Molybdenum deficiency

General or mildly interveinal light green colour, and occasional clusters of pale necrotic spots on mature leaves (J. O'Sullivan).

- symptoms similar to nitrogen deficiency: general pale colour and stunted growth.

- mature leaves may develop pale interveinal patches, progressing to discrete necrotic spots in some areas.

- alternatively, discrete interveinal patches may appear silvery as the top layer of the leaf becomes separated from lower layers.

Molybdenum is needed for processing nitrogen, taken up from the soil as nitrate, into plant components. Therefore molybdenum-deficient plants become nitrogen-deficient, but at the same time accumulate nitrate in their tissues.