Nutrient Deficiency:Boron
Click on the image to enlarge
- 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.
