Garden Center Blog

Treating Fungal Leaf Spot in Tampa Bay Ornamental Shrubs

April 10th, 2012

Customers often call with concerns about their formerly healthy ornamental hedges and shrubs. Once brilliantly green and thriving viburnum, Indian hawthorn or other evergreen bushes are now sporting yellowed foliage marred with brown mottling or spots like the ones on the right of the picture below.

Disease on Indian Hawthorn

Fungus on Indian Hawthorn - Click to Enlarge

Fungal leaf spot is a common problem in the Tampa area, as high humidity and the damp conditions following frequent rains contribute to the growth of fungal diseases. In hedges and ornamentals, fungus often first appears as a yellowing of the leaves. As the fungus grows, spots begin to be visible. The spots may be small and multiple or single and larger with uneven edges. Occasionally, the spots consume the entire leaf. Affected leaves may turn brown, tan or reddish in color. Left untreated, fungal diseases can cause leaf drop or even complete defoliation.

Leaf spot occurs when airborne spores are deposited on foliage, usually by the wind. In the presence of water, the spores are activated and begin to grow. Young plants, newly transplanted shrubs and recently pruned hedges are more susceptible to severe damage from fungal diseases.

Fortunately, eliminating fungal diseases in plants is simple. Dithane M-45 is a broad-spectrum fungicide that successfully treats and prevents leaf spot and other fungal diseases. For best results, you’ll need at least two and possibly three applications. To prevent leaf spot from forming, spray in the spring just as new leaves are beginning to appear and repeat a week or two later. A third application might be necessary after periods of heavy or frequent rainfall. To lessen the likelihood of leaf spot showing up in the first place, rake and remove all fallen leaves, as the spores often travel from leaf litter on the ground to the plants above.

Dithane M-45 is safe and effective for treating fungal diseases on hedges and ornamental shrubs of all kinds.

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