We have a half acre of Vinca major around our home, we believed we got powdery mildew from wet steer manure, we treated with neems oil, and spots disappeared however now leaves are curling upwards and closing, eventually turning brown and dying. Any suggestions would be very much appreciated. Joe Borrie
If you spread fresh manure over your vinca, the concentrated nitrogen in it may have been too much for the root system. You may also have introduced any of several fungal disease that can attack vinca. Here’s a couple of links to more on that: https://www.gardenguides.com/100693-vinca-minor-diseases.html https://www.chron.com/life/gardening/article/Why-are-some-of-my-vincas-dying-but-not-others-1783083.php Vinca doesn’t like much food and likes to be dry so, if you have a sprinkler system that is watering it, adjust it so it doesn’t hit the vinca.