Symptoms

  • Deficiency symptoms first appear in the growing points of the palms.
  • The first symptom of B deficiency is the reduction in the elongation of young leaves.
  • The leaflets, when unfolding, are crinkled and shorter than normal, sometimes showing yellow or yellowish-orange discoloration.
  • In more advanced stages, terminal leaflets remain fused.
  • The tips of these leaflets may be 'knife-shaped', with or without a brown solution oozing out through the hook.This symptom is also called 'hook-leaf'
  • The basal part of the petiole may be without leaflets.
  • Gradually, the spear shortens and the leaves are reduced to an embryonic mid-rib without leaflets. This is the so-called 'little-leaf' stage.
  • Crown Rot disease or Crown Choke disease is due to Boron deficiency.
  • Inflorescence shows necrosis In the ultimate stage, the palm has only a central bulbous bud that does not develop any more, surrounded by some petioles without leaflets and finally, the palm dies.
  • The death of the affected palm is not sudden, but it slowly loses vitality and finally succumbs within 3-4 years. Roots of affected palms remain healthy and normal.
  • Drought may aggravate boron deficiency and in some cases one can observe seasonal boron deficiency i.e., the symptoms appearing in the dry season and disappearing in the wet season, giving the crown an appearance of tufts of leaves separated by parts of stem with very short or no leaves.
  • The critical stage at which the palms will not respond to treatment is when the leaves are withered and have a severely stunted apical leaf, crinkled leaves, and when some leaves lack leaflets .
  • Button shedding and production of barren nuts are the common symptoms associated with boron deficiency Other associated symptoms include 'Hen and Chicken' symptom (few under developed nuts / small sized nuts along with full developed nuts), partial filling of endosperm, nut cracking etc.