Which mineral deficiency causes the 'Exanthema' disease in citrus plants?

Deficiency of which mineral element causes the dormancy of lateral buds?

What type of disease is Rickets?

Name the deficiency symptoms shown by plants and their causative elements.

$A$: Manganese toxicity causes brown spots,chlorotic veins,and inhibition of calcium translocation to the shoot apex.
$R$: Toxic effects may be due to direct excess of micronutrients or their interference in the absorption and functioning of other nutrients.

If a plant shows a symptom which could develop due to deficiency of more than one nutrient,how would you find out experimentally,the real deficient mineral element?