B-carbohydrate complexes.
Boron toxicity is a rare condition that usually occurs during dry season when there is high B content in ground water.
How to identify ( symptoms)
- chlorosis of tips and margins of older leaves as initial symptoms.
- dark brown elliptical spots on dicolored areas , 2-3 weeks followed by browning and drying up.

How to manage
- Plant B toxicity tolerant varieties e.g ; IR42, IR 46, IR 48, IR 54, IR 9884-54). B toxicity tolerant varieties can yield up to 2 ton /ha more than susceptible varieties.
- Ground water must be monitored if used for irrigation. Use surface water with a low B content for irrigation.
- Plow when the soil is dry so that B accumulates in the topsoil and leach with water containing a small of B.