HARVEST PRESSURES AFFECT FORCED SUMMER ASPARAGUS YIELD IN COASTAL SOUTH-CAROLINA

The purpose of this study was to investigate the effect of different cutting pressures (CP) of 3, 6, 9, or 12 spears per plant on ''UC 157 F-1'' asparagus yield harvested in spring or forced in July or August. Ten-week-old seedlings were field planted in March, 1987 and forced to emerge from 1989 to 1993 by mowing fern in separate replicated plots in July or August. Forcing treatments were not spring-harvested. Harvesting was terminated if 1) 30 harvests had occurred or 2) 80% of all plants reached cutting pressure treatment levels before 30 harvests occurred. Forced yields were compared to normal spring harvests. Normal emergence time is from January to March. CP treatments affected yield more than harvest time Car) during the first three harvest Sears, but, thereafter, HT treatments affected yield more than CP. The most productive HT/CP treatment combinations varied by harvest year as follows: 1989 -spring at 9 to 12 spears per plant, July at 12 spears per pi ant, and August at 9 spears per plant; 1990 -forcing in July or August at 12 spears per plant; 1991 -forcing in July at 9 to 12 spears per plant; 1992 -forcing in July or August at 9 to 12 spears; and 1993 -forcing in August at 9 to 12 spears per plant. Total cumulative yields over the 5 year period were highest with forcing in July at 12 spears per plant and August at 9 spears per plant. The productive lifespan of spring-harvested ''UC 157 F-1'' was only three years because of greater stand loss compared to summer forcing.