The relationship between soil tests, tissue tests and response of fruit trees to K fertilizer has not been adequately determined. K is strongly sorbed by soil components and thus is not readily mobile in soils. Leaf analysis in conjunction with soil testing of samples collected from both the topsoil and subsoil provides the best estimate of the amounts of potassium that are available for uptake by fruit trees. Older leaves are affected first. Leaf scorch will show up first.
Some species show a recurving of petioles along with upward rolling of leaf blades.
Necrotic speckling and scorching of leaves is also common. Shoots are slender and spurs are weak. Fruit may hang on tree after leaf fall. Time of fruit maturation is delayed.