ALTERNATIVE ORCHARD GROUNDCOVER MANAGEMENT SYSTEMS AFFECT APPLE QUALITY AND MATURITY INDICES

Alternative groundcover management systems (GMS) beneath establishing 'Jonagold' apple trees have been evaluated since 1986 in an orchard field test Tree-row GMS being studied include post-emergence herbicide (glyphosate) “killed sods”, pre-emergence herbicides (norflurazon and diuron). a crownvetch “living mulch”, hay-straw mulch, monthly cultivation, and a closely mowed sodgrass. Trees in herbicide and straw-mulch plots produced the most fruit in 1990, but in 1991 there were no GMS-related differences in crop load. Fruit were larger in herbicide and straw-mulch plots in 1990 and 1991, and red color development was better in sod and crownvetch GMS. Starch-to-sugar conversion was advanced in apples from sodgrass and straw mulched plots. The ethylene climacteric was delayed in fruit from crownvetch and straw-mulch GMS, and peaked rapidly as mean starch indices approached 4.0 in all GMS treatments. Differences in soil moisture and nutrient availability under alternative GMS may have influenced fruit quality and maturity.