Ivy is susceptible to a number of fungal leaf spots. The spots are caused by a variety of fungal species. They cause round to irregular spots in a variety of colors. Often small black specks, which are fruiting structures of the fungus, can be seen in these spots.
To control leaf spot diseases, remove diseased leaves or stems. It is also a good idea to remove old leaves and debris from the beds each spring before new growth begins.
Because these diseases require water on the foliage to infect, water the soil rather than the foliage if possible. Water early in the day so that wet foliage will dry quickly.
Fungicides may be used as protectants and need to be applied when new leaf growth begins in the spring. They must be repeated at 7-10 day intervals as long as wet weather persists in spring and early summer. Fungicides that are effective include fixed copper, mancozeb, thiophanate-methyl (Cleary's 3336-F), and iprodione (Chipco 26019).
This article originally appeared in the June 23, 1993 issue, p. 97.