Problem with counting score in 3D game

Hello everyone! I'm using the 3D Game Kit from Unity to create a game concept. I'm trying to implement a scoring system, but when I start the level, the score appears with all the points of the collectable items in the level, rather than just appearing when I collect them.

I dont know where I'm going wrong.

Score Manager Script

using UnityEngine.UI;
using UnityEngine;
using System.Collections;

public class ScoreManager : MonoBehaviour
{
public static int score;

 Text text;


 void Awake ()
 {
     text = GetComponent <Text> ();
     score = 0;
 }


 void Update ()
 {
     text.text = "Score: " + score;
 }

}

Pick Up Script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class Valor : MonoBehaviour
{

 public int scoreValue = 10;

 // Use this for initialization
 void Start ()
 {

     ScoreManager.score += scoreValue;

 }


 // Update is called once per frame
 void Update () {
     
 }

}