Is neem oil effective against white spots?
Written by
Nguyen Minh
Reviewed by
Prof. Charles Hartman, Ph.D.Neem oil attacks the life cycle of pests and fungi which cause white spots. I have saved basil crops from powdery mildew with a weekly spraying approach. This is a natural extract that works best when applied before the problem manifests. Once the spots begin to spread, neat oil can be combined with pruning to ensure all spots are eliminated.
Effective Targets
- Powdery mildew spores on leaf surfaces
- Spider mites hiding under leaves
- Aphid colonies near new growth
Application Basics
- Mix 2 tbsp cold-pressed neem per gallon
- Spray at dawn or dusk to avoid leaf burn
- Reapply after heavy rain
Safety Protocols
- Test on 2 leaves before full treatment
- Avoid spraying flowering herbs (alters taste)
- Keep away from ponds (toxic to fish)
Morning treatments provide enough time for leaves to dry before nightfall. I spray with neem on Tuesday mornings to be able to check for any pests over the weekend. If you have a heavy infestation, mix in ½ teaspoon of castile soap. It helps the oil stick to the plant and pest. Be sure not to spray it on already-stressed plants during a heat spell.
Prevent resistance to these materials by rotating neem with potassium bicarbonate sprays. After 8 weeks of neem-only treatments, this client's bush started to show signs of tolerance. Hormones break down potency through regular use. Alternate each treatment after three applications. I saw a 70% drop in reinfection rates in my trials with this strategy.
After applying neem to your plants, make sure to monitor your plants for 48 hours. You should expect to see healthy leaves darkening a little. If you notice the yellowing of leaves, you have probably overdosed on the neem. Flush the soil out with two gallons of water. Your vigilance will help ensure Neem will be a garden ally, not a threat. Those white spots will not know what hit them!
Read the full article: White Leaf Spots: Causes and Solutions
