Deficiency symptoms
Symptoms of deficiencies range from failure of buds to shoot, terminal stoppage (zinc or copper), poor leaf size (zinc), leaf rosetting (zinc), yellowing between the leaf veins (zinc or manganese) or around the margins of leaves (manganese and magnesium).
A common general effect on young trees is reduced shoot growth or stunted leader growth with multiple shooting from the base of the tree. On bearing trees, canopy growth and yields may be seriously affected.
Zinc
Zinc deficiency can result in dieback of leaders or shortened internodes and small leaves ('little leaf') at shoot extremities, resulting in a bushy or 'rosette' appearance to shoot tips. Other symptoms include the delay or even failure of buds to shoot and early defoliation. The reduced size of leaves is usually associated with bright yellowing between the veins, known as interveinal chlorosis. Affected leaves are more pointed than normal. Low zinc uptake may reduce tree health and yields, even though there are no obvious visual symptoms.
Copper
Copper deficiency can be a major problem with establishment of young trees. It is readily recognisable by speckling of leaves on shoot tips and, in extremely deficient cases, by the cessation of terminal shoot growth resulting in a condition known as 'wither tip'.
Affected young shoots bend down readily, shrivel and die. New shoots emerge lower in the tree, producing a 'witch's broom' appearance at the regrowth point.
Manganese
Manganese deficiency is typically seen as pale areas on the leaf between darker green veins. The interveinal colour is pale green rather than bright yellow as with zinc. Affected leaves are usually the older, most shaded leaves on fruiting spurs. Leaf shape remains normal. Manganese deficiency may be found in most fruit growing districts.
Manganese availability is increased in highly acidic soils and under waterlogged soil conditions. Symptoms may include necrotic spots, or measles, on (or under) the bark. This may be associated with poor growth, or even dieback in severe cases.
Magnesium
Magnesium deficiency produces a distinct yellowing of the leaf tip and margin with a characteristic, dark green arrow tip effect, showing from the leaf base. With severe deficiency, marginal leaf scorch can also occur. The deficiency is most commonly seen on older leaves. Young, vigorous trees exhibit the symptom in the middle to the end of the season.
