Question

Overall view  

Close up damage   I have five lugustrum plants that have been healthy since planting 5 years ago.  This year (since June) I have noticed spots on the leaves.  These spots are oblong in shape and appear to start on the underside of the leaves.  The leaves become very brittle and then turn yellow and fall off.  As new growth emerges some of the leave show a small brown discoloration which  turns into these larger oblong  scars.  The effected area of the plants is roughly 60-75%.  I am waiting for soil sample results but have treated with fungicides, systemic fungicides,  and insecticides with no noticeable results.

Answer
Sheila:

These spots are not a disease, but rather an insect that is causing the holes and the resulting damage.   These "punctures" can be a combination of feeding/egg laying sites.  I suspect that these spots will not have a significant impact on the overall health of your plants- mostly cosmetic.  Since diseases are my speciality, suggest that you collect a few of these affected leaves and watch the plant for suspicious insects on the leaves and collect them in a bottle and carry to your local county Agricultural Extension office.  This office is usually located in the courthouse building in the county seat.  They may suggest an appropriate insecticide such as Orthene or Malathion. Since many insects can overwinter on leaf debris, it is a good idea to rake up the leaves that fall to the ground and bag those up or burn them if allowed.  This can reduce activity for next season. If the damage is slight, you can consider pruning those heavily affected areas too.

Regards
Steve