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
Below is an example of Powdery Mildew
Below are examples of the early infection of Botrytis, also called gray mold
What is your tolerance for insect damage and fungal disease on roses?
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.
This is the first of four posts to supplement the information that will be presented on February 25th at 2:15- 3:45 in the Rainier Room.
Roses will uptake maximum nutrients when the soil pH is between 6.0 and 6.5. This reading changes in different locations of the garden. Other factors that change pH include use of chemical fertilizer and when the pH is tested, before, during or after the rainy season. West of the Cascades, the native soil tends to be acidic. (East of the Cascades the soil is alkaline) My Kitsap garden beds have had readings on October 2, 2016 between ph 4.5, pH 5.0 and pH 6.2. I applied granulated lime according to directions on the bag after these readings. You may have heard that lime is a slow acting soil amendment. I waited three months, until late December, to find pH in all rose beds to be pH 6.3 and pH 6.6.
I did not think this chart would project very well in the Rainier Room and even if it were projected, it seems to me to be something to study to fully understand.
The excitement is building now that the holidays are behind us. The 2017 Northwest Flower and Garden Show will be here before we realize it. This is the traditional kick off to spring in Seattle. Speakers and vendors crowd the convention center for a jam packed five days of garden glory. I love the display gardens to get inspired for the growing season. This year I will be speaking about roses on Saturday to kick off the the bare root rose growing season. I am so excited I can hardly wait. My program is finished and gets tweeked every week.
Competition roses in the Pacific Northwest are amazing! I recently returned from Vancouver, WA where I participated in the American Rose Society, Pacific Northwest District rose show. There were two main categories of competition: Horticulture and Arrangements. In horticulture, the hybrid tea rose is always the top winner and is awarded Queen, King, Princess. (I like that Queen is the best 😀) My favorite competition has always been making arrangements according to the guidelines of the American Rose Society. I still get a kick out of growing the roses and doing something pretty with them. Being recognized by my peers for good work is great too. It was a satisfying rose show for me.
I won the PNW trophy for my Oriental free style, naturalistic design using two containers. The roses are the David Austin variety ‘Graham Thomas’.
copyright Elena Williams
I was awarded a blue ribbon for a miniature mass design (10 inches). The roses are ‘Jeanne Lajoie’. I made several other designs winning blue and red ribbons.
Six years ago, Orion Roses in Minnesota had a going out business sale and I purchased several roses thinking this one was ‘Celestial’. It is not pink or ‘Celestial’ but since they business is gone, I have no idea what the identity of the rose is. It is quite large, drops it’s petals cleanly and forms oval hips and fills a space but I wanted a re-blooming rose in this location. Do you recognize this rose?
My first flush of roses is nearly over, but with the temps in the 50’s and 60′ for highs, the rebloom is moving slowly this year. Our Pacific Northwest District rose show will be Saturday June 4th down in Vancouver, WA and I need some sunny warm weather to compete!
Here are today’s blooms from the first flush of some of my Austin shrub roses.
I love the history of the Buck roses and I continue to increase my collection of his creations. Three are blooming today. ‘Spanish Rhapsody, ‘Aunt Honey’with a companion double clematis and ‘April Moon’.
Being outside in the fresh air and sunshine is my time to think. This year I have been thinking that my roses are blooming ahead of schedule but actually that is not the case it is just that last year my garden suffered through a nasty period of downy mildew and I had to do a second spring pruning to get rid of the diseased leaves and canes, so it felt that my roses bloomed late in 2015 and now early in 2016. They are looking fabulous now during my first flush. The roses below from top left are ‘Darcey Bussel’ ‘Boscobel’ bottom: ‘Prairie Sunrise’ ‘Show Stopper’ and ‘Mutabalis’.