#NWFGS Third supplement

Identify the problem with your roses

Before taking any action, be certain that you identify the insect or fungal disease and use the Integrated Pest Management (IPM) approach to a pest free garden. If your roses do not have to be perfect, then you can tolerate a certain amount of insects. If you want exhibition quality roses, then you may have to rely on more chemical control.

Fungal diseases do not go away when no action is taken. Once a leaflet shows disease, it will not go back to the way it was before infection. You can begin by cutting off (not tearing) the infected parts of the bush. If you wait too long, the plant will naturally shed the leaves (defoliate) but in the interim, the fungi spores continue to multiply and blow around your yard.

Below is an example of blackspot

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Below is an example of Powdery Mildew

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Below are examples of the early infection of Botrytis, also called gray mold

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#NWFGS second supplement

What is your tolerance for insect damage and fungal disease on roses?

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It is a personal question and the answer can change depending on the uncontrollable factor of weather or the amount of time you have to devote to roses or your personal philosophy of what is the right way for you to garden.

I prefer to not use insecticides in my garden because I have fruit trees and mason bees that I nurture for pollination of my fruit. When aphids come to visit my roses, I often see ladybugs working on them, but I often get my hose with a medium spray nozzle and blast aphids with water for a few days in a row. The aphids fall to the ground and since they cannot fly, most do not return. If they are not removed, aphids continue to reproduce and damage roses.

If we have a hot dry June and July and I suspect spider mites will be active. Again, get the hose out with a spray nozzle. Spraying water and a slight rubbing of the leaves, especially on the undersides will deter the spider mites. So the word “spray” is not a bad word in my garden. I spray water, I spray liquid seaweed, I have been known to spray chelated iron and products approved for organic gardening.

Fungal diseases can do a lot of damage is a relatively short period of time. Once you see the damage, you cannot return the foliage to perfect again. As soon as a fungal disease shows, it is best to trim off (not tear off) the disease and do what you can to stop it from spreading. Some roses are resistant to fungal disease by hybridization. That is why you may see one or two roses badly defoliated (in a public garden for example) while others in the area stay clean.

The photos are examples of the continuum of possibilities for your rose garden. The amount of time you have to spend in the garden may change from year to year. Do not get discouraged if pests and disease appear. Contact a local Consulting Rosarian for help.

Local help for roses

A few roses begin to bloom

What a difference a few warm days can make in the garden.

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This is the first bloom of ‘La France’ in my 2014 garden.

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‘Prairie Lass’ is a Griffith Buck rose I enjoy because of the stippling of the color on the petal.

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Yellow roses are my favorite and this three year old ‘Cl. Golden Showers’ is spectacular, but the foliage is showing blackspot by mid May, so I plan to remove this plant and look for a cleaner rose. Too bad because I like the flower.

Blackspot or Downy Mildew?

Are you seeing spots? Rosemania will help you identify the fungi.

Rose Growing Tips

I get emails from many rose growers in spring and fall who think they have blackspot.   Many of them have been treating for this disease and don’t understand why the fungicides they are using are not working.    In most cases I find they have misdiagnosed their problem and what they actually have is downy mildew.

I will talk about how to control both diseases in future blogs, but for today let’s focus on what they look like.

Blackspot (Diplocarpon rosae) starts as a small black spot/spots on otherwise green healthy leaves.   As the disease progresses, the leaves get more spots and the green tissue begins to be replaced with yellow.  Usually within two weeks of infection the leaves will begin to fall and the entire plant may be defoliated.  Left untreated the plant will try to put forth new growth, only to also become…

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