What’s Wrong With My Roses?
Roses are prone to problems.
For example, if you grow an olderheirloom variety of roses, you may consistently deal with black spot.
The Spruce / Ulyana Verbytska
However, that’s changing as many modern roses are bred to be disease-resistant and low-maintenance.
These tiny, pear-shaped, sucking insects feed on succulent new growth, and their colonies grow quickly.
It’s a different fungus than black spot, but they share many characteristics.
The Spruce
It is due to the bacteriumAgrobacterium tumefaciensand interferes with a plant’s ability to take up water and nutrients.
This results in poor growth and weak plants that are easily stressed and injured.
The bacterium enters the plants through wounds, frompruning,transplanting, or breakage.
Mark Turner / Getty Images
Take these steps to avoid crown gall:
There is no cure for crown gall.
Crown gall bacterium overwinters in the plant and soil.
It spreads to other plants by splashing water.
Mark Turner / Getty Images
Do not replant roses in that spot for at least five years.
Japanese Beetles
Japanese beetlesare attracted to rose bushes.
They congregate in large numbers and quickly cause a great deal of damage.
Photo: Paul Bachi, University of Kentucky Research and Education Center, Bugwood.org
It’s hard to miss these bronze and green metallic beetles.
They feed on the leaves and skeletonize them, eventually defoliating the entire plant.
They can also devour and distort flowers and buds.
Photo: Cheryl Kaiser, University of Kentucky, Bugwood.org
The plant may not always exhibit symptoms and it might just decline.
Cutting out the cane with symptoms is only a cosmetic gesture but the virus remains active.
Avoid the problem by buying certified virus-free plants.
Box5 / Getty Images
Rose Curculios
Rose curculios are reddish-brown weevils with dark snouts.
They are only about 1/4-inch long, but cause a lot of damage.
Even their small, white larvae cause damage to roses.
Malcolm Manners / Flickr / CC By 2.0
Adult rose curculios feed on the flower buds by poking their long snouts inside.
They also deposit eggs inside the closed buds.
If the flowers open, they will be full of ragged holes.
Ingrid Taylar /Flickr / CC By 2.0
They are the larvae of sawflies, which are small flying insects.
They look like slugs because they secrete a slimy substance that covers their bodies.
A small infestation isn’t worrisome, as the damage is mainly cosmetic.
Allantus cinctusby MedioTuerto / Getty Images
However, a large population can severely weaken the plant.
This pest is also difficult to control with pesticides.
Here’s how to best manage thrips:
Powdery mildew and black spot are very common rose bush problems.
Jack Clark / Getty Images
Epsom salt can help roses growif your soil has a magnesium deficiency.
Have your soil tested for and amend it with Epsom salt if necessary.
A sickly rose bush will have rotted buds and withering or heavily spotted petals and leaves.
Bordeaux Mixture.University of California IPM Program.
Thrips.University of California Integrated Pest Management Program.
Chilli Thrips, a Growing Problem.Orange County Rose Society.
