Boron Deficiency in Coconut
The leaf malformations caused by boron deficiency were first seen in the 1960s. They are shown by the youngest leaves and are more or less identical with the ones found in oil palms.
The symptoms, in increasing order of severity, are
- fusion of terminal pinnae on the frond
- “hook” or “bayonet leaf,” in which the pinnae are bent into a double or single hook near the tip
- development of the fronds with very short pinnae either on one or both sides of the rachis
- in the most severe cases, frond development without any pinnae
The first two symptoms are ones most commonly seen. Occasionally the apical growing point dies.
The first sign of boron deficiency on one-year-old coconuts is the development of small chlorotic spots on the young leaves; the spots are symmetrically orientated in relation to the main veins on the leaf. These boron-deficiency symptoms on very young palms bear a striking resemblance to those on young oil palms.