Rose Disease Black Spot on Roses

Rose Bush Care

This extremely common fungal disease, infects rose foliage, causing circular black spots with fringed margarins. This fungus ( Diplocarpon rosae) is a severe problem where there is high humidity or lots of rain.

The fungus lives through the winter on infected leaves and canes. The spores are spread from plant to plant from splashing water and rain. The fungus enters the tissues of the plant, and forms tiny pinhead size spots. The black spots on roses enlarge as the fungus spreads, to the point that, spots may join to form blotches.

Black spot spreads quickly when the weather is wet or humid and warm.

When this rose disease severly infects the plant, foliage turns yellow and drops off prematurely. If left unattended, plants may lose all of their leaves by midsummer.

Plants infected with this lose vigor, and flowering is greatly reduced. For this disease to take hold, the fungal spores must stay wet for around seven hours. Wet foliage overnight, or a rainy day, readily allows the infection to start.

Black spot on roses is most severe in regions with higher rainfall, including the Southeast, Northwest, and the East, but it can occur anywhere, in any area.

Rose Bush Care Tips

The first and easiest way to avoid this rose disease, is to purchase roses that are immune to it. Many varietys have very good resistance to it. (Check the label when you buy)

If you already have plants in the garden:

Avoid watering from above. Spraying the leaves with water from above, only encourages the spores to take hold.

Rake and destroy fallen leaves in the fall (Do Compost them)

Space plants to ensure good airflow and drying after the rain.

Prune the plants to "open them up" and allow good air circulation.

Water in the morning to minimize the time that the plants stay wet.

At the first sign remove infected leaves (do not compost) and begin spraying a sulfur-based fungicide or a soil inoculant every 5-7 days for control.

Use this Liquid Organic Fungicide to prevent and control black spot.

This Organic Rose and Ornamental Plant Spray Controls a wide range of fungal diseases and pests!

Controls fungal diseases such as black spot, scab, powdery mildew, rust, blight, brown rot and leaf spot.

Controls insect pests such as aphids, leafhoppers, caterpillars, whiteflies, spittlebugs, mealybugs, scale, thrips, psyllids, fruit flies, earwigs, chiggers, roseslugs and mites.

For the Complete Spray guide for roses take the guess work out of your rose bush care!

Go from Black Spot rose disease back to rose diseases and pests

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Disease Resistant Roses