Preventing Fruit on Ornamental Plum Trees

Chemical Thinning Options

To stop an ornamental plum from producing messy fruit, apply a growth regulator shortly after petal fall:

• Gibberellic acid (GA₃) – applied about 1 week after petal fall.
• Naphthalene acetic acid (NAA) – a more complete thinner, same timing.

Both are plant hormones, not restricted-use pesticides. Use a heavier concentration than for fruit thinning to eliminate the crop entirely. Always follow label rates and timing.

Reference: UMass Fruit Advisor – Thinning (apple guidelines adaptable to plums).