What is wrong with my roses.

[Lucecita]

Hi, I am a beginner and honestly, I have a hard time to keep my plants looking good. I live in south Florida. I have two roses in my front garden. They were just fine, but recently the leaves of one of them were turning yellow with a spot, but not exactly black.
I used Spectracide Immunox Multi-Purpose Fungicide Spray on both plants, and now the problem is happening on both. My husband says I have to plant cactus; they are easy. Any suggestion?



DORIS DAY FLORIBUNDA ROSE
EASY DOES IT FLORIBUNDA ROSE

 

[marlingardener]

You have black spot, which is common to some roses, especially Easy Does It. See the posts to Calicat https://www.gardening-forums.com/threads/help-with-shelias-perfume.15231/ for ways to prevent black spot. Being in south Florida, you probably have hot, humid weather which the fungus loves. We have the same here in Texas and I go through a fight with two of our roses every summer. So far the struggle is a draw .

 

[Lucecita]

@marlingardener thank you, I will try with another product.

 

[marlingardener]

Curing or preventing black spot isn't a one-time spray. You'll need to keep spraying after each rain, and at least once a week if there is no rain. The spores will persist for a while, but you can get a handle on black spot.

 

[Mike Allen]

Once a leaf has become infected. There is no miracle way of saving it. Pick it off and burn it. Some efforts to prevent can br tried but usually the plant is a victim by the time you notice it.

 

[Flatlander]

My roses had always been troubled by Black Spot. To prevent it, I've always done as suggested above. I picked off the leaves, bagged them, then took them to be burned. Due to local regulations, I'm not allowed to do this myself. As I know that the disease is fungal, and found in the ground, I've never thought this to be the ideal solution. Notice however, that I used the word "had" in my opening sentence.

In late 2017, I decided to lay the cuttings from my conifers in the rose beds to prevent weeds. Before anyone comments on this, yes, I know thats a risky thing to do. Despite hot days and cool damp nights during the summer of 2018 making for perfect conditions for Black Spot to thrive, the roses have never been healthier. My logic told me that the cuttings had something to do with this, and, initially, I thought that it was the toxins contained in them. Now though, my thoughts have changed. I discovered that conifers contain what is known as a predatory fungus called "trichoderma." This attacks the Black Spot fungus, and eradicates it.

As I understand things, Trichoderma is available at least to professional growers in powder or liquid form. Two teaspoons of it are mixed with 10 litres of water to treat the ground, and the actual rose bushes are treated twice a year with a mix of two teaspoons to 5 litres of water and a little soap. Worth trying, perhaps?

 

[Mike Allen]

Hello Flatlander. May I thank you for sharing your experience with us. I do my best to keep my replies simple, but as you may imagine, when a scientific link crops up I become re-charged. So reading your comment, recharged my batteries.

Usually many conifers are condemned by gardeners, especiall Leylandii. Some gardeners ask about disposing of the needles etc. These can be incorporated in compost. Now you have found a use for weed control. Although now being long retired from secular employment I am a plant pathologist and I have also studied and at times practice Homeopathy.

Here we have a real classic. Homeopathy treats like with like. Now in the plant world. We discover that crewation, the natural world we have basically the same. Trichloderma is a soil borne fungi and here, as in your experience basically we find one fungi fighting against another. Trichloderma is toxic, so please folks don't play around with it. There is much information on the internet including FAQ's and Wikipedia. Folks please read. Once again. Many thanks for posting.

 

[DirtMechanic]

@Chuck ? Thoughts? I ran into fungi that had no cure last year because I beat others back an had to deal with my success.

 

[Chuck]

@Chuck ? Thoughts? I ran into fungi that had no cure last year because I beat others back an had to deal with my success.

Without knowing what the fungi is it is hard to say. Over the years I have probably tried every chemical fungicide there is and used every homeopathy technique there is and sometimes no matter what you use or do you just can't win. @Mike Allen refers to trichoderma fungi and I have talked about it many times on this forum. Of all the chemical fungal treatments and homeopathic remedies, trichoderma has given me the best results over a wider range of plants and fungal diseases. Trichoderma is naturally in everyone's soil to a lessor or greater degree and the secret, IMO, is to produce or grow more trichoderma even though you may grow more harmful fungi at the same time. Whole ground cornmeal is the best growing medium for trichoderma and other harmful fungi but the added growth of the trichoderma negates the added harmful fungi or at least it seems to.
In my years of gardening I have come to realize that a healthy soil is the Number 1 reason some gardeners seldom get damaging fungi, diseases and insects while other gardeners seem to have multitudes of these problems and the only difference between the two is that some gardeners only use natural products in their garden while their counterparts use nothing but manmade chemical fertilizers and pesticides. Healthy soil has a healthy population of trichoderma fungi and to a lesser degree harmful fungi so it makes perfect sense that wholeground cornmeal will be of more benefit in a garden of healthy soil.

 

[DirtMechanic]

Thanks @Chuck . You have made me loosen a rusted mental gear thinking about it. Would it be like an apex predator pathogen that does not give you trouble, just your fungal enemies? The enemy of my enemy is my friend, in fungi speak.

 

[Chuck]

Thanks @Chuck . You have made me loosen a rusted mental gear thinking about it. Would it be like an apex predator pathogen that does not give you trouble, just your fungal enemies? The enemy of my enemy is my friend, in fungi speak.

Trichoderma is never harmful and I don't know if it is the top predator or not but it has to be one of the top predators. Like I said, it is in all soil but is reduced in unhealthy soil and by adding whole ground cornmeal you cannot but help increase it. Healthy plants or plants not under stress of some kind seldom are affected by harmful fungi and whether this is because of increased trichoderma or something else is the cause of many research projects. Now is seed planting time and before I started using cornmeal in my seed beds I lost a big percentage of seedlings to damping off disease. I can't remember the last time I had damping off and I use cornmeal religiously.