Melody Perfumme, Hybrid Tea - Photo by Irene Roth
The plant family most bothered by the greatest number of disease problems is the rose family. This family not only consists of the roses we love and care for but also the related trees such as crab apples, flowering pears, cherries, peaches and plums, hawthorns, serviceberries and mountain ash. There have been many diseases catalogued and described in various books, though most rose gardeners will likely never be bothered with the majority of them. However, there are three rose diseases that seem to afflict the rose garden at one time or another:
Where you garden and weather conditions have much to do with how severely these fungal diseases will affect your roses. Areas where warm days and cool nights are the norm may offer ideal conditions for some fungal diseases to manifest. Also extended periods of moisture such as summer fogs, heavy dews and high humidity can create ideal conditions for the growth and spread of disease. The gardener can minimize these affects by spacing the roses well thus providing good air circulation. Also limiting excessive watering is very helpful, especially if this takes place in the morning and not in the evening, thus allowing the water on the foliage to dry off more quickly during the day.
There are many new varieties of roses that have been bred for disease resistance. It is worthwhile investing in these. From personal experience, it has been found that if the majority of the roses in the garden are disease resistant the entire garden will be minimally affected by disease. Of course there are the certain particular roses such as heirloom, old fashioned and those that one 'simply must have' due to their fragrance or color or name appeal, that may be disease susceptible. One solution is to isolate and grow this rose away from the others (if the rose garden is in the backyard, plant the rose with disease tendencies in the front yard, for example). This will help minimize the possibility of infecting the rest. Of course special attention needs to be given a rose with disease tendencies, above all keeping the foliage dry...a location with excellent air circulation helps. Try experimenting by moving roses about in the garden (during dormant period) in an effort to find the optimal growing settings.
Finally, if all efforts to prevent the fungal diseases fail and you spot the first telltale signs of trouble; and if you happen to prefer the chemical-free approach to rose gardening, here is a preventative spray you can try:
All Purpose Rose Disease Fighter
- 1 medium onion, chopped
- 3 - 4 cloves garlic, crushed
- ½ Jalapeno pepper, crushed
- 1½ tsp baking soda
- Cheesecloth or fine mesh
- Spray bottle
- 1 or 2 drops dishwashing liquid (or Insecticide soap) to help mixture adhere to foliage
- Steep garlic, onion and pepper in 1 quart of warm water for 1 hour.
- Strain the mix through the cheesecloth or mesh and retain liquid, add the baking soda
- In spray bottle dilute 1 part of the strained liquid with 4 parts warm water and add the dishwashing liquid.
- Mist plants lightly.
This formulation has the added benefit of repelling insects as well. Good luck and happy rose growing!