It seems that in most years any English ivy sample that makes its way to the Plant Clinic has either bacterial leaf spot or fungal leaf spot. This year, we already had two samples with no leaves at all. I am certain that means there is much more of this happening but not reported. The roots are not dead and not even rotted, so some of these plants may recover. The tops have cankers of several fungi, Botryosphaeria being the most common. The fungus is not the cause of the problem. These plants have been injured by winter—possibly the actual low temperatures of December and possibly the sudden drop in temperatures at that time. No one really knows for certain which is the case. The canker fungi that we find now have infected the dead or declining stems.
Fungicides are not warranted for the canker fungi. Remove as much of the dead plant material as possible. Water the bed when in drought stress but do so early enough that the foliage can dry before evening. We don’t want to encourage the two leaf spot diseases that are common in wet, humid conditions. If you would like to refer to a report discussing the leaf spots, consult Report on Plant Disease no. 652, “Leaf Spot Diseases of English Ivy.”