m 



fertilization of ovules to increase fruit set, and to supplement, 

 or replace a part of soil applications of nitrogen. Low N status 

 of the flower buds and/or low temperatures during the pollination 

 and fertilization period lead to more rapid degeneration of the 

 ovules. Conversely, high temperatures and/or high N status can 

 delay this degeneration and allow a longer period of time for 

 fertilization to be completed. 



To acheive this situation, urea sprays can be applied at the 

 rate of 3 lbs/100 gallons dilute rate in the pink spray and/or 

 5 lbs/100 gallons dilute rate in the petal fall spray. This 

 approach should be considered whenever the preceding season's leaf 

 samples indicate a leaf N content of less than 2.2 percent. Used 

 in this manner, the amount of actual N applied per acre will range 

 from approximately 3 lbs on close trellis plantings to 16 lbs on 

 large standard trees. 



The foliar sprays of urea are not suggested for use on pear, 

 peach, or cherry trees because they do not absorb and utilize urea 

 as efficiently as apple trees. 



Magnesi um (^1g) . Foliar sprays of Mg sulfate (Epsom salts, tech- 

 nical grade) have been used to overcome temporary deficiency of 

 Mg in a number of fruits. These sprays are most effective if 

 applied soon after bloom while foliage is capable of absorbing the 

 material. With apples, the usual suggestion is to apply 15 lbs. 

 of Epsom salts per 100 gallons (dilute rate) in the petal fall, 

 first and second cover sprays. Epsom salts is compatible with 

 most pesticides up to 15X concentrate (225 lbs. per 100 gallons 

 of tank mix) . Young rapidly growing trees may require additional 

 applications to provide adequate amounts of Mg . 



Mg chelates (EDTA ) are available in liquid or powdered formulations 

 Because of greater efficiency in correcting deficiencies, the 

 chelates are used at lower rates (i.e. 1 lb . or 1 qt. per 100 

 gallons) and may be more amenable to use in concentrate appli- 

 cations . 



Corrective treatments for Mg deficiency must be considered in 

 terms of both soil and foliar applications. In a preventive pro- 

 gram, suggested combinations might include the following: 



Leaf 



Mg (% dry wt.) Magnesium treatment 



0.30 to 0.45 Continue present program. 

 (Satisfactory) 



0.20 to 0.30 Apply dolomitic lime if pH is below 6.5, plus 



(Low) 600 lbs. of Sulpomag per acre if K level is not 



excessive, plus three sprays of Epsom salts or 



below 0.20 equivalent Mg treatment. 



(Deficient) 



