Black Spot on Roses
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Black spot is one of the most common fungal diseases affecting rose bushes. The spots tend to be round, varying in size from pinpoint to quarter-sized. Yellowing of the leaf begins surrounding the spots and the entire leaf may yellow and eventually drop off. The fungus may also infect the canes where lesions appear purple at first and later black. Many frustrated gardeners wonder “what causes black spot on roses?”
It is believed rose black spot is caused by fungus. Spores are spread to the highly susceptible, young, unfolding leaves in spring by splashing water. Infection takes place only when water remains on the leaves for seven or more hours. Therefore, the disease is most serious in regions of high rainfall and high humidity. Because the fungus tolerates a wide range of temperatures, symptoms can continue to develop all season long if moisture is adequate.
Black spot can be distinguished from other leaf spot diseases by its fringed edges and dark black color. If black spot is left uncontrolled and early defoliation occurs, bushes are weakened and cane dieback the following spring may be severe. Weakened plants may continue to die even after the plants leaf out.
To get rid of Black Spot, remove any diseased leaves. Pick off and destroy any foliage that has evidence of black spot. Dispose of infected foliage in a sealed plastic bag. Rake up any fallen leaves from the soil surrounding the plant. Black spot as well as other fungus diseases are transmitted by water splashing back up onto the leaves and stems.
Control Products
Black spot is very difficult to eliminate once it appears. Prevention is the best form of defense. Spray fungicides early in the day for best results
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Controls Black Spot as well as other diseases and insects. Colored green to blend with foliage. Can be used as a dust or a spray. Controls other diseases such as, downy mildew, leaf spot, blossom blight and more. Controls insects such as, aphids, bagworms, tent caterpillars, Japanese beetle, gypsy moth, spittle bug & more. The most complete dust for ornamentals, roses, flowers and evergreens.
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his organic product has an OMRI listing. It controls bacterial spots, powdery mildew, rust, gray mold, leaf blight, scab, and more. Finally a fungicide that attacks harmful garden diseases, great for roses, vegetables, fruits, flowering plants, trees, and shrubs.
