How to Cull Unity Shader Color Gradient Material in Scrollview?

I have a shader that makes a color gradient, I applied it to an image component of a child in my scrollview. This material isn't being culled when out of bounds of the scrollview. All other parts of the child are properly culled, just not the material gradient.

How can I edit this shader script I found online, to cull the material when out of bounds?

Shader "Custom/SpriteGradient" {
    Properties{
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Left Color", Color) = (1,1,1,1)
        _Color2("Right Color", Color) = (1,1,1,1)
        _Scale("Scale", Float) = 1

            // these six unused properties are required when a shader
            // is used in the UI system, or you get a warning.
            // look to UI-Default.shader to see these.
            _StencilComp("Stencil Comparison", Float) = 8
            _Stencil("Stencil ID", Float) = 0
            _StencilOp("Stencil Operation", Float) = 0
            _StencilWriteMask("Stencil Write Mask", Float) = 255
            _StencilReadMask("Stencil Read Mask", Float) = 255
            _ColorMask("Color Mask", Float) = 15
            // see for example
            // http://answers.unity3d.com/questions/980924/ui-mask-with-shader.html

    }

        SubShader{
            Tags {"Queue" = "Background"  "IgnoreProjector" = "True"}
            LOD 100

            ZWrite On

            Pass {
                CGPROGRAM
                #pragma vertex vert  
                #pragma fragment frag
                #include "UnityCG.cginc"

                fixed4 _Color;
                fixed4 _Color2;
                fixed  _Scale;

                struct v2f {
                    float4 pos : SV_POSITION;
                    fixed4 col : COLOR;
                };

                v2f vert(appdata_full v)
                {
                    v2f o;
                    o.pos = UnityObjectToClipPos(v.vertex);
                    o.col = lerp(_Color,_Color2, v.texcoord.x);
                    //            o.col = half4( v.vertex.y, 0, 0, 1);
                                return o;
                            }


                            float4 frag(v2f i) : COLOR {
                                float4 c = i.col;
                                c.a = 1;
                                return c;
                            }
                                ENDCG
                            }
        }
}

Shader "Custom/SpriteGradient" {
    Properties{
        [PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
        _Color("Left Color", Color) = (1,1,1,1)
        _Color2("Right Color", Color) = (1,1,1,1)
        _Scale("Scale", Float) = 1

            // these six unused properties are required when a shader
            // is used in the UI system, or you get a warning.
            // look to UI-Default.shader to see these.
            _StencilComp("Stencil Comparison", Float) = 8
            _Stencil("Stencil ID", Float) = 0
            _StencilOp("Stencil Operation", Float) = 0
            _StencilWriteMask("Stencil Write Mask", Float) = 255
            _StencilReadMask("Stencil Read Mask", Float) = 255
            _ColorMask("Color Mask", Float) = 15
            // see for example
            // http://answers.unity3d.com/questions/980924/ui-mask-with-shader.html

    }

        SubShader{
            Tags {"Queue" = "Background"  "IgnoreProjector" = "True"}
            LOD 100

            ZWrite On

         Stencil
         {
             Ref [_Stencil]
             Comp [_StencilComp]
             Pass [_StencilOp] 
             ReadMask [_StencilReadMask]
             WriteMask [_StencilWriteMask]
         }
         ColorMask [_ColorMask]

            Pass {
                CGPROGRAM
                #pragma vertex vert  
                #pragma fragment frag
                #include "UnityCG.cginc"

                fixed4 _Color;
                fixed4 _Color2;
                fixed  _Scale;

                struct v2f {
                    float4 pos : SV_POSITION;
                    fixed4 col : COLOR;
                };

                v2f vert(appdata_full v)
                {
                    v2f o;
                    o.pos = UnityObjectToClipPos(v.vertex);
                    o.col = lerp(_Color,_Color2, v.texcoord.x);
                    //            o.col = half4( v.vertex.y, 0, 0, 1);
                                return o;
                            }


                            float4 frag(v2f i) : COLOR {
                                float4 c = i.col;
                                c.a = 1;
                                return c;
                            }
                                ENDCG
                            }
        }
}