Roses: Gettig to the Root of the Problem

June is National Rose Month and with everyone’s roses in full bloom, it’s hard to imagine why they would not be enjoyed this month.  Roses are beautiful flowers and easy shrubs to have in your yard.

They are also fairly easy to diagnose when they have issues.  All the problems you encounter are generally a direct relation to its environment. Whether it’s bad drainage, too little water, poor soil, insects or diseases, these can generally be remedied or prevented.

Using the following information, you should be able to treat your roses and keep them healthy and happy. If you have a problem that doesn’t appear below, you can always ask Dan, our rose expert, and he will definitely be able to diagnose your problem.

*It’s important to note that when using insecticides, follow the product’s directions accordingly. In general, it is most effective to get the entire plant soaked with the product, including under the leaves.

Symptom: Bugs on the buds and leaves
Cause: Aphids which are green, red or black soft bugs about ¼” long, found on the new growth
Remedy: Insecticidal sprays or systemic granules can help treat and prevent future infection. You can spray the bugs off of them

Symptom: Blooms are shredded or discolored
Cause: Thrips which are light brown insects that are about 1/8” inch long. You will find them on the inside of the rose petals, moving quickly.
Remedy: Systemic granules with acephate are best for treatment because the thrips live in the soil.

Symptom: Leaves have holes in them, only leaving the skeletal structure of the leaf. 
Cause:  Japanese Beetle which are a metallic brown color with a green metallic head
Remedy: Unfortunately, there is not a lot you can do to prevent these guys. You will need to pick them off the plant and kill them or spray them when you see them. There are different traps available that you place away from your roses that work to attract the beetles and keep them off your plants, but it is hard to prevent them altogether.

Symptom: Fuzzy-looking leaves that are a yellow color. Webbing , red specks and spider-like insects moving about. 
Cause:  Spider-mites which are microscopic in size. They thrive in hot weather
Remedy: Insecticidal sprays, oils, miticides are the best treatment. You can also wash the plant off with a high pressure hose to thoroughly clean the plant.  Be sure that you get the underside of the leaves.

Symptom: Leaves and buds are discolored with a powdery, white or gray look to them. The leaves fold at mid-rib and are distorted.
Cause: Powdery Mildew which is a fungal disease that happens to a variety of plants. It is caused by cool nights and warm, humid days.
Remedy: Make sure plants have good air circulation and ample sunlight to prevent this from happening.  Once it has occurred, you can use a spray with a fungicide containing neem oil or sulfur.  There is also a home remedy of mixing 1 tablespoon of baking soda, ½ teaspoon of liquid soap and 1 gallon of water.  

Symptom: Brown spots on petals and brown dieback of canes. Lighter colored roses have red-pink spots
Cause:  Botrytis Blight is caused by high humidity and rainy cool periods. These weather conditions encourage fungus growth
Remedy:  Remove the damaged stems and clean up debris around the plant to prevent the mold from starting on those areas and spreading to other plants. Spray with a fungicide but this fungus can quickly become resistant to fungicides.  Keep good air circulation around the plant to help prevent the blight from coming back.

Symptom: Dark black spots appear on the leaves and they eventually start yellowing and dropping off the plant.
Cause: Black Spot is a fungus caused by rainy weather and improper watering
Remedy: Remove any debris from the plant. Spray with a Neem oil or fungicide that is sulphur-based. More than one application will most likely be needed.  Be sure to spray the underside of the leaves, which is where the fungus thrives.  To prevent this, try to avoid watering the foliage when you water the plant.

We carry some great 3-in-1 products for roses at the greenhouse that are miticides, insecticides and fungicides. These are great for general issues. If you have additional questions or are having trouble diagnosing your rose, feel free to bring a photo or a leaf in for Dan to take a look at.