Temperatures are falling, finally. The heat toll was too high for my zonal hybrids. Few zonals and many of my Regals have fared well. My species, however, were completely intact. I will keep those which fared well for a new generation from seed. Wake me up when September ends...

The peak of the heat was between June and July, and this is when the problems have started. The growth tips of the zonals were very pale, and fertilizers did not seem to help. They were yellow, almost white, and growth was stunted. Even green shoots were often stunted. Looking closely, it seemed like they had a terminal leaf instead of a growing tip. The tips were brittle and often turned brown. The disease does not seem to spread very quickly, but plants affected will suffer throughout the summer.

The first picture shows a brown ring of vascular bundles, where one of the side-shoots or maybe a leaf broke-off.