Crop Guide: Nutritional recommendations for Cucumber - Haifa-Group

solution. High soil pH reduces available copper, but this effect is much smaller than for manganese,
iron, and boron.
Copper deficiency symptoms
Restricted growth, short internodes and small leaves. Initially, interveinal chlorotic blotches appear
on mature leaves, but later symptoms spread upwards on the plant. The leaves eventually turn dull
green or bronze, their edges turn down, and the plant remains dwarfed.
Furthermore, bud and flower development at the top of the plant decreases.
Copper deficiency can dramatically reduce yield (by 20-90%). The few fruits that are produced
develop poorly with small, sunken brown areas scattered over their yellow-green skin.
Treatment
To prevent copper deficiency in peat media, where it is most common, add copper sulfate at 10
g/m³, as a precaution. Generally, nutrient solutions should contain 0.03 ppm Cu. For quick results,
spray plants with a solution of copper sulfate using up to 1 g/L, plus calcium hydroxide (approx.
0.5%) for pH adjustment.
Table 3.15: Leaf analysis copper standards for field-grown cucumbers (in dry matter of youngest
fully mature leaf with petiole taken at early flowering stage).
Nutrient Unit Deficient Low Normal High Excessive
Copper mg/kg 30
Values for copper in leaves sprayed with fungicides or nutrient sprays containing trace elements cannot give
a reliable guide to nutritional status.
Toxicity
Copper toxicity, although rare, can appear as an induced iron chlorosis, where the soil is
contaminated with copper either from industrial sources or after repeated spays of coppercontaining
fungicides. Toxic effects persist, and the only partial solution is heavy liming. In
hydroponic systems, extensive use of copper plumbing can produce copper contamination.
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