Treating Photinia for Entomosporium m.

Asked January 22, 2020, 1:52 PM EST

Hi, Do you have any information on using a diluted cow's milk spray to manage entomosporium on Photinia hedges? We have been successfully using it as a foliage fertilizer and to treat roses for black spot, powdery mildew and for some sucking insects on commercial properties for the past year and are hoping to do the same for some very sadly afflicted photinias. I believe the fungi are different...? Thanks! Sue Thompson

Lane County Oregon

1 Response

The short answer is no. I have tested Whey on grape and rose powdery mildew before and have see activity with it. The nature of powdery mildews is such that their hyphal threads are mostly on the outside of the plant. They also do not do well under wet conditions. These factors make them susceptible to management with alternative products such as milk. Similar aspect for insects like aphids. I am not so sure that the black spot control is all that great with milk.
As for Photinia leaf spot, I am also not sure it would do much good. These fungi are favored by wet conditions unlike the powdery mildews. If the leaf spot is caused by a physiologic problem then it would not work at all. So be sure to get a good diagnosis.
Removing the infected leaf litter below the hedges for several years would help reduce disease pressure and make alternative applications such as this a bit more effective.
In the end it is not you or I who determines its effectiveness but your customer. If they like the results then who am I to say otherwise. Let me know how to works out for you if you go ahead and try it this spring. Bud break would be the time to start.