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RECENT PUBLICATIONS 



You may wish to send for one or more of the following publications: 



1. Fruit Varieties in New York State: Berries. Extension Bul- 

 . letin 1167. 



2. Fruit Varieties in New York State: Apricots. Extension Bul- 

 letin 1168. 



3. Raspberry growing in New York State. Extension Bulletin 1170. 



i+. Combating Replant Problems in Orchards. Extension Bulletin 

 1169. 



All these publications are available from the Cooperative Extension 

 Service, Cornell University, Ithaca, New York. 



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ZINC LEVELS IN MASSACHUSETTS APPLE ORCHARDS 



W.J. Lord, Bertram Gersten and J.H. Baker 

 University of Massachusetts 



Zinc deficiency in apple orchards has been considered a problem in 

 western United States for many years, but only recently has it been of 

 concern in New England. In 1965, Stiles and Goff in Maine presented 

 data showing a relationship between zinc level and yield of Mcintosh 

 and suggested that this element may affect tree growth, limit yields, 

 and affect fruit color development. Siles reported that 35 Mcintosh 

 leaf samples from Maine apple orchards in 19614- averaged only 8.0 ppm 

 zinc. Since these orchards were considered to be highly deficient in 

 zinc, a tentative optimum standard of 37.5 ppm has been suggested by 

 Stiles. In contrast to these results, a block of Mcintosh trees in cen- 

 tral Massachusetts with a record of high yield (average yield in 1961 

 and 1962 was 50 bushels per tree per year) were found to contain only 

 10-12 ppm of zinc. These trees, though well below the proposed optimum 

 levels for zinc, show no signs of zinc deficiency. 



Critical level of a nutrient is the level above which a plant is 

 amply supplied and below which it is deficient in that element. A crit - 

 ical level for zinc in apple leaves is difficult to establish from lit- 

 erature. Chandler et al. in 1934 reported ^--S^- ppm zinc in deficient 

 apple leaves in California orchards and 4-80 ppm in healthy leaves. 

 Thomas et al . in 1949 found 14-65 ppm zinc in healthy young apple trees 

 in Pennsylvania. In 1964, Uriu and Koch in California suggested that 

 13-14 ppm could be the borderline between zinc deficient and zinc suffi- 

 cient levels. Heeney et al . , in 1964, also suggested a critical level 

 of 15 ppm of zinc for eastern Ontario. 



