EFFECT OF PRIMOCANE SUPPRESSION DATE ON MARION TRAILING BLACKBERRY .1. YIELD COMPONENTS

Primocanes of ''Marion'' trailing blackberry plants (Rubus spp,) were suppressed by cutting them off at ground level in either late April, M ay, June, or July 1991 and 1992, A control was included in which primo canes were not cut, Four canes per plant were trained in either August or February, with all other canes being removed and measured, Yield d ata were collected in 1992 and 1993, after which yield components were measured, Cane diameter was greatest for unsuppressed plants and decl ined with later primocane removal date, Cane length was greatest for u nsuppressed and April-suppressed plants, Internode length decreased an d main cane percent budbreak increased with later suppression date, Ca ne number and total main cane length per plant were increased in April -, May-, and June-suppressed plants in 1992 and for April- and June-su ppressed plants in 1993, Consequently, yield of April-suppressed plant s exceeded that of unsuppressed plants in 1992, Yield of April-, May-, and June-suppressed plants exceeded that of unsuppressed plants in 19 93, August-trained plants yielded 46% more than February-trained plant s, primarily because of higher percent budbreak on main canes. August- trained plants also produced longer canes with more nodes and a greate r number of fruit per main cane lateral.