More Common Disease Problems in Roses

Photo Provided by FreeFoto

Photo Provided by FreeFoto

Yesterday we began discussing the many disease problems which can affect your roses. We covered how to diagnose and treat three different disease problems such gall, powdery mildew and downy mildew. Today we are going to talk about three more diseases which are common in roses and how to treat them.

Symptom: Yellow blotches on upper surfaces of leaves, small powdery orange or black postules on underside of mature leaves.

Cause: Rust—This is a fungal disease that may appear when days are warm and nights are cool and moist.

Treatment: Ensure that the rose plants have good air circulation and ample sunlight. If further treatment is necessary, you will need to treat with a fungicidal treatment that is listed for rust control.

Symptom: Brown dieback of cut canes; brown fuzzy mold on debris around the rose plant. In severe cases, the entire flower bud rots.

Cause: Botrytis blight (grey mold)—This fungal growth favors rainy cool periods or nights with high humidity.

Treatment: Remove all of the damaged areas of the rose plant and clean up leaves and debris from below the plant to prevent the fungus from spreading. Maintain good air circulation around your roses.

Symptoms: Dark black spots with irregular edges on the leaves. The spots tend to be round, varying in size from pinpoint to quarter-sized. Half of leaf yellows or leaf drops completely from the rose plant.

Cause: Black spot—This fungal disease favors rainy weather, poor air circulation or improper watering.

Treatment: Spray-Dust-Watering technique. After winter pruning, apply a dormant lime-sulphur spray. Remove dropped leaves and other debris. During the growing season, spray with fungicides listing rose black spot as a target on a rotational basis. Fungus spores are found on the undersides of leaves, so spray upward from underneath the rose plant. Spray in the early morning when the weather is calm and cool. Water your roses early to allow the foliage to dry thoroughly.

Now that you know some of the most common disease problems in roses, which ones have you had experience with? What have you done to control or eradicate the disease? Leave me a comment and share.

Identifying and Treating Diseases in Roses

Photo provided by FreeFoto

Photo provided by FreeFoto

This week we have been discussing the many different problems which are common in roses and are caused by insects. We discussed how to diagnose and treat insect problems such as beetles, rose midge, leaf cutter bees, rose cane borers, aphids, thrips, leaf rollers and spider mites. Now we are going to address several more common problems which may be affecting your roses, such as disease and how to treat those problems.

Symptom: Tumor-like growths on canes, roots, or at the bud union.

Cause: Gall (aerial, crown or root)—This is a bacterial pathogen that enters through a wound on your rose plant or by a pruning tool that is contaminated.

Treatment: Prune away any sections which are infected if possible. Sterilize your pruning shears and other hand tools with bleach or alcohol to prevent the bacteria from spreading. Any plants which are seriously weakened should be destroyed. You will need to treat the soil with a bactericide or leave it fallow for two seasons before you replant.

Symptom: White powdery material appears on young growth.

Cause: Powdery Mildew—This is a fungal disease that is fostered by warm days and cool nights.

Treatment: At first you should try spraying the affected areas with a solution of baking soda and dish soap. Make sure that the plants have good air circulation and an ample amount of sunlight. If you need to treat your roses further, then you will need to treat them with a fungicidal product for powdery mildew control.

Symptom: Dark, irregular splotches on foliage, dropping of apparently healthy leaves, sections of yellow leaves.

Cause: Downy Mildew—This is a fungal disease that may appear when nights are cool and humid. This mildew can develop very rapidly.

Treatment: Water your rose plants early in the day to allow the surface of them to dry thoroughly. Avoid overhead irrigation and prevent water from collecting around the plants. Cut the defoliated plant back. Clean up any debris and then dust with sulfur. Then spray the roses with a fungicide that lists downy mildew as a target.

Which of the above problems do you have or have had with your roses? Which methods have you used to eradicate the disease? Leave me a comment and share. Tomorrow I will discuss problems with rust, blight and black spot in your roses.