Foliar spray for small trees and shrubs is best applied under which leaf condition?

• A. When leaves are fully spread and until fall turns them colorful
• B. Before leaves unfurl completely in spring
• C. After fruit set
• D. During drought conditions

Answer: (A)

Foliar sprays are absorbed best when the leaf surface is fully expanded and the plant is actively growing. At this stage the leaves present the largest contact area, the cuticle and stomata are functioning, and the spray can spread evenly and be absorbed more effectively. If leaves are not yet fully opened, the surface is uneven and tender, which can lead to uneven coverage or even leaf injury. Once leaves start turning color in the fall, they’re beginning to senesce, absorption declines, and the spray is more likely to run off or be degraded. Drought stresses the plant and can alter leaf conditions in a way that reduces uptake and increases injury risk. So the best time is when leaves are fully spread and still green, prior to fall color development.