Powdery Mildew

Powdery Mildew can be a problem growing both indoors and outdoors. Powdery mildew is one of the more common diseases that you see on ornamental plants as well as vegetables and herbs. It is easily recognized by it's gray, powdery spotting that covers the bottom and sometimes the top of the leaves. I have even seen cases where the stalks of plants and even the flowers and buds of plants were blotched over with mildew. Powdery mildew is a fungal disease. It is a disease that can directly effect yields. As the plant is attacked it has to use vital energy to fight the disease and less plant energy is directed to the fruits and flowers. Powdery mildew is found indoors in crowded grow areas where the plants have less than the desirable amount of air circulation. As the plants transpire and release water into the air the room can get very humid quickly. Good climate control practices allow for vent fans to refresh the room with outside air that is run through a HEPA filter prior to entering the room. This is generally controlled by a temperature/humidity controller that can be adjusted to the exacting needs of your individual plants. Most plants like a humidity of around fifty percent when they are blooming. When humidity and temperatures are high powdery mildew has a better chance of starting to grow so really dial in that climate control and you will reap the benefit of less fungal attacks indoors.

If you are reading this because you already have powdery mildew the thing that you have to is decide how far along they are into flowering to see if they can still be treated. Many people follow the theory that if a plant or a flower is in bloom and you treat it for powdery mildew that sometimes you can impart a bad flavor into your plants. The farther you are away from harvesting the better for this reason. How far you vaporize into bloom is ultimately up to you and your taste buds. One of the best ways to treat powdery mildew indoors is by a method called sulfur vaporization. A sulfur vaporizer can be purchased and this apparatus will heat powdered sulfur to a point that is turns into a vapor and covers the room. This process raises the pH level on the plants surface and can effectively stop powdery mildew in its tracks. When you run a sulfur vaporizer it is important to turn off all ventilation and equipment that has compressors because there have been stories of explosions due to having equipment cycle with too much sulfur vapor in the air. A good dosing of a couple of hours a night for two to three nights will generally do the job. If you have a heavy infestation you may need more. Another common way to treat powdery mildew is with a baking soda also know as sodium bicarbonate. I have seen people use concentrations ranging from one to two ounces per gallon in a spray form and some people will also add a small amount of dish soap to act as a surfactant to more evenly cover the plants surfaces. Treat once a week until the powdery mildew disappears. The baking soda method works for outdoors since you cannot treat outdoor plants very easily with a sulfur vaporizer. If you have any questions or comments please contact Troy at troy@ahigheryield.com