This looks like anthracnose fungus, infections are increased with humid environment. So you would need to move your plant away from receiving regular overhead water, most of all while in the shade. For treatment, there are many fungicides that are available at HD or on-line for this type of fungus. The best is to alternate treatments with different kinds. I have been using an organic one that works pretty well for me that can be used as a spray and root drench. It contains bacillus amylolyquefaciens and is available under various brands if you look it up on-line. I have not tried this on large plants in ground though. You definitely want to start quickly with a spray on and around the lesions to prevent further dissemination. The curling tips of the leaves may also be from too much water but in your case it looks more like fungus.

Agreed. I use Ortho MAX Garden Disease Control with good results. The stuff sold for rose bushes.