Common Rose Problems and How to Fix Them

There are several very common rose problems which affect almost all rose varieties at some time or another. From fungal issues like blackspot and rust to pests like aphids, these diseases are all treatable if managed early (and often!)

If you start to see some issues with your roses, don’t panic. In this article I will walk you through identification, treatment, and prevention of the four most common rose problems

Blackspot

Blackspot Symptoms

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Rose blackspot is a fungus. It is often considered the most serious of the more common rose problems. The fungus spreads quickly from leaf to leaf and plant to plant and can significantly reduce the heath of your plant.

In its earliest stages, rose blackspot shows up on the leaves of your rose bush, as its name suggests, as small black spots. Often, these spots are on the leaves nearest the ground. The disease is often spread from the soil. For this reason, you could possibly miss noticing early stage blackspot.

The rose flowers look normal and the leaves are still glossy.

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The dark spots will start growing bigger and there will be more of them. The disease will be pretty obvious by now as the spots will be spreading to many or most of the plant’s leaves. If multiple roses are near each other, they will be sharing the disease.

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Left untreated, eventually the black spots get bigger, and you will start to see yellowing – this is the leaf dying from stress. Once you see the yellow, you are days away from the leaf turning brown and falling off. Younger canes could also become infected and will exhibit similar splotches as the leaves.

Blackspot usually doesn’t kill a rose plant, however the plant could be entirely defoliated. The plant will be very weak and susceptible to other problems including rust, aphids and stress. And when left untreated, after several seasons of blackspot, a rose might be so weak that it succumbs.

Blackspot Treatment

The first thing to do is remove all of the affected leaves. If the leaves remain on the plant, the fungus will continue to spread. Then, inspect, prune, and remove canes which are obviously affected. Clear away all of the dead leaves from underneath your plants, because the fungus is still alive even when the leaf is dead and could live in your soil, creating ongoing issues for both the remainder of the current year and also next year’s blooms. Do not compost or burn the leaves, rather discard them in your yard waste bin.

Next, treat the the entire plant with a fungicide. There are two types of fungicide; preventative and curative. Obviously, at this stage you need a curative fungicide, such as Copper, Mancozeb or Daconil. Also note that some fungicides are systemic and some not, so if you use a non-systemic fungicide, you need to treat every exposed area on your plant. If you use a harsh fungicide with metal like copper, you should lay down a cloth to prevent the heavy metal from leaching into your soil. This could affect your earthworm populations.

Preventative treatments will not be as effective at this stage, so make sure to read the label prior to purchasing or applying the fungicide. Most need to be applied on a schedule, such as weekly or every ten days throughout the growing season.

Even after applying the fungicide regularly, the black spots will not fade. If you have a successful application the fungus should be killed. However, the ugly spot, although dead, does not fade. However, any new growth should return clean.

Blackspot Prevention

Some roses are more susceptible to the blackspot fungus, and could lose all of its leaves. It helps to purchase roses which are resistant to blackspot. Floribundas roses such as “iceberg” are blackspot resistant. Although resistant, these varietiesare not foolproof. If nearby roses are diseased, icebergs could also get blackspot. When infected, these resistant varieties tend to rebound more quickly and respond to treatment well. There is evidence that the fungus mutates, so even some disease resistant roses can become defoliated when infected.

Planting roses with space in between is a great control, too, for two reasons. First, airflow reduces the ability of the wet spores to take hold. Second, space between plants reduces the risk of spreading the disease from plant to plant.

For your existing roses, once you have observed blackspot on a plant in a prior year, it is important to develop a preventative fungicide regime every year before the disease appears. Neem is a preventative fungicide, and one which does not create an unhealthy ’organic vacuum’ around your plant. This means that some fungicides kill ALL organisms, including the good ones like beneficial microbes, worms and ladybugs.

The methodology here is to treat rose plants early on in the season before they start exhibiting symptoms. Also promote a healthy plant which is able to resist disease by using appropriate organic fertilizer and drip watering (not overhead watering)

Rust

Rust Symptoms

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Another common rose problem is rose rust. This is also a fungal infestation, but this one actually grows on the underside of the leaf, so you may not spot it at first. When examining the health of your roses, be sure to check both sides of the leaf and look for orange spots or blotches.

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Rose rust starts out as small dots on the underside of the leaf, but as it grows the small orange or rust-colored dots combine to form larger splotches. Once the rust reaches a critical mass, the leaf will die and fall off. Unlike with blackspot, the leaf will not turn yellow prior to dying, unless combined with another issue. The fungus spreads much more rapidly than blackspot, so the leaf will just shrivel and fall off.

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In this third photo, the rust is rampant and the leaf has already lost all water. The leaf is starting to turn brown and with a slight breeze will fall off the bush.

Rust Treatment

Just like with blackspot, the first thing you need to do is to remove all of the affected leaves from the rose. If you do not, the leaves will eventually fall off and spread the fungus. Then, clear away all of the dead leaves from underneath your plants, because the fungus is still alive even when the leaf is dead and could transfer to your soil, creating ongoing issues for both the remainder of the current year and also next year’s blooms. Do not compost or burn the leaves, rather discard them in your yard waste bin.

Treat the entire rose with an organic fungicide. Repeat application. New growth will re-emerge where the infected leaves fell off. Reapply the fungicide so that the new growth is protected.

Rust Prevention

Water can spread rust. Rust has been shown to spread from overhead watering, or any water which splashes to the leaves. Switch to drip watering if you can. Try to plant rose bushes with plenty of space in between them. Otherwise diseases will spread from plant to plant. Prune the plants judiciously so that the center of the bush has plenty of airflow to dry out the leaves in between watering. And remember a healthy plant is often better able to resist disease, so fertilize judiciously in the spring.

Powdery Mildew

Powdery Mildew Symptoms

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This one is probably the most common of rose problems. However, not to worry, it is probably also the least damaging. It is rarely fatal.

Powdery mildew is the third of the triumvirate of common rose fungi. Although any plant can get this disease, roses are very susceptible to it, especially those in the shade or in high humidity. It is a white substance which looks more like a mold than a fungus. It can appear on any part of the rose, but often new growth.

Young buds affected with powdery mildew often fail to bloom, and instead turn brown and die off.

Powdery Mildew Treatment

Remove canes and buds which are affected by powdery mildew and treat with an organic fungicide. Again, dispose and do not compost. Water deeply and mulch to retain water at the roots. Try not to wet the leaves, rather water at the base of the plant.

Powdery Mildew Prevention

Some roses are more susceptible to the powdery mildew fungus, and could see flare-ups every year. It helps to purchase roses which are resistant to the fungus. Even then, a rose bush could become more or less resistant over time, depending upon the siting and environmental factors.

Plant roses in areas with full sun and good air circulation. Although they look beautiful, roses planted against a wall tend to be more susceptible due to lack of airflow. Mulch roses very well each spring and water deeply prior to budding. Dry roots are more susceptible.

Aphids

Aphid Symptoms

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Aphids are insects which are another of the common rose problems in the garden. Many gardeners will encounter these insects on several plants – tomatoes, broccoli, and kale are aphid favorites. However, any stressed plant will attract aphids, including hardy iris and succulent blooms.

Roses are aphid magnets. Even among healthy roses, aphids will park themselves on the buds that are just about to open, and along young canes.

They are tiny bugs – often white, or green, or even yellow – which reproduce extremely rapidly. Females give live birth to more baby aphids whom are often ALREADY PREGNANT at birth with the next generation. Aphids do not need males to reproduce.

Aphids harm and disfigure roses because they suck on sap and deposit a “honeydew”, or sugary substance all over the plant. This in turn can breed another type of mold on the plant leaves called “sooty mold”. Aphids also stress the plant and make it more susceptible to the other three common rose problems.

Aphid Treatment

Many aphids in the United States have shown resistance to insecticides. However, a strong jet stream of water usually knocks a majority of the insects right off of the rose. They have a hard time finding their way back to the plant. You may need to repeat the jet stream of water every day for several days, but this is generally the best way to treat for aphids.

Another extremely effective method is to introduce predator insects which eat the aphids. Ladybugs are my favorite little voracious aphid predator. I love seeing these little guys and girls in my garden, working as hard as I am to keep my roses healthy. If you are not in an area where ladybugs are abundant, you can purchase them, but please purchase sustainably harvested ladybugs. You can also purchase lacewings which are good aphid predators.

Aphid Prevention

Make your garden friendly for ladybugs. Install a ladybug house, and do not use insecticides that would harm them.

There are a number of companion plants which are effective at repelling aphids from roses, including catmint (nepeta), garlic and chives.