Powdery mildew is one of the most common plant diseases. It is a fungal disease caused by Erysiphales fungi that affects a wide variety of host plants including ornamentals, grasses, crops, shrubs, trees, and weeds. Luckily, powdery mildew is generally easy to identify, it is not typically fatal for the plant, and it can be treated with some simple tools and perseverance.

An interesting fact about powdery mildew – Powdery mildew fungi are host specific. This means different powdery mildew fungi infect different plants. The powdery mildew on your roses may infect other roses but will not spread to any other plant nearby. However, all powdery mildews favor the same humid conditions.

Identifying Powdery Mildew

Powdery mildew is not too difficult to spot. It appears in the form of whitish or grayish patches on plant leaves or stems. The appearance of the patches could be described similarly to talcum powder or powdered sugar.

Preventing Powdery Mildew

Powdery mildew favors high humidity, young plants, succulents, and crowded conditions. The best way to prevent powdery mildew is to keep conditions unfavorable for it. Do this by reducing crowding of plants and reducing humidity when possible. Choose where to plant your younger or more susceptible plants wisely: give them plenty of space, and don’t plant in direct shade if possible. Water plants at the ground to reduce moisture around the leaves and stems. Keep airflow high with pruning and thinning of plants as they grow.

Treating Powdery Mildew

One option for treating powdery mildew if you catch it early is by simply removing the affected parts of your plant. As a follow-up for this, keep a close watch for more of the disease spreading and be sure to reduce humidity and create more airflow for your affected plant. Avoiding fertilizer during this time is also a good idea. This is because fertilizer on growing plants will subsequently increase the mildew’s spread as well.

Removing the affected parts of the plant is generally your best bet since the mildew can spread quickly once it is established. Another option for continuing the treatment is by using a fungicide. Or creating a homemade one with baking soda, soap, and water mixture. Mix 1 tbsp baking soda, 1/2 tsp liquid soap, and 1 gallon of water to create the mixture. Spray the affected plant(s) once every 1-2 weeks with your fungicide for continual protection against the disease returning.

If you liked this blog be sure to read more about the different types of botany – including plant pathology! – in my blog about the most interesting branches in botany. Also check out my blog on the best time to plant your garden.