Viburnum , also cognize as nannyberry or American cranberry bush , grows as a bush or small tree . Native to the easterly United States and hardy through U.S. Department of Agriculture Zone 2 , viburnum ’s magnet let in lustrous , dark-skinned - greenish leaves and bunch of white flowers . In the autumn , the flowers give way to shining berries that deepen chromaticity , go from green to yellow to blood-red and then black . Viburnum is resistive to many serious disease , although some kingdom Fungi and bacteria can attack the species .

Leaf Spot

Various fungus , including the anthracnose fungus , can cause viburnum leaves to develop black , sunken lesion . The wound can spread across the folio surface and finally dry up and turn red or grayish - brown . Joey Williamson , Clemson University Horticulture Extension agent , says fungal leaf spot are a common , but usually not serious , issue for genus Viburnum , especially during periods of high humidness or rain . Williamson apprise planting viburnum far enough apart to provide good air circulation around the leaves .

In improver , to ward against folio blot , debar water the flora from above to keep leaves as juiceless as potential . Pluck off pathological leaves still on the works and dispose of fall leaves to keep the disease from spread out . antimycotic spray that contain chlorothalonil , thiophanate - methyl , myclobutanil or mancozeb also can help control leaf daub .

Powdery Mildew

Downy Mildew

pubescent mildew come out both as light green lesions or blotches on the upper leaf surfaces and a white powder on the lower leaf surfaces , according to the Ohio State Extension service . The lesion turn cerise and then chocolate-brown , then dry out . The disease can cause leaves to drop off the viburnum . The powdery mildew fungus prefers wet conditions and cool or warm weather . Since the mildew spores can survive through the wintertime , gardeners should strip up any come leaves or plant debris regularly . A fungicide containing mancozeb or chlorothalonil is effective against fluffy mould .

Bacterial Blight

Various strains of Pseudomonas syringae induce this disease . The symptoms include diminished black spots or large brown spots on leaves , blackened leaf veins and dead blossoms and stem crest . Some works may develop stem lesion or pestilence that seep liquid . Blight bacteria prefer wet weather , including rainy springtime weather . Proper spatial arrangement and steady pruning can help prevent bacterial blight .

To keep the disease from spreading , comprehend humble industrial plant with plastic , the University of California ’s Integrated Pest Management Program ( IPM ) advises . Sprays are not good against the disease , according to IPM .

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