Dorothy is a Master Gardener, former newspaper reporter, and the author of several books. Michael is a landscape/nature photographer in NM.
Roses Aren't Problem-Free
I love the roses here in New Mexico. Some of our neighbors have some stunning ones growing out in their front yards and I have admired them with envy since we moved into our current neighborhood. Our roses, however, were another story altogether.
We have a nice brick-enclosed, 6 x 12-foot oval area in our backyard and the first photo with this article should give you a pretty good idea of what the entire area looked like. It was a mess that I couldn't leave alone - I had to cure whatever was ailing it. Neglect was the biggest problem.
The area had become so weedy that the roses hadn't seen sunshine in years. So, I simply started cutting . . . and cutting . . . and cutting. We moved into this house in June and by late July the roses were as beautiful as I assumed they had been before the neglect. I fertilized, watered, and deadheaded and the plants sprang back to life.
I learned a lot about roses during that summer and hopefully, this article will help you with some of the problems you might be facing with your own roses.
Before and After Practicing What I Preach
Rain, blown about by the wind, can cause you to have some small deposits of an orange powdery substance called rust on the undersides of your plant's leaves. Rust is a fungal disease that will cause the leaves to become mottled with yellow. New stems can become twisted as a result.
There are three things you can do to keep rust under control - keep the foliage dry, spray with the botanical pesticide neem, and practice good garden sanitation.
- If you do have an outbreak, spray the plant with neem or a synthetic fungicide for roses that contains either ferbam, mancozeb, or maneb as its active ingredient.
- When you water your roses, water them in the morning so they have time to dry before dark.
- Remove the fallen leaves and stems, even if they show no signs of the disease.
- In late winter, when your plants are dormant, spray them with organic lime-sulfur fungicide (again, follow the directions).
What Rust Looks Like
Botrytis blight is also called gray mold and it is caused by a fungus that actually thrives in cool, damp conditions, much as in early spring. A black mold can develop on rose buds and it is usually accompanied by fuzzy, gray mold on leaves and stems nearby.
If you do have blossoms that are affected, they will have brown specks and spots of the mold and completely fall apart when you touch them.
The Solution to the Problem of Botrytis Blight
- First, clip off all affected stems, buds, and blossoms; and prune the plant which will improve air circulation and allow it to dry quickly when it rains.
- If damp weather continues, spray the affected plant (and neighboring plants) with organic copper-sulfate fungicide, or neem. You could also spray them with a synthetic fungicide for roses that contains captan as the active ingredient.
The Effect of Botrytis Blight on Roses
The Darn-Near-Invisible Thrips
Thrips are minute, slender, fringed insects that are often translucent white, and they can ruin some otherwise-beautiful roses by causing the buds to droop or only open partially. The petals on blossoms that have opened will have brown scratches and bumps, and brown edges that are curled.
These nasty little insects feed inside the roses by puncturing and sucking, and the only way you can see them is by placing a blossom over a sheet of colored paper and tapping it. Insects inside the blossom should fall out and you can examine the paper for these squirmy little buggers.
The Solution to Thrips
- If you are plagued often by thrips, consider growing dark-colored roses, which are apparently less attractive to these insects than the lighter ones.
- Handpick any blossoms that have been affected and remove them completely from the garden area.
- Spray your plant with insecticidal soap, neem, rotenone, or pyrethrum. You could also use a synthetic insecticide for roses that contains one of the following active ingredients: malathion, carbaryl or diazinon.
- To prevent any future infestations, spray your plants with garlic oil, which will repel the thrips.
- Always deadhead your roses as soon as the blossoms fade (healthy flowers that have faded can also become a great host for thrips).
Tiny, Translucent Thrips
Aphids, like thrips, will damage your rose plants by sucking out the juices, although aphids feed on buds, leaves and tender, young stems. From spring to early summer, hundreds of them will cling to your plant, causing new leaves to possibly by yellow and curled.
Aphids excrete a sticky substance called honeydew that can sometimes cause sooty black mold to develop on a plant.
Solutions for Aphid Infestations
- Dislodge them from the plant by hosing them off. You might want to do so on a dry day when there's a slight breeze so that the leaves will dry quickly.
- Spray your infested plants with insecticidal soap, neem, pyrethrum, or rotenone.
- You could also spray them with a synthetic insecticide for roses that contains any of the following ingredients: malathion, diazinon, or dimethoate.
- If your problem with aphids is a chronic one, spray a light horticultural oil in the early spring to smother their eggs. To repel them from future infestations, spray your plants with capsaicin or garlic oil, both of which work great, as the aphids seem to hate them.
Aphids on Rose Stem Tips
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2019 Mike and Dorothy McKenney
Pamela Oglesby from Sunny Florida on January 07, 2019:
I love roses and have grown them often over the years, and I agree that you have to watch them carefully. Your article is great for all of us to know how to treat the problems that arise when growing roses.
Chitrangada Sharan from New Delhi, India on January 06, 2019:
A very useful article about rose gardening.
I love growing this beautiful flower and sometimes, such problems do occur. Saving your valuable article for future reference.
Thank You for sharing.