Rhododendron Plants
Q.

Downey mildew

Zone Portlsnd, Oregon 97230 | Hheisey1000 added on April 8, 2017 | Answered

How to kill Downey mildew? Last spring I found leaves becoming brown and dropping off on. 3 Rhododendrons planted close together. It was finally diagnosed as Downey mildew and I sprayed off and on all summer. We had a very cold, wet winter and the spring is not much better. The mildew is still present on the plants and I am wondering what is the remedy to kill it? They are very mature plants and I would hate to lose them but fear that is going to happen. I live in Portland, Oregon and communicated with master Gardners last year but their suggestions have not worked. Any suggestions? Harriett Heisey [email protected]

A.
A.Answers to this queston: Add Answer
roseman
Answered on April 9, 2017

I suggest spraying the plants with a product called Green Cure at 4 to 5 day intervals for at least 5 sprayings. Be sure to mix the product with water at the Cure Rate listed on the product label. Downy Mildew is a tough customer to get rid of, so you must keep after it. If things do not appear to be improving after the 5 spraying regimen. Then do yet another regimen of spraying. Another option would be spraying with a fungicide known as Mancozeb. It does leave a yellowish powdery residue on the plants leaves but that is part of how it works. Use the Mancozeb at 7 day intervals.

00
Was this answer useful?

Log in or sign up to help answer this question.
Did you find this helpful? Share it with your friends!

You must be logged into your account to answer a question.

If you don't have an account sign up for an account now.

Looking for more?
here are more questions about...
Rhododendron Plants
Join Us - Sign up to get all the latest gardening tips!

Do you know a lot about gardening?
Become a GKH Gardening Expert

Learn More