Mark’s Mayhems and Maladies
English/Cottage Gardens vs Traditional Gardens for Reducing Diseases
Traditional monoculture rose gardens (left photo) remain popular with rosarians that exhibit roses and also with beginner rosarians. English or cottage gardens with roses mixed with other types of plants (right photo) have become more popular in the U.S. in the last 15 years. Usually, cottage or English gardens, though producing many blooms, do not produce the size of blooms craved by exhibitors. Both types of gardens present advantages and disadvantages when it comes to minimizing the effects of diseases in the garden.
With traditional rose gardens it is much more difficult to control diseases like black spot, Cercospora leaf spot, powdery mildew, and rose rosette disease (RRD) since many of the plants in the garden (roses) are susceptible to these diseases and are crowded together. Diseases caused by pathogens whose reproductive propagules are spread in splashing rain, such as black spot fungus spores, are particularly harder to control in monoculture conditions. Eriophyid mites are spread more rapidly and populations increase much quicker in gardens with just roses. This makes management of RRD more difficult. In cottage gardens, roses are intermixed with other species of plants that are less likely to be susceptible to rose diseases. The companion plants are usually nonhosts for eriophyid mites which makes mite population build-up less likely.
One disadvantage of cottage gardens is that care has to be made when matching companion plants with roses so that the companion plants do not over grow or shade the roses. Shaded roses are usually more susceptible to fungal diseases. If planted too close together, companion plants may also out complete roses for water and nutrients. Stressed roses are more susceptible to disease. However, with proper planning and spacing of plants, cottage gardens can have great roses that usually require less maintenance for disease control. Diseases spread by vectors that have limited host ranges (i.e. Phyllocoptes fructiphilus - the eriophyid mite that spreads RRD) would have a much more difficult time spreading between roses since the companion plants are nonhosts and would serve as barriers to ballooning mites.
Mark Windham was a distinguished professor of ornamental pathology at the University of Tennessee, Knoxville. After retirement, Mark and his wife Karen love to walk beaches, visit with old rose friends, and enjoy grandchildren.