Aucuba Gold Dust is an evergreen shrub with spotted leaves. They prefer rich, moist well-drained soil in partial to full shade. They are a fairly problem free plant.

Your aucubas do not seem to be suffering from an insect or disease problem. The fact that your plants yellowing is uniformly over the older growth over both of the plants indicates that it is most likely caused by an environmental factor.

This year with the soil being colder longer and the weather being wetter than usual it has caused the roots of the plants to not be able to absorb sufficient nutrients. This has caused a nitrogen deficiency in your aucuba plants. Nitrogen helps the leaves of plants to maintain their green color and a deficiency shows up in the older leaves first. Once the soil warms up and the rains taper off the plants should rebound.

There is most likely enough nitrogen in the soil, so adding nitrogen to the soil will not remedy this problem any quicker. If you feel like you would like to do something to help your aucubas add an inch or two of organic material, such as compost, around the plants and work carefully into the soil around the plant without disturbing the roots. This is always a good idea to do each season to help maintain healthy, rich soil in your garden.

For more information: Landscape Plants - Aucuba japonica and Plant Nutrition Diagnosis.