An important sign of a deeper lack of nutrients in the visual assessment (so-called visual diagnostic methods) is the place of occurrence of symptoms on the outside of the plant.

If symptoms of deficiency occur in the initial period:
(a) on younger leaves, the plant lacks iron or zinc, copper or boron;
(b) on older leaves, the plant lacks either nitrogen or phosphorus, potassium or
magnesium.

At nitrogen deficiency (N) plants grow poorly, remain small and mature earlier, fruits are small and few. At first the leaves are light green, later even yellow, or even reddish, older leaves often fall off prematurely.

Also at phosphorus deficiency (P) plants lag behind in growth, are small and stunted. The flowers are poorly fertilized, the fruits are difficult to ripen and are acidic. Older leaves are gray-green, partly reddish and fall off prematurely. If the plants suffer from a lack of potassium (K), the water regime is disturbed, so that the leaves, or. whole plants have a withered appearance. The edges of the leaves fade to brown (first in the older ones), the leaf tips sometimes twist inwards. The shoots of the branches near the trees dry out, the fruits are small, do not taste good and are not durable.

At calcium deficiency (Ca) ceases to form root hairs and old roots turn brown, later rotting and dying. The edges of the younger leaves are faded, the older ones are dark green. In particular, stone fruits and shells suffer from glucose and cancer.

Symptoms magnesium deficiency (Mg) are very typical. First, on the older leaves, yellow spots appear between the green veins of the blade next to the dark green ones. Clusters of green chlorophyll resemble beads strung on a string. This mosaic later turns into continuous striped chlorosis (up to necrosis) in monocots and spotted in dicotyledons. In case of severe deficiency, the symptoms also appear on younger leaves.

Sulfur deficiencies (S) are similar to nitrogen. However, light green to yellow are younger leaves at first.

A typical manifestation iron deficiency (Fe) is the so-called chlorosis, ie the leaves are light green to bright yellow at the end of the shoots.

In manganese (Mn) in its absence, light yellow to dark brown spots form between the veins of the blade of the middle to upper leaves. Root growth also lags far behind. These symptoms are especially pronounced in cucumbers.

At boron deficiency (B) the tops of young shoots die off, the young leaves are often curled and brittle. At first they have a dark green to blue-green color, later they fade and die. The flowers do not form or develop. The fruit shows screaming and freckles.

Up to whitish coloring and bottling, or the curvature of the youngest leaves is a manifestation copper deficiency (Cu). Flower formation is also limited. Withering is a common symptom.

Zinc deficiency (Zn) is manifested by the lightening of the leaves (fading) between the veins on the blade of the young leaves, which remain small and twisted. It can result in infertility in trees.

Symptoms molybdenum deficiency (Mo) are similar to nitrogen. The older and middle leaves are initially blue-green, later light green to yellow. They die by browning. The plants do not bloom and stop growing. In the case of cauliflower, the so-called „Blindness“ – no flower rosette is formed.