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iTen Essential Steps to Prevent/Control Dogwood Anthracnose
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Dogwood Anthracnose and its Spread in the South
United States Department of Agriculture Forest Service Southern Region
Knighten, USDA Forest Service, Region 8, Forest Health Protection, Asheville, NC; Mark Windham, University of Tennessee, Knoxville, TN; Keith Langdon, Great Smoky Mountain National Park, Gatlinburg, TN; Floyd Hedrix and Ron Roncadori, University of Georgia, Athens, GA.
http://fhpr8.srs.fs.fed.us/pubs/dogwood/r8-pr26/dwr8pr26.htm
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ABSTACT
In the 15 years since it was first reported in the United States, dogwood anthracnose (caused by Discula destructive sp. nov.) has spread rapidly and caused serious losses among flowering dogwoods (Cornus florida L.), particularly in the South. Infection begins in leaves and spreads to twigs and branches, which dieback. Main-stem infections cause cankers, which kill the trees. In the South, infection is most likely at higher elevations and on moist to wet sites. Shade increases risk of infection and mortality. High-value trees can be protected by mulching, pruning, and watering during droughts, and applying a fungicide.
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Figure 1 -- Small leaf spots caused by Discula destructiva. |
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Leaves clinging to stem in winter. |
Ten Essential Steps to Prevent/Control Dogwood Anthracnose
- Know the symptoms of dogwood anthracnose and other problems that commonly affect dogwoods. Inspect trees frequently to detect the presence of the disease in its early stages.
- Select healthy planting stock. Never plant diseased stock. Purchase trees from a reputable nursery. If symptoms are seen on the planting stock, dispose of the infected trees. Avoid transplanting trees from the forest, especially from mountainous areas.
- Select reasonably well-drained planting sites with fertile soils. Avoid sites along streams, lakes, or ponds where moisture will remain on the foliage for many hours after sunrise. In high-hazard areas, plant flowering dogwoods only in full sun.
- Planting holes should extend well beyond the root system of your planting stock, and should be filled with a rich mixture of soil and humus. Be sure the root collar is placed at ground level.
- Mulch around newly planted and existing trees to a depth of 2-4 inches. Be sure the mulch does not touch the stem, and avoid using dogwood leaves or chips.
- Prune and completely remove or destroy dead wood in the tree and leaves on the ground yearly. Avoid flush cuts, being sure to leave the branch collar. Prune all epicormic branches in late summer.
- Water weekly during droughts. Water in the morning and avoid wetting the foliage.
- Fertilize to provide nutrient-rich soil. Have soil tested to be certain what quantities of nutrients are needed.
- Avoid mechanical and chemical injuries to the trees. Lawnmower and string-trimmer wounds are particularly troublesome.
- Apply fungicides registered for prevention or control of dogwood anthracnose when it is necessary to do so. Fungicides (Banner and Daconil 2787 are registered for control) should be applied as buds are breaking in the spring and at least twice thereafter as the leaves are expanding. Check with your local Extension Service about registration and use before applying any fungicide
http://fhpr8.srs.fs.fed.us/pubs/dogwood/r8-pr26/dwr8pr26.htm
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