Oso Happy Candy Oh! landscape rose by Proven Winners is an easy care, pest and disease free rose. Photo Amanda Jarrett
Disease & Pest free roses
Keeping roses happy and healthy is a sure-fire way to ward off any pests and diseases. Go figure!
So what do roses need to be healthy? These are the basics:
So what do roses need to be healthy? These are the basics:
- Start off right by purchasing a healthy rose plant.
- Do your research before buying. Local nurseries and rose societies know which roses are easy care in your area.
- Don’t place rose plants under trees or eaves where they will be dripped on from above.
- Roses require 8 hours of direct sun per day. Morning sun is ideal as it dries leaves quickly.
- Give them space. Space rose bushes away from other plants and each other as they need good air circulation.
- Water in the morning, not at night and keep water off the foliage.
- Provide adequate soil moisture. Dry soil promotes insects as well as diseases.
- Keep moisture in, weeds away and enrich soil with a 3 inch layer of mulch.
- Remove spent blossoms (deadheading).
- Water and fertilize after deadheading and pruning.
- Sterilize pruning tools after pruning infected or infested rose plants.
- Remove dead and broken branches immediately.
- Remove all suckers that emerge from the rootstock on grafted roses.
- Give them a nice long drink when they are flowering to help them out.
- Fertilize and water after each flush of bloom.
- Avoid full sun when applying insecticides and fungicides. Apply when it is cloudy but avoid rainy days as it will wash off.
- Apply dormant oil, lime sulfur combination in winter when the plant is dormant, usually January or February. This organic solution kills overwintering pests and diseases.
- Once a rose has been dug up, don’t replace with another as it will also become infected from the remaining spores and/or insects.
- Don’t be too much of a perfectionist as a few holes and blemished leaves here and there are no big deal. Just make sure that the plant is well watered and well fed and it should be able to fight back. It is the weak ones that succumb.
- Remember when you spray to kill the bad bugs, you are also killing the good good bugs that eat the bad ones.
rose diseases
When foliage and other plant parts are infected with a disease, the damage already done to the plant will not fix itself. Once the tissue is infected, any blemishes will remain on the plant. Look to the new growth, the new leaves and buds. If they are disease free and healthy, then the plant is on the mend.
Black spot
Black spot disease appears as black spots surrounded by a yellow halo. The leaves become yellow then fall off prematurely. The disease starts at the base of plant and works its way up. It is caused by rain, overhead watering, watering at night, not enough air circulation, overcrowding, too much shade, re-contamination from infested fallen and existing foliage.
Remove all infested leaves and plant parts from the plant and preferably, from the ground. Apply a fungicide as mentioned below, every 7 to 10 days. For black spot prone roses, it's best to discard them, especially if the infestations continually are severe every year. Don’t replace with another rose as it will also become infected. Plant resistant varieties! |
Powdery Mildew
Appears as a white powdery substance on leaves, buds, canes and especially new growth. Leaves curl then turn a grey-whitish color. It is caused by rain and cool nights followed by humid days, overhead watering, fog and dry soil: wet top and dry bottom! Remove all infected plant parts from the plant and the ground. Repeat spraying with a fungicide every 7 to 10 days is essential to ensure lingering spores are controlled.
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Controlling Diseases
When spraying plants pick a cloudy day without wind. Don't spray plants when they are sitting in sunshine as it will cause leaf damage. Spraying late in the day is a good idea as the product will sit on the foliage overnight. Thoroughly coat the plant, especially under the foliage and stems. Spray the soil as well, to kill any spores on the ground. Repeat spraying is necessary. The following are organic products, but they still should be used with care. Read product labels and follow their instructions.
Baking Soda
1 tablespoon baking soda
¼ teaspoon of liquid dishwashing soap
½ teaspoon of vegetable oil
1 gallon of water
Milk Spray: 1 part milk to 2 to 3 parts of water
Neem Oil: Derived from Neem tree seeds, this organic product also kills insects. Don't apply when plants are in full sun and within 2 weeks of applying sulfur products.
Copper Fungicides: This tried and true organic fungicide has been used for years to kill black spot, anthracnose, powdery mildew and many other diseases. Read the manufacturers instructions for rates of application and reapplication is necessary.
Sulfur: This organic product is a finely ground powder that, when mixed with water, is sprayed on plants to deter and control numerous diseases. It is has been used by gardeners for generations.
Baking Soda
1 tablespoon baking soda
¼ teaspoon of liquid dishwashing soap
½ teaspoon of vegetable oil
1 gallon of water
Milk Spray: 1 part milk to 2 to 3 parts of water
Neem Oil: Derived from Neem tree seeds, this organic product also kills insects. Don't apply when plants are in full sun and within 2 weeks of applying sulfur products.
Copper Fungicides: This tried and true organic fungicide has been used for years to kill black spot, anthracnose, powdery mildew and many other diseases. Read the manufacturers instructions for rates of application and reapplication is necessary.
Sulfur: This organic product is a finely ground powder that, when mixed with water, is sprayed on plants to deter and control numerous diseases. It is has been used by gardeners for generations.
Rose Canker

Dead, brown, discoloured areas appear on rose canes and small purple colored spots on the leaves. Caused by pruning wounds, insects and infected tools. A solution of Lysol and Pine Sol sprayed on the tools works well.
Avoid stimulating new growth with fertilizing or pruning. Remove infested plant parts well beyond the infection and sterilize the pruners after each cut. Remove plants for severe infestations as this disease is very difficult to control.
Avoid stimulating new growth with fertilizing or pruning. Remove infested plant parts well beyond the infection and sterilize the pruners after each cut. Remove plants for severe infestations as this disease is very difficult to control.
Botrytis Blight/Grey Mould
When rose blossoms and buds become a mess of dry brown petals that fail to open, the fungal disease botrytis is to blame. You might note a grey brownish fuzzy growth on flowers, buds and stems. Too much rain, fog and high humidity cause this disease. Good air circulation is an important prevention, so don’t overcrowd roses. Remove all infected plant parts from the plant and the ground and do not place in the compost. Water in the morning, not the evening. Keep moisture of the plant; water from below.
Too much nitrogen, deadheading and pruning, especially when the plant is wet, promotes this disease. Apply a 3 inch layer of organic mulch to prevent spores from splashing onto the plant. Apply a copper fungicide to help ward off the disease, every 7 to 10 days. |
Rose Insect Pests
Caterpillars

Many kinds of moth and butterfly larvae infest rose plants. They make homes in the leaves by rolling them inwards. They chew the tissue between the leaf veins skeletonizing them and they take holes out of them too.
Hand pick the caterpillars and any rolled and skeletonized leaves and any caterpillars. Spray with the organic biological control Bacillus thuringiensis (Bt, Thuricide) every 7 to 10 days. This pesticide only kills caterpillars.
Hand pick the caterpillars and any rolled and skeletonized leaves and any caterpillars. Spray with the organic biological control Bacillus thuringiensis (Bt, Thuricide) every 7 to 10 days. This pesticide only kills caterpillars.
aphids

Also known as black or green flies and there are many kinds that love roses. They collect in large colonies and feed on new growth. These sucking insect pests, suck the juice from the plant which distorts, stunts and curls leaves. Infested leaves seem pale and appear weakened. Aphids secrete a sticky substance called honeydew, which attracts ants. Don’t despair when you see ants as they are not pests, they are just there for the free meal. Honeydew breeds a fungus called black sooty mold, which looks like black soot. It doesn’t hurt the plant, except when it smothers the plant cutting off the light to the leaves. Use a hose and your fingers to squish and disperse the aphids. You can use soap and water, but really, the water works just as well. Go easy on the nitrogen, including organic plant food such as fish fertilizers. Nitrogen promotes lush new growth, which the aphids love.
spider mites

Spider mites are so small you need a magnifying glass to see them. Just like aphids, they are a sucking insect pest that produces honeydew. The visible signs are tiny spider webs, leaves become mottled, pale and dusty. Dry soil is the cause of most spider mites infestation so water well and apply a mulch. It is a common malady of roses grown in containers. To control, make sure plant is receiving adequate amounts of water.
Leaf cutter bees & Wasps
Perfect semi-circle holes cut into leaves are from leaf cutter bees and wasps. They cause no harm to the plant so no control is needed. Besides, these are beneficial insects because they are pollinators too.
Beetles: Japanese, Rose Chafer & Rose Curculio
Adults feed on foliage and flowers by chewing or boring holes into them. Severe infestations quickly defoliate plants. Japanese beetles feed on blossoms and skeletonize leaves so only their veins remain. Put out Japanese beetle traps to lure the adults, or spray with insecticidal soap, neem, pyrethrin according to the manufacturer's instructions. Or cut off infested plant parts and discard, don't compost.
Rose chafer devours flower buds making them difficult to control. Rose Curculio (Rose Weevil), burrows holes in buds. If you don't have too many, pick off them off and drop them into a container of water and dish soap. For more severe infestations, knock them off after you have placed a sheet under and around the plant, then discard them.
There are many types of beetle also have larva that feed on plant's roots. Plant wilt, lack vigor and die back. Sprinkle diatomaceous earth on top of the soil according to the instructions. The growing conditions and maintenance may not be correct or adequate so correct as needed so the plant can fight back.
Rose chafer devours flower buds making them difficult to control. Rose Curculio (Rose Weevil), burrows holes in buds. If you don't have too many, pick off them off and drop them into a container of water and dish soap. For more severe infestations, knock them off after you have placed a sheet under and around the plant, then discard them.
There are many types of beetle also have larva that feed on plant's roots. Plant wilt, lack vigor and die back. Sprinkle diatomaceous earth on top of the soil according to the instructions. The growing conditions and maintenance may not be correct or adequate so correct as needed so the plant can fight back.
thrips

Tiny, slender brownish insects feed inside flower blossoms and buds. They quickly hide deep inside the flowers when they are disturbed. Silver flecks appear on petals as they scraped then their juices removed. Flowers become brown, tattered and flecked. Cutting off and discarding infected flowers is an effective and quick solution. Thrips prefer it hot and dry so increase watering so they get a good soak. Repot potbound roses into larger containers and place a drainage tray underneath to act as a reservoir. When watering, thoroughly soak all the soil so it drains into the tray below.
Rose scale insects
They resemble miniature oyster shells and often reside along rose canes. Although they may look like part of the plant they are not and can be easily flicked off. Colours range from a dull white, grey or brown. They suck sap from plants causing them to wilt, leaves darken and soon fall off.
Prune out infected canes or wipe them down with rubbing alcohol, or flick them off with your thumbnail if there is not too many. |
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