Disorders producing symptoms mainly on the younger leaves

Deficiencies

The native reserves of molybdenum in many New Zealand soils are very low¹³. Although extensive planting’s of kiwifruit have been made on soils on which responses to molybdenum by pasture plants have been recorded¹³, deficiencies have not been observed in kiwifruit up to the present time. Solution culture studies suggest that the requirement for molybdenum by kiwifruit is extremely low.

Attempts to reduce dry matter yields or induce abnormal leaf symptoms by restricting molybdenum supply have so far been unsuccessful, despite molybdenum concentrations in the leaves being less than 0.01 µg/g dry matter.

Growth of many plants, including non-leguminous species, would be severely limited by similarly low concentrations of molybdenum²⁰.

Even in apparently healthy kiwifruit plants growing in the field, the concentration of molybdenum in the leaves is very low, usually ranging from 0.04 to 0.20 ug/g dry matter. It would seem from these results that molybdenum deficiency is unlikely to be a serious disorder of kiwifruit in New Zealand. However, a regular assessment of the molybdenum status of kiwifruit should be made as experience with other crops has shown that a lack of this element can cause an undesirable accumulation of nitrate in the plant tissue²³.