-2- 



Experlments in ivlassachusetts have sho',m that magnesium deficiency in blue- 

 berries can be corrected by soil application of high magnesium lime or Epsom salts. 

 Depending on acidity a ton to a ton and a half of dolomitic limestone per acre 

 is usually enough. Or one can use 150 pounds of Epsom salts per acre. 



There are tv/o other vrays by vrhich magnesium deficiency in blueberries might 

 be corrected. Epsom salts might be sprayed on the leaves as is done rd-th apples. 

 A special form of magnesium called chelated (pronounced key-late-ed) magnesium 

 might be applied to the soil. Both of these methods were tried. The results 

 were measured by determining the magnesium content of leaves from treated and 

 untreated plants before and after treatment. The results are given: in the foil cav- 

 ing table : . ■ 



Percent Magnesium in Blueberry Leaves - Dry weight basis 



Epsom salt 

 Spray 



Check 



Chelated Magnesium per bash in ounces 



T 



IF 



Before 



After 



.oU 

 .07 



.07 

 ,10 



.06 

 .09 



.06 

 .06 



.08 

 .11 



.08 

 .11 



The magnesium content of the unsprayed check leaves increased just as much 

 as that of the Epsom salt sprayed leaves. I^he blueberry leaves are so waxy that 

 it is not surprising the spray applications were not effective. 



Chelated compounds are formed by combining a metal, such as iron or magnesium, 

 with an organic compound in such a v/ay that the metal is more readily absorbed by 

 plants. Chelated iron compounds have been very successful in correcting iron 

 deficiency in citrus and some other crops. It seemed that chelated magnesium might 

 be successful in correcting magnesium deficiency in cultivated blueberries. Evi- 

 dently this is not the case. The data in the table shows that even a pound per 

 bush of chelated magnesium increased the magnesium content of leaves no more than 

 that of unsprayed leaves. 



Soil applications of Epsom salts or dolomitic limestone are still the best 

 materials for correcting magnesium deficiency in blueberries, 



J. S. Bailey and Bertram Gersten 



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OBSERVATIONS IN CALIFORNIA 



In a state such as California, which produces a vri.de range of deciduous 

 tree fruit crops under variable soil and climatic conditions, one xirould expect 

 growers to have a great number of production and marketing problems. One of 

 their common production problems is oversetting of fruit. As you know fruit thin- 

 ning of apples and peaches are problems of eastern grovrers. 'Te are attempting to 



