Neem plants (Azadirachta indica) are broadleaf evergreens growing in U.S. Department of Agriculture plant hardiness zones 10 through 12. These tropical trees produce fragrant white flowers, and the oil derived from their leaves is used in pesticides to control insects and diseases that affect plants. Even though it has no serious problems, scales sometimes can infest the neem tree, consuming the plant’s cell content. Their feeding causes the foliage of the infested tree to wilt and discolor, and the leaves can drop from the branches prematurely. Thankfully, you can eliminate scales by implementing proper cultural care used in conjunction with horticultural oil.
Things You'll Need
- Annual plants, such as basil, dill and sweet alyssum
- Work gloves
- Pruning shears
- Horticultural oil concentrate
- Stir stick
- Garden sprayer
Attract lacewings, ladybugs and other beneficial insects that prey on scales by planting annual plants, such as basil (Ocimum basilicum), dill (Anethum graveolens) and sweet alyssum (Lobularia maritima).
Wear work gloves. Prune heavily infested branches off the neem tree with a pair of sharp and sanitized pruning shears. Dispose of the infested branches immediately.
Dilute 5 tablespoons of horticultural oil concentrate in 1 gallon of water, mixing for several seconds with a stir stick. Pour the diluted oil into a garden sprayer. Spray the infested neem tree, covering the underside and topside of the leaves, trunk and branches. Repeat the process only if needed 30 days after the initial treatment.
Tips & Warnings
- Follow the mixing and application instructions found on the horticultural oil label for best results.
- Use horticultural oil only when temperatures fall between 40 and 90 degrees, the wind is calm and rain isn't forecast for 24 or more hours.
- Provide proper irrigation to help keep neem trees healthy and vigorous, which increases its chance of withstanding a scale infestation with little to no long-term damage.
- Wear chemical-resistant rubber gloves when using horticultural oil.
- Keep people and pets away from the treated area until the horticultural oil has dried.
- Avoid treating drought-stressed plants with horticultural oil.
- Avoid treating plants when bees are actively present.