Fact Sheet No. 228, UMaine Extension No. 2239 Prepared by Tom DeGomez, Extension Blueberry Specialist, and Dr. John Smagula, Professor of Horticulture, The University of Maine, Orono, ME 04469.  March 1990. Introduction One of the most obvious factors affecting the yield of a blueberry field is the presence or absence of blueberry plants. Fields are