SENSITIVITY OF SUGARCANE (SACCHARUM SP) TO GLYPHOSATE

Field studies were conducted in Louisiana to determine growth and yield effects resulting from the accidental application of the isopropylamine formulation of glyphosate to sugarcane. Glyphosate at 0.1, 0.2, 0.4, and 0.8 kg ae ha-1 was applied in water at 90 L ha-1 in May, June, and August. Sugar yields (kg ha-1) were reduced 44% when glyphosate was applied over the top of sugarcane at 0.2 kg ha-1 in June; similar reductions for the May and August applications required 0.4 kg ha-1. Reductions in sugar yield were primarily attributed to reductions in both cane yield and recoverable sugar in the crushed juice because stalk populations and stalk weights were lowered and immature stalks that survived contained less sugar. The recoverability of the subsequent ratoon crop was also affected, particularly when glyphosate was applied in May and June to the previous crop at rates of 0.4 kg ha-1 and higher.