Borax is a sodium borate salt with 10 water molecules (referred to as decahydrate). It is a white powder that contains 36.5% B₂O₃ (boron trioxide), which means 11.5% B (Boron) as well as 16.5% Na₂O (sodium oxide).

Boron is an element required in small quantities for plant nutrition because:

• It is necessary for the synthesis of proteins.
• It aids in the absorption of calcium by plants and the normal development of the root system.
• It helps in the good flowering and fruit set of most trees.

In case of boron deficiency in the soil, calcium absorption is hindered even if calcium is abundant. Root rot may also occur, along with a reduction in both the quantity and quality of production, and in extreme cases, it may lead to the complete loss of production.

Boron deficiency often occurs in olives, beets, fruit trees, vegetables, cereals, etc. In Greece, we more frequently encounter boron deficiency in olives, almond trees, apple trees, and cherry trees.

Boron deficiency in olives exhibits the following symptoms:

• Chlorosis at the tips of the leaves.
• Drying out of the top of the tree and the appearance of dry branches throughout the tree.
• Appearance of the symptom known as "broom" on the tree.
• Reduced leaf size, and the leaves become club-shaped.
• Fruit drop before maturity and many fruits become shriveled.