Phosphorus deficiencyPhosphorus (P) deficiency is a plant disorder that is most common in areas of high rainfall, especially on acid, clay or poor chalk soils. Cold weather can cause a temporary deficiency.
All plants may be affected, although this is an uncommon disorder. Particularly susceptible are carrots, lettuce, spinach, appless, currants and gooseberries. Symptoms include poor growth, and leaves that turn blue/green but not yellow—oldest leaves are affected first. Fruits are small and acid tasting. Phosphorus deficiency may be confused with nitrogen deficiency.
It can be controlled by applying organic sources of phosphorus such as rock phosphate.
Plants that are naturally adapted to low levels of available soil phosphorus, however, are more likely to suffer from phosphate poisoning: the key is to provide the right level for any particular plant type, neither too high nor too low.
Other physiological plant disorders include;