Getting Rid of Powdery Mildew

A cloudy afternoon is always a welcomed event during the heat of summer, but when dealt an extended stay of steady cloud cover, garden problems can begin to arise. Besides the lack of direct sunlight, the cooler and humid environment brought forth with cloud cover provides a catalyst for the growth of pesky Powdery Mildew. This parasitic family of fungi is known to attack a variety of garden plants including, but not limited to, squashes, tomatoes, onions, grapes, berries, shrubs and some fruit trees. At first, powdery mildew may only show up as a few fuzzy white splotches on lower foliage, but it can quickly manifest into a much larger problem. Luckily, getting rid of powdery mildew organically is quite easy. Keep reading to find out how!

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What is Powdery Mildew?

When speaking of powdery mildew, one is actually referring to a wide range of fungi species, all of which belong to the Erysiphales order. The individual species may attack different host plants, but they always show up the same way. Growing on both the upper and undersides of infected foliage, the fungi feeds off of epidermal cells. Spreading quickly in lower foliage, powdery mildew infections can spread to all parts of a plant. The infection is characterized as a splotchy white/grey growth that can cause leaf chlorosis and drastic losses in yields. Powdery mildew effectively reduces photosynthetic surface area on the foliage, causing stunted or slow growth. 

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Controlling Powdery Mildew - 

There's a few chemical pesticides that work to eliminate powdery mildew, but honestly, they're not needed. Good gardening practices and a simple organic control will keep your plants healthy and mildew free!

Diluted Milk Spray for getting rid
of Powdery Mildew. 

• Isolate - For container gardeners who are able to move their plants, isolate infected individuals from similar species. If isolation is not possible, keep an extra eye on nearby plants. 

• Avoid Excess Nitrogen - Nitrogen is essential for plant growth, but too much can lead to overly dense foliage. When foliage is too thick, it promotes a humid and poorly ventilated micro-climate. This allows powdery mildew to grow and spread rapidly.

• Increase Ventilation - When a powdery mildew infection is present, increasing the ventilation between leaves can greatly reduce the fungi from spreading. This process entails removing older and diseased leaves in a way that will allow for greater airflow. Generally, if a leaf or branch is more than 50% infected with powdery mildew growth, trim it off and throw it away. 

Close up of Powdery Mildew on
a Summer Squash Leaf. 

• Milk - Nobody knows quite sure why it works, but a foliar spray consisting of just milk and water can eliminate powdery mildew infections. To prepare the spray, mix milk with water in a 1:10 ratio. Add the diluted milk mixture to a spray bottle and thoroughly mist the entire canopy (both upper and undersides of foliage). Apply up to two times weekly during the morning hours. The milk mixture should be administered at the first signs of powdery mildew and continued until there is no more fungal growth. 

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Getting rid of powdery mildew can take up to a few weeks time, and a whole lot of your patience! When this annoying pest finally resides, you'll be exuberant. Utilize a diluted milk regimen and practice good gardening routines to control powdery mildew. Thanks for reading.