You are using an old format. It should be
uniforms[ "tDiffuse" ].value = THREE.ImageUtils.loadTexture( "color.png" );
See the Migration post at the three.js Wiki: https://github.com/mrdoob/three.js/wiki/Migration
texture uniform changes: texture units are now assigned automatically, texture object goes to value property instead of texture one { type: "t", value: 0, texture: map } => { type: "t", value: map }