Maybe not. A rainy season in late Summer or early fall promotes development of the fungi. In those cases, you can expect to see more lesions on leaves. In dry seasons, I see fewer infected leaves. If you sell in a dry late Summer / early Fall, you may not have a big problem. And in a very wet late Summer / early Fall, I would consider applying a fungicide with one of these active ingredients: azoxystrobin, chlorothalonil, mancozeb or thiophanate-methyl. Some fungicide brand names associated with those ingredients are Heritage, Daconil, Dithane, Fore, Protect, Eagle, Immunox, Cleary's 3336 and Halt.
Good sanitation practices such as picking up plant debris, watering only the soil and replacing the mulch has kept my infected hydrangea shrub from passing this issue to other nearby hydrangeas for the last 16 years.
If you sell the house in Spring or early Summer, there may not be lesions visible yet. And none in the winter. But yes, you could also replace the shrub before putting the house for sale. Ironically, the fungi is "all over" the world and you may also find it in your 'new' home. I know, I know, sigh.... ;o)
Luis
