Apple Tree Spray Schedule: Petal Fall to Harvest

You haven't sprayed since dormant season, and now it's petal fall with cold temperatures. You're asking about gibberellic acid and what to apply.

Recommended Spray Program

• Petal fall: Sulfur + BT (Bacillus thuringiensis) for disease and caterpillar control. Repeat in 7–10 days.
• Start weekly kaolin clay sprays at petal fall—deters many insects and reduces heat stress.
• At fruit set: Sulfur or Bordeaux mixture if disease signs appear; repeat every 14 days. Add pyrethrum or other organic insecticide for pests; also every 14 days.
• Stop all sprays 30 days before expected harvest.

On Gibberellic Acid

Not recommended for routine use. It's a growth regulator used commercially for specific purposes (e.g., reducing russeting, improving shape), not a general "strengthener." Focus on the core program above.

Cold weather during bloom can reduce pollination and fruit set—kaolin clay helps moderate temperature extremes. Stick to the schedule for clean, healthy apples.