How to Treat Tree Mildew Naturally


Mildew may look horrible on your trees but it isn't likely to cause any serious damage. While it may seem obvious, keeping your tree clean and healthy are your best defenses against mildew infections. Beyond that, simple natural home remedies hold the key to effectively bringing the problem under control---or at least to a point that adheres to your level of tolerance.

Step 1

Examine the leaves of your infected tree for mildew, particularly during the late summer and early fall. This is the time of year that mildew growth is most likely to take place due to warm days followed by cool nights. As the fungal infection progresses, leaf surfaces gradually take on a grayish or whitish cast. Late in the season, little black specks may appear to be scattered on the leaves, too. The tree can be expected to lose leaves, but you shouldn't worry unless a tree loses more than 25 percent of its leaves.

Step 2

Treat your tree with safe and effective homemade fungicide at the first signs of mildew infection. Dissolve 2 tbsp. baking soda in a gallon of warm water. Stir in 1 tsp. horticultural oil or vegetable oil and blend thoroughly. Pour the solution into a repurposed plastic spray bottle and apply directly to the mildew on the tree. Coat all affected surfaces generously. Repeat weekly throughout the growing season thereafter as a maintenance measure. Reapply following rainfall.

Step 3

Feed your tree appropriately during the growing season. Don't overfertilize, which produces succulent new growth that attracts mildew.

Step 4

Water the tree only when necessary, and make sure that the area remains well-drained. Overwatering causes root rot, which will stress the mildewed specimen even further.

Step 5

Prune and thin your tree correctly as necessary to ensure adequate air circulation.

Step 6

Keep the area under and around your tree clean. Rake fallen leaves often. If the plant has an active mildew condition, pick up fallen leaves or raked debris immediately and destroy it. Don't add any of it to your compost heap.

Things You'll Need

  • Baking soda
  • Horticultural or vegetable oil
  • Repurposed plastic spray bottle


  • Washington State University: Powdery Mildew
  • Brooklyn Botanic Garden: Nine Keys to Disease Prevention
  • Go Organic Gardening: Organic Pesticides Guide
  • Pest Control Options: Natural Sprays for Fruit Trees

Who Can Help

  • Bachman's: Preventing Mildew With Horticultural Oil and Soap
Keywords: treat tree mildew, treat mildew naturally, natural mildew treatment

About this Author

Axl J. Amistaadt began as a part-time amateur freelance writer in 1985, turned professional in 2005, and became a full-time writer in 2007. Amistaadt’s major focus is publishing material for GardenGuides. Areas of expertise include home gardening, horticulture, alternative and home remedies, pets, wildlife, handcrafts, cooking, and juvenile science experiments.