Item 2. Reading Foliage

An examination of plant foliage often reveals whether the soil contains all food elements needed for good growth, and whether the plant is absorbing these elements properly. Plant scientists do this with leaf tests, actually checking concentration of various elements in the leaf itself.

Although not quite as accurate, leaf color tells a great deal about the way roots are taking up food elements from soil. This is usually a better check than a soil test which only reveals what is in the soil and not whether the food elements move out of the soil and into the plant.

Deficiencies Affecting Upper or Younger Leaves

Calcium: Terminal buds remain smaller than normal or are shriv­eled and dead; tips and edges of leaves brown and curled; balance of leaf not affected or only slightly yellowed.

Boron: Terminal buds similar to calcium deficiency. Leaf stems are brittle and base of leaf yellowed. Tips not affected until last.

Iron: Blade of leaf is pale or yellow while larger veins remain green. Smaller veins turn yellow with blade of leaf. Later, edges of leaves turn brown.

Sulfur: Entire leaf turns yellow, with veins brighter than blade. No further change throughout the season.

Manganese: All veins remain green while blade turns yellow. Later, blotches of brown appear over entire leaf (not only on edges as in the case of iron deficiency).

Nitrogen: Veins turn a reddish color while blade turns light green or yellow.

Deficiencies Affecting Lower or Older Leaves

Phosphorus: Veins and leaf stalks turn deep red or purplish. Leaf blade is mottled yellow, turning blotchy brown.

Potassium: Edges of leaves turn purplish, browning first at the tip but quickly extending along edges, which dry up and crumble away.

Magnesium: Leaf blade blotched yellow or tan while veins remain green. Leaves shrivel and fall in midsummer.

Zinc: Leaves do not grow in size but twist and grow crooked. Color is blotchy. Leaves fall early in summer.

General Foliage Effects

Overwatering: Effects are similar to iron deficiency.

Overfeeding: Plants may turn yellow all over, including stems. Remedy by flooding soil to wash out excess salts.

Mites, various insects and virus diseases: These may cause pecul­iar symptoms often confused with soil deficiency troubles.

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