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May 27, 2020 5:39 PM CST
|My rose bush has black spots on the leaves. I've been removing the leaves that have the spots and spraying the bush down with Neem Oil everyday for about five days but everyday there are more leaves with black spots. What should I do?
Name: David Tillyer
New York City (Zone 7b)
May 27, 2020 8:35 PM CST
|You're up in Kingston and you've had nothing but rain. It's my understanding that that's perfect weather for black spot. I'm an hour south of you and I've got lots and lots of
black spot. I've been spraying with something that I think is awful for the pollinators. It's helping a little.
I've actually got something that's even worse for black spot. I have a rather small garden and a lot of rose bushes. The result is a lot of crowding. From what I read
crowding really is a breeding ground for fungus.
My plan is to remove about three or four bushes after the first flush and then prune the rest to a shadow of their former selves. Black spot is a curse.
Name: Dennis Brown
The Big Island, Hawaii
May 27, 2020 10:25 PM CST
|There are at least two recent posts, including mine, that address dealing with black spot. You can definitely get some suggestions concerning controlling black spot. FYI I used neem oil once with disastrous results. It didn't control black spot but left a slimy residue on the leaves.|
May 28, 2020 4:35 PM CST
|Stop spraying every day! That's too much. And you should never use any type of oil when it is warmer than 75 and when it is very sunny. You can burn your leaves.
The weather has been very good for black spot to grow. So it's been a problem in a lot of places. There are chemical sprays that can be used but they will not cure existing infected leaves. Those will continue to spot and die even after you spray. They will keep new leaves from getting it if you use them properly.
Take Dennis' advice and do a search on here for black spot threads. There is a lot of information available.
May 31, 2020 10:16 AM CST
|I am upstate New York also have have dealt with black spot every year for the past 5 years. Your post is an alarm for me that I need to consider taking preventative measure soon.
I have mixed experience:
Neem oil has never done much for me.
This year my approach will include spraying whole milk on the plants weekly. I read recently in my fruit tree bible "The Holistic Orchard," by Michael Phillips that milk is an incredible anti-fungal. The woman at my favorite nursery, Phantom Gardener, also told me milk is a nice solution.
I will alternate milk with a shot of liquid copper fungicide or sulfur every month or so. That is the plan this year, let's see what happens. Last year's black spot was so bad it wiped out a few of my favorite DA Charlotte's.
Name: Dr. Demento Jr.
Minnesota (Zone 3b)
Jun 7, 2020 3:15 PM CST
|I use Serenade, Sonata, Oxidate and Actinovate all work well but during periods of high humidity, frequent applications are a must.
Dousing the ground with the fungicides is just as important.
There are now more organic type fungicides out there; I hate to say it but a search on Googles shop will let you find out what is out there more quickly.
But you can find better prices, often, by not using Amazon which is now dominating online shopping.
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