Research Gaps in the Study of Dogwood Anthracnose

There are still many gaps in our knowledge of this relatively new disease. Daughtrey and others (1996) highlighted the following research questions regarding dogwood anthracnose.

1. Where did anthracnose originate? Several lines of evidence, such as the lack of disease symptoms prior to 1970, the appearance of the disease near ports of entry (Seattle and New York), its rapid spread, and its lethal nature, suggest that dogwood anthracnose was introduced. However, the origin of the fungus remains unknown (Daughtreyand others1996).
2. What are its long-term effects on dogwood populations? Relatively little is known about the long-term effects of anthracnose on native dogwood populations. In woodland areas where mortality of dogwoods was severe over a decade ago, there is little regeneration by seedlings even though seed-bearing trees have survived (Daughtrey and Hibben 1994). Will such sites gradually become repopulated with C. florida, and how long will D. destructiva remain at a high enough level to initiate new infections (Daughtrey 1996) ?
3. What are the effects of this disease on wildlife and nutrient cycling? The decline of dogwood populations will likely effect wildlife populations and nutrient cycling in forest soil, but these impacts have not been measured. Dozens of bird species, bears, and deer use dogwood as a source of mast or browse (Nash 1999). How will the decline of dogwood affect these wildlife populations? Dogwood leaves are high in calcium. Decomposition of dogwood leaves not only makes this critical element available for other plants, but buffers soil acidity (Nash 1999). How will the removal of this source of calcium affect nutrient cycling?
4. Can we induce genetic improvements in dogwoods susceptible to anthracnose? Conventional breeding methods to produce interspecific hybrids have been successful, but results take a long time (Orton 1993). Selecting disease resistance in native populations of C. florida have also been attempted, but the results are inconclusive (Daughtrey and Hibben 1994, Santamorand others1989). Will it be possible to use new genetic engineering techniques for direct transfer of disease-resistance genes? This approach could produce quicker results without compromising the ornamental qualities of dogwoods (Daughtreyand others1996).
5. Will hypovirulent strains of the anthracnose pathogen slow the disease? Hypovirulent (weakened) strains of the chestnut blight pathogen cause a less severe reaction in their woody hosts than do the normal virulent strains. Research into possible hypovirulence in D. destructiva may uncover a biocontrol for this disease (Daughtrey and others 1996).