Submitted to: Annual Cumberland Shenandoah Fruit Workers Conference
Publication Type: Proceedings
Publication Acceptance Date: July 11, 2002
Publication Date: N/A
Interpretive Summary: The importance of light in the growth and production of apple is well documented. However, much of an apple tree's canopy may be enveloped in shade during the day. Shade reduces fruit bud formation, affects leaf structure and photosynthesis, and results in lower fruit quality. The objective of this study was to examine the effect of constant shade (24 hrs per day) or periodic shade (3 or 6.5 hrs per day), applied on a daily basis, on growth and fruiting in dwarf apple trees. Constant shade at 73% reduced trunk diameter, bloom clusters, and yields, but increased shoot extension growth. Periodic shade had little or no effect on growth, but did show a cumulative effect over years on bloom and yield. Shade applied in the morning had more of an effect than shade applied after 1330 hours. This information is useful to extension fruit specialists and fruit growers in training and pruning apple trees, and to researchers designing light and dshade studies.
Technical Abstract: Third leaf 'Ginger Gold'/M.9 apple trees were covered with 73% shade cloth on a continuous (CS) basis from mid- or late May through September beginning in 1998 and continuing through 2001. An additional group of trees received 73% (1998-1999) or 95% (2000-2001) shade (PS) for a period of 3 hrs (1998-2000) or 6.5 hrs (2001) each day from May through September. .The initial season of CS reduced trunk diameter; in subsequent years, trun growth for CS trees was equal to or less than that of check (C) trees. PS applied from 0800-1100 HR reduced trunk diameter after one and two years, but not in the third and fourth years. Shoot growth was increased by CS, but not by PS. Bloom was reduced after one year of CS. In subsequent years there was a trend for reduced bloom from CS, but differences were not significant. Bloom was reduced after two seasons of PS. These trees returned bloom the following year. Both CS and PS treatments reduced fruit tnumbers at harvest and yield efficiency. Whole tree shade ( 73% or 95%) reduced canopy temperature and incident photosynthetic photon flux. Results indicated that trees can respond to and recover from CS in one growing season.