Instances are common in tomatoes apparently without detrimental effects. Older leaves develop interveinal yellow patches which eventually turn brown as the leaves desiccate. No other cases of deficiency disorders due to this element are known in NZ, though examples are common overseas. Copper deficiencies have occurred in lettuces and onions in peaty swamp reclaimed soils. Sound cultural practices based on observation, experience and planning will in most cases avoid the need for measures to correct a nutritional stress.
Prevention is better than cure.
Regular applications of commercial fertilisers prevent deficiencies of nitrogen, phosphorus and potassium from occurring, though supplementary dressings at the middle stages of growth beneficial for luxuriant or intensive plantings in the case of nitrogen or potassium. In addition where there is a history of phosphorus deficiency, care should be taken to raise the pH above 5.5 and summer crop plantings are best delayed until the soil has sufficiently warmed. Conversely where cases of boron, manganese or iron deficiency have occurred, past overliming with the development of alkalinity is indicated, and acidification would be advisable, using appropriate fertilisers eg ammonium sulphate. Calcium deficiencies rarely reflect inadequate soil calcium except in very acidic soils where the application of lime will be sufficient. More commonly these deficiencies reflect dry soil stress and an even watering regime should prove an adequate remedy.