-24- 



this problem. Raising soil pH with calcitic lime may 

 give a partial and temporary improvement in Mg availability 

 but does not correct the basic Mg shortage. Response to 

 soil applications o£ Mg salts may be slow. Inclusion of 

 Epsom salts in the petal fall, first and second cover spray 

 is usually necessary until soil Mg levels are corrected. 

 Epsom salts should be applied at a rate of 45 lbs. per 

 acre in each of these 3 sprays if Mg levels in leaf samples 

 are less than 0.5%. 



B^. Optimum leaf concentrations of B are in the range of 

 35 to 50 ppm. B sprays are effective in meeting fruit 

 requirements and avoiding cork formations and early drop 

 associated with B deficiency. However, B is also nec- 

 essary for root development. Annual applications of B in 

 the fertilizer or applied separately plus foliar sprays 

 may be required to meet the needs of high-producing 

 orchards on size-controlling rootstocks. Using annual 

 soil applications of 1-1/4 to 2 lbs. actual B per acre 

 (equivalent to 6-1/4 to 10 lbs. of a 20% fertilizer grade 

 borate) approximate annual needs but may require 1 or 2 

 foliar sprays of Solubor (total of 2 to 6 lbs. depending 

 on tree size and planting density) to fully meet the 

 boron requirements. 



Zn. Optimum Zn leaf levels are similar to those of B, i.e., 

 '6b to 50 ppm. Leaf concentrations below 15 ppm should be 

 considered deficient. Varieties that accumulate higher 

 levels of P appear to have higher Zn requirements than 

 those that accumulate less P. Annual requirements for 

 Zn are approximately 2 lbs. per acre if applied as inor- 

 ganic salts in dormant sprays or approximately 0.2 to 0.3 

 lbs. of actual Zn applied as foliar sprays of EDTA chelates 

 (3 to 5 lbs. /acre). Amounts of Zn required to correct 

 severe deficiencies may be 4 to 5 times these amounts. 

 Zn-containing fungicides provide some benefit but are not 

 adequate to supply the total need. Leaf samples from 

 trees sprayed with Zn-containing fungicides may contain 

 150 ppm to 500 ppm Zn but most of this is not active. In 

 such cases, P contents of the samples and tree growth and 

 fruiting are usually more indicative of the Zn status. 



Mn . The optimum levels of Mn range from 35 to 50 ppm. 

 Mn deficiency may be associated with high pH conditions, 

 K deficiency, or in some cases may be associated with long- 

 term effects of certain herbicide programs. It is easily 

 supplied by using Mn-containing fungicides in the petal 

 fall, first and second cover sprays, or by applying Man- 

 ganese sulfate (2 to 4 lbs. per 100 gallons dilute rate 

 equivalent) at first cover. Leaf samples from trees 



