First year Cascades. They've stopped growing vertically, but even when they were, I noticed the lower leaves slowly yellowing. Over the past 2 weeks, and really over the past few days, it has been very hot here and the leaves are drying to a crisp after yellowing from the outside in. They're watered, but not overly so. I fertilized once with some liquid Miracle Grow in a cut down proportion. No pests visible. Virus of some sort?