Zinc deficiency symptoms appear at early stage (usually 35 to 40 days after germination) of sugarcarJe growth. The initial symptoms start as loss of green colour (chlorosis) from the base of lower leaves which later spread upwards. The young leaves are completely chlorotic and soon develop brown patches (necrosis) from the tip downwards (Plate 1 & 2).

Soil or foliar application of zinc sulphate corrects zinc deficiency in sugarcane. The choice of method of application should be based on the extent and cause of zinc deficiency in the soil. In case of ratoon crop or main crop grown on soil with alkaline pH and high lime content, foliar application should be adopted to correct zinc deficiency. But soil application is cost effective and less cumbersome method.

Zinc sulphate at 25 kilogram per hectare is broadcast and incor¬ porated in top soil with the last ploughing.

Three to four foliar applications (at an interval of two weeks) of 0.5% zinc sulphate solution should be done as a prophylactic (preventive) measure or immediately on first sign of deficiency symptoms. For one hectare crop, dissolve 3 kg zinc sulphate and 12 kg urea (or 1.5 kg slaked lime) in 600 litre water. Spraying should be done in the late afternoon before sunset.

In zinc deficient experimental fields yield increase of 1.5 to 7.5 tonnes per hectare have been recorded. In ratoon crop, four foliar sprays increased the yield by 2 to 14 tonnes per hectare.