If you grow plants by seed or clone, beware of powdery mildew infestations. Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are spread through the air, so it is an airborne disease. Powdery Mildew is one of the easier diseases to spot since the symptoms are distinctive.
Introduction to Powdery Mildew and Growing Your Plants
What does powdery mildew look like on your plants?
Infected plants display white powder-like spots on the leaves and stems. Plants may look like they were dusted with talcum powder or flour. A white, dusty coating on leaves, stems and flowers will be visible – starting out as little patches on the leaf surfaces and growing to the point of coating the entire surface of the leaves. Powdery mildew is obvious to see as long as you’re paying attention to your plants.
When dealing with instances of powdery mildew, early detection provides the best way to contain and potentially eliminate the problem. There are many commercial products that are effective at containing the spread. However, eliminating it once it has established itself in the garden is extremely difficult. Most conventional products are made for prevention and control, not elimination of an existing infection. That’s why it’s important to prevent powdery mildew, or at least identify it at the earliest sign of detection.
What causes powdery mildew?
Poor air circulation, dense plant canopies, and high humidity at night followed by low humidity during the day – these are all factors that greatly encourage powdery mildew growth. Do your best to avoid these conditions in your grow room. Create good airflow through and around the plants, and control your humidity as best as possible.
What to do if you see powdery mildew in your garden?
Remove, prune out and destroy infected parts, and clear dead leaves from the base of plants etc.
Conventional powdery mildew cures:
Potassium bicarbonate:
Potassium bicarbonate is a contact fungicide which kills the powdery mildew spores quickly. In addition, it’s approved for use in organic growing.
Sulfur and Lime/Sulfur:
Direct contact by sulfur prevents disease spores from developing. When mixed with hydrated lime, the solution will penetrate leaves for even greater effectiveness. A widely available version of this combination includes copper sulphate and hydrated lime, known as Bordeaux mix. However, all of these solutions can burn plant tissue and is damaging to microorganisms in the soil and harmful to beneficial insects. It is also considered moderately toxic to mammals and humans. Use sparingly and with caution if at all.
Neem oil:
This is a readily available organic option to disease and pest control. Neem oil is extracted from the neem tree, native to India. This is an effective disease control and a broad spectrum, natural insecticide that is kinder to beneficial insects and mammals. As for controlling powdery mildew, results vary but it is not the best option. Results are usually moderate at best.
Once powdery mildew is eliminated in the grow room using an aggressive treatment, environmental conditions should be corrected to discourage powdery mildew in general. Then it’s advisable to spray all the vegetative plants on a weekly basis to prevent any new outbreaks.
Powdery mildew prevention:
My best recommendation for powdery mildew prevention spray is by a company called Mammoth. Their product is called CannControl. This spray controls powdery mildew, as well as all the major pests that plague growers. Other products like Trifecta and Organocide are popular preventatives to consider.
Air purifiers by AiroClean420 are also recommended to prevent powdery mildew for indoor grows, small and large. They pull air in and explode contaminants like powdery mildew spores into nothing but water vapor. The technology used is photocatalytic oxidation.
Air filters (hepa filters) can also be used in grow rooms. Here you’re pulling outside air in and you’d use a filter to trap contaminants before they reach reach your grow room. However, filters like these need to replaced regularly, or else all the trapped contaminants will eventually get blown right into your grow room. Be careful with filters.
An ounce of prevention is worth a pound of cure, especially with regard to powdery mildew and growing your plants.
