Crepe myrtle

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The white powdery stuff on your crepe myrtle leaves is almost certainly powdery mildew, a common fungal disease that affects crepe myrtles, especially in humid climates like Louisiana. You’re also recalling a traditional method used to manage fungal issues: applying a Bordeaux mixture or lime-sulfur paste to the trunk. Here’s a breakdown: ?

? Immediate Action: Treat the Powdery Mildew 1. Prune for Airflow • Trim crowded branches to increase air circulation and reduce humidity around leaves. 2. Apply a Fungicide Use a fungicide labeled for powdery mildew. Common effective ingredients: • Neem oil • Potassium bicarbonate • Sulfur-based sprays • Horticultural oils Apply in the early morning or late evening to avoid burning leaves. ?

?? What You Might Remember: Trunk Paste You’re likely thinking of a lime-sulfur paste or Bordeaux mixture (copper sulfate + lime), painted on the lower trunk to prevent fungal spores from overwintering and reinfecting the tree the following season. How to Make Bordeaux Mixture (Classic Recipe) (Use with caution — this is more preventative than curative and is used when the tree is dormant) Ingredients: • 1 gallon water • 4 tsp copper sulfate (bluestone) • 4 tsp hydrated lime (garden lime) Instructions:

1. Mix copper sulfate in ½ gallon of warm water.
2. Mix hydrated lime in another ½ gallon of water.
3. Combine the two mixtures, stirring constantly.
4. Apply with a brush to the lower 12–18 inches of trunk when the tree is dormant (late fall or early spring).
Note: Do not apply Bordeaux mix during active growing season—it can burn foliage. ?

?? Natural Alternative (for Leaves): A simple baking soda spray works well for mild infections: DIY Baking Soda Spray: • 1 tablespoon baking soda • ½ teaspoon dish soap (non-detergent) • 1 gallon water Spray every 7–10 days, especially after rain.

? ?? Long-Term Management • Choose powdery mildew-resistant varieties if planting new crepe myrtles. • Ensure good air circulation and full sun. • Avoid overwatering or fertilizing with high-nitrogen fertilizers (this encourages lush, mildew-prone growth).

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