Mechanical pruning of lemon trees leaves stubs around which buds sprout, producing vegetative growth which is usually unwanted. Hand pruning, which selectively removes unwanted limbs, does not cause as many buds to sprout, since pruning cuts are usually made at laterals. However, pruning of any kind causes a vegetative growth flush, and an immediate reduction in yield. On mature trees it would be of economic benefit on some occasions to stop, or at least reduce, this growth flush. Removal of trunk sprouts is important especially during the formative years, or if high scaffold limbs are desired.

C. B. Cree, Department of Plant Sciences, UCR, supplied the statistical analysis. Dr. I. A. Rammer of FMC, Niagara Chemical Division supplied the chemicals, and Kaiser-Aetna provided the trees and care of the orchard.