Spray Now to Prevent Leaf Spot Diseases

Leaf spot diseases start developing in April on newly opening leaves of Rose, Photinia, Weeping Flowering Cherry, Dogwood, and Peaches. One way to reduce disease infestation is to clean up all dead leaves. Last year’s diseased leaves serve as a source for this year’s infection. Leaves of these trees and shrubs should be protected with a fungicide application as new leaves begin to grow in April. Leaves of Peaches and Nectarines must be sprayed as they begin to open to prevent peach leaf curl disease.

Organic gardeners can spray with lime-sulfur (calcium polysulfide), copper sulfate or Neem oil.

The most effective chemical fungicides are the systemic fungicides such as Propiconazole, Myclobutanil and Tebuconazole. Propiconazole is available in Fertilome Systemic Fungicide. Myclobutanil is in Spectracide Immunex Fungicide. Tebuconazole is in Bayer All-in-One Rose and Flower Care and Bayer Disease Control for Roses, Flowers and Shrubs. Propiconizole and Myclobutanil are applied as sprays to the leaves. The Bayer products are applied to the soil and taken up into the leaves from the roots. Systemic fungicides are translocated within the plant and stop disease development in already infected leaves as well as protecting new uninfected leaves.

Daconil and Chlorothalonil are also widely available and effective, but are not systemic and therefore protect only new uninfected leaves. In most cases you will have to look at the list of ingredients to find the technical, chemical names. Check labels to make sure the specific plant is listed. Read Labels completely and follow all instructions and restrictions. Peaches and nectarines have a more limited list of approved fungicides.