Agriculture Reference
In-Depth Information
Potassium (K) Deficiency
Symptoms.
Potassium deficiency in tree fruits typically appears as
necrotic (dead) leaf margins and brownish-yellow spots on the leaf
blades, starting with older leaves. Leaves may take on a bronzed ap-
pearance. Spurs and new shoots may exhibit weak growth and early
defoliation. Fruits may be small, poorly colored, and lacking in acidity.
Potassium-deficient trees fail to properly develop cold hardiness.
Treatment.
Apply 400 lb/A (15 oz/100 square feet) of sul-po-mag or
160 lb/A (6 oz/100 square feet) of potassium sulfate. Apply when
symptoms develop. Potassium should normally be applied during early
spring or late fall.
Calcium (Ca) Deficiency
Symptoms.
Calcium deficiencies seldom appear in leaves, although
root and shoot growth can be reduced and leaf tips scorched. Symp-
toms are more often seen as fruit disorders, such as bitter pit, cork
spot, and internal breakdown of apples.
Treatment.
Keep soil pH correctly adjusted. Add 1,000 lb/A (2.3
pounds per 100 square feet) of gypsum in spring or whenever symp-
toms develop. Foliar calcium sprays during fruit development may help
reduce bitter pit and cork spot in apples.
