Deficiency due to inadequate N fertilization and/or ineffective N fertilization. No additional N fertilizer should be applied until next spring. When N leaf level is greater than 2.4%, possible fruit disorder may occur. If N is low, for next year's crop, apply 0.30-0.60 pounds N per tree. If this year's terminal growth was less than 8 inches on trees that set a good crop, use the higher N rate; if terminal growth was 8 inches or more, lower the rate of N. Where vigor is low, N can also be supplied by spraying low biuret urea at 6 to 12 pounds N per acre after bloom but not in late cover sprays. If N is within the sufficiency range, or slightly high, for next year's crop, apply 0 to 0.60 pounds N per tree. If this year's terminal growth was less than 8 inches on trees that set a good crop, use the higher N rate; if terminal growth was 8 inches or more, lower the rate of N. If terminal growth was greater than 15 inches, do not apply any nitrogen.

Deficiency is generally due to low soil test P. Low P in leaves can also be due in part to a low soil pH. For best P availability, maintain soil pH between 6.0 to 6.5. If the leaf level is less than 0.15% and the soil test P level is also low, for next year's crop, apply 60 pounds P₂O₅ per acre. If the soil test P level is medium, apply 30 pounds P₂O₅ per acre; if the soil test level is high, do not apply additional phosphorus fertilizer next year. If the leaf P level is within the sufficiency range, no additional phosphorus fertilizer will be required for the next crop, irrespective of the soil test P level.

Deficiency is due to low soil test K. Do not apply excessive K or more than recommended rates of K fertilizer as Mg deficiency may result. If leaf and soil K levels are both low, for next year's crop, apply 60 pounds K₂O per acre. If leaf K levels are low and the soil test K levels are medium or higher, do not apply additional K₂O. If the K content is within the sufficiency range, no additional potassium fertilizer will be required for the next crop, irrespective of the soil test K level.

Low Ca leaf levels will result in poor fruit quality and a physiological disorder called "Bitter pit" in apple. If the Ca level in apple tissue is less than 1.0%, apply calcium chloride at 2 pounds per 100 gallons (maximum of 3 to 6 pounds per acre) or calcium nitrate at 3 pounds per 100 gallons (maximum 4.5 to 9.0 pounds per acre) in all cover sprays. Higher rates can cause foliage burn and should not be re-applied unless at least 1/2 inch of rain has fallen since previous application. Do not apply foliar sprays when temperatures exceed 90°F. Since apple acts as a low accumulator of Ca, take care to ensure the soil pH is adequate and the other elements are applied in their proper amounts. In some cases, supplemental application of Ca to the soil as gypsum or the use of calcium nitrate to supply the N requirements may be desirable.

Deficiency is generally due to low soil pH and /or low soil test Mg. If soil pH is less than 6, follow recommendations for application of dolomitic limestone from a soil test. If soil pH is 6 or higher and Mg is low, soil apply 20 pounds of Mg per acre as magnesium sulfate (Epsom Salts). To get a quick response, Epsom Salts may be included in normal pesticide applications by adding 15 pounds of Epsom Salts per 100 gallons of water in the petal fall, first cover and second cover sprays.

Deficiency is not a common problem while excessive Mn is frequently a problem. Low subsoil pH (or surface soil pH) results in the uptake of large quantities of Mn and produces a physiological disorder in apple called "measles."

Deficiency not a problem in Georgia. High Fe test results normally indicate soil or dust contamination. An accurate Fe determination can only be obtained with washed leaves. (See section - Washing to Remove Contaminates)

Deficiency is a common problem with apple resulting in physiological disorder called "Internal Cork." Boron deficiencies can be corrected by applying foliar applications of B, using 0.2 to 0.4 pounds of B/100 gallons (0.4 to 0.8 pounds per acre) at both petal fall and first spray. CAUTION: Do not exceed the recommended rate as excessive B may cause injury or death to trees. If the B content is within the sufficiency range, apply a maintenance application of B using 0.2 to 0.4 pounds of B/100 gallons (0.4 to 0.8 pounds B per acre) at petal-fall spray.

Deficiency is not likely to occur.

Deficiency is not an uncommon problem resulting in small fruit size and lack of good fruit color. For corrective treatment, apply a foliar application of Zn in mid-October using 3 pounds of zinc sulfate per acre in 100 or more gallons of water per acre.

High Al levels are not likely to occur. When both high Fe and Al values are obtained, probably due to soil or dust contamination. See Fe discussion above.

Sufficiency range is not firmly established for apples.