Foliar marginal necrosis is the most common symptom of fluoride toxicity along with Chlorosis along and between the veins occurs in fluorine-sensitive plants. Symptoms appear on older leaves at base of plant. Plant dark green a. At first, all leaves are dark green and growth is stunted. Visual symptoms of phosphorus deficiency are not always definite, but many phosphorus deficient plants exhibit off-color green foliage with purple venation, especially on the underside of leaves, and plants are stunted and remain stunted even when fertilizers supplying potassium and nitrogen are applied.
Older leaves assume a purple-bronze color.
Phosphorus is phloem retranslocated from older leaves to new growth. Root tips blacken, no longer lengthen, but become thickened . Excess aluminum accumulation in roots reduces their capacity for translocating phosphorus. Amelioration involves suppression of aluminum activity, for example by liming to bring the medium's pH above 5.5, and not by addition of phosphorus. The toxic amount of aluminum in a soil will depend upon other soil properties such as pH and phosphorus content and upon the plant grown.