Dieback On Spruce Tree

Just from a photo alone it’s hard to diagnose a problem, but here are some of the things that could be happening here.
1. You say the spruce is 2 years old – by that we think you mean that you’ve had this plant in your garden for 2 years. If this tree was a balled-and-burlap plant when you bought it then this die back may be the typical response to having a large part of its root system cut off as part of the B&B process. Sometimes this adjustment is compounded by periods of drought and hard winters, such as we just had.
2. Physical damage. Bare areas such as this can be caused by the plant getting physically damaged by heavy snow or ice, falling branches from other plants, something heavy falling on the plant etc.
3. Shade. If this side or part of the plant is in shade it will drop needles since the plant won’t maintain foliage where no photosynthesis can happen. Spruce keep their needles in full sun, but if part of the plant is shaded it will shed needles and there is nothing that will prevent this.
4. Dry periods. If a plant doesn’t get a good DEEP soaking once a week (not just periodic sprinkling from an irrigation system or hand watering) it will shed older foliage in order to protect the new growth. Water your plants deeply with a soaker hose or sprinkler once every seven days. Use a rain gauge to measure rainfall or sprinkler delivery – you’re looking for about an inch a week in a gauge, not a carton or other container, once every 7 days.
5. Spruce spider mites. The least likely but worth considering. If you can honestly rule out the above, or a combination of the above, it might be mites. Call in an arborist or treat with a mitecide as insecticides won’t treat mites.