defeat it. For example, we can use Anti Mil from Pro XL, which acts very well as a fungicide without affecting the health of our plant.

How to prevent downy mildew?

To prevent it from appearing on our plants, we must keep our crop clean of plant debris, keep humidity and temperature in check indoors, and, if possible, prune the inner area of the plant that remains most in the shade to avoid humid zones. If we have already had downy mildew on our plants before, it is more than likely that it will appear again, so preventing will not be an option, but an obligation.

To act preventively and correctly in outdoor crops, it is always good to spray preventive fungicide when the perfect conditions appear, such as on hot days after rain or if there is a lot of dew at night. We hope you only know about downy mildew from reading this article because it causes real havoc on marijuana plants.

Products to fight downy mildew

In this regard, we can distinguish between contact, penetrant, and systemic products, which have their own characteristics and levels of effectiveness.

Contact products are characterized by acting only on the area or surface to which they are applied. Their depth in the plant is not very high. In addition, the duration of the product once applied does not last more than a week.

Products with penetrant action are more effective, as they manage to penetrate better into the treated plant, although they do not reach the sap. The duration after their application ranges between 7 and 10 days.

Systemic products penetrate until they reach the sap and, in this way, reach all parts of the plant. Their effectiveness is very high and it is usually the most recommended type of formulation. Their duration ranges between 10 and 15 days and they possess great resistance.

Purolyt

Actually, it is not a preventive or combat product against downy mildew, although this incredible product has the capacity to disinfect and leave completely free of any type of pathogen both the treated area and the treated plants (whether seeds, clones, productive plants, or mothers). It is an ideal product for cleaning all material and the grow room or area before starting, as well as for keeping it in perfect condition by performing a general cleaning every so often.

Fungi Boom Fungicide

It is a product composed of horsetail, an excellent fungicide. From the Boom Nutrients range, it will help you prevent and even combat the development of the most common cannabis fungi. It is essential to maintain strict control in the first and last weeks of your plant, as this is when they are most predisposed to becoming infected with fungi, although you can use this product once some type of fungus has already appeared on your plant thanks to its great fungicidal power.

Fungi Boom

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6,90 €8,62 €20%

Domark Evo Fungicide

It is a powerful product used as a preventive in various crops due to its great effectiveness. It also acts by stopping the advance of the fungus and keeps colonization at bay, which gives us room to be able to harvest without the plants failing. To obtain good results with its application, it is necessary to spray it on the crop every 10-15 days as a preventive measure, and if we want to do it in a combative way, it should be applied every 10 days.

Recommendations

Before starting to set up the indoor grow room or preparing the area or land for outdoor cultivation, the first step and one of the most important is disinfection. The reason is that we cannot see if the area, the material, or the environment are contaminated by some type of fungus or pest that could ruin all our enthusiasm, effort, and investment.

The next point that should be taken into account is prevention and maintenance since, as you have been able to verify, once downy mildew has appeared, there is no turning back. The damage will be greater and greater and we could suffer significant losses. Therefore, the continuous application of phytofortifying and preventive products every 10-15 days is of vital importance. Even so, it may manage to appear in well-treated and worked crops, but the destructive effect will be reduced considerably.