Conclusions 



These studies have shown that Liberty is an 

 apple which ripens in late September at a time 

 similar to Empire. A starch-iodine test will be 

 necessary to assess maturity accurately. Due to 



a high sensitivity to chilling injury, Liberty fruit 

 did not store well. This sensitivity may mean 

 that Liberty fruit will have to be stored at higher 

 than normal temperatures if they are to be kept 

 for extended periods of time. 



%1* %£• *t# *f* *f* 



rf* *|^ • r f* •(£• •$• 



Seasonal Light Requirements in a 

 Fruit Orchard 



James T. Williams 



Cooperative Extension, University of Massachusetts 



Shading within a fruit tree can have many 

 effects on tree productivity and fruit quality. 

 Among the factors it influences are fruit set, 

 weight, color, and taste. Therefore, growers 

 need to be aware of its importance, and of the 

 many ways in which they can influence the 

 amount of shading that occurs. 



A number of excellent studies of shading 

 have been published in recent years, and this 

 article will summarize the findings from several 

 of these: Jackson, J. E. and J. W. Palmer, 1977. 

 J. Hort. Sci. 52:253-266; Robinson, T. L., E. J. 

 Seeley, and B. H. Barritt. 1983. J. Amer. Soc. 

 Hort. Sci. 108:855-861; and Rom, C. R. and B. H. 

 Barritt. 1989. pp. 42-57. In Intensive 

 Orcharding. Goodfruit Grower, Yakima, WA. 



Shading has different effects at different 

 times of the year. This fact is illustrated in Table 

 1, which shows results when Redspur Delicious 

 apple trees were shaded to the same extent at 

 three different stages of fruit development. 



During the time of cell division (0 to 47 days 

 after petal fall) shading reduced fruit set by 

 nearly 50 percent. This reduction was not com- 

 pensated by increased fruit size, so fruit yield 



(total weight) was also reduced by about 50 

 percent. Shading during this period, however, 

 had little effect on quality of the fruit at harvest. 



Shading in mid-season (47 to 93 days after 

 petal fall) or late-season (93 to 140 days after 

 petal fall) had no effect on fruit set, but reduced 

 average fruit weight, fruit color, and soluble 

 solids (sugar) content. Early-season shading 

 may have delayed fruit maturation, as judged 

 by starch rating, but mid- and late-season shad- 

 ing appeared to have no effect. 



The effects of shading will depend in part on 

 how much light is available. Under cloudy 

 conditions, effects may be greater than under 

 bright, sunny conditions. However, growers 

 need to manage whatever light is available 

 under their conditions, and there are a number 

 of horticultural practices that can be used to do 

 this. The following suggestions are derived from 

 the studies cited above, some of which are de- 

 scribed in an earlier report [Fruit Notes 55(4):8]. 



1. When fruit spurs are shaded anytime 

 from bud-break until June drop, fruit set 

 will be reduced. Dormant pruning must be 



20 



Fruit Notes, Summer, 1991 



