Disorders producing symptoms mainly on the younger leaves

Deficiencies

The first sign of a deficiency is a uniform light-green chlorosis of the young, immature leaves (Photo 17a), later, the chlorosis becomes more intense in the interveinal area with the primary veins remaining dark green (Photos 17b and 17c); these affected areas may eventually become bleached (Photo 17d). Growth of kiwifruit is reduced by copper deficiency (Photo 17c), but results from the solution culture studies suggest that the effects are confined largely to the aerial tissues as there were no obvious effects on the roots. In the severe copper deficiency results in the death of the growing tip of the current seasons canes with the tips turning black. Premature defoliation of the affected canes is also common. Poor bud break is associated with low copper concentrations in these vines.

Copper concentrations in fully expanded leaves of healthy plants sampled in the field at mid season are usually about 10 µg/g dry matter. Results from solution culture experiments and from leaves collected in the field indicate that symptoms of copper deficiency do not usually appear until the concentration in the youngest fully expanded leaves falls below 3 µg/g dry matter.

Copper deficiency usually occurs on acid sandy soil of low total copper content, on organic soil, and on calcareous soils in which the availability of copper to the plant is low¹.

In New Zealand, soils low in copper on which kiwifruit are grown include the yellow-brown pumice soils in the eastern Bay of Plenty, and the yellow-brown earths derived from granite in the Nelson region of the South Island^52,53. While copper deficiency of kiwifruit in New Zealand is not common, deficiencies have been observed in orchards at Kennedy’s Bay near Coromandel, and on the Waimea Plains near Nelson. One factor which may contribute to the low incidence of this disorder is the widespread use of copper salts to preserve the timber used in the frames for supporting kiwifruit vines.

Soil applications of copper sulphate (25 % w/w Cu) at a rate of 25 kg/ha before bud break would seem to be the most effective treatment for correcting a deficiency as kiwifruit appear to be sensitive to foliar applications of copper salts, particularly if they are applied early in the season⁵⁵.

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17a	17b	17c
17d	17e